root/Source/core/rendering/RenderBox.cpp

DEFINITIONS

1. skipBodyBackground
2. m_maxPreferredLogicalWidth
3. willBeDestroyed
4. removeFloatingOrPositionedChildFromBlockLists
5. styleWillChange
6. styleDidChange
7. updateShapeOutsideInfoAfterStyleChange
8. updateGridPositionAfterStyleChange
9. updateFromStyle
10. layout
11. clientWidth
12. clientHeight
13. pixelSnappedClientWidth
14. pixelSnappedClientHeight
15. pixelSnappedOffsetWidth
16. pixelSnappedOffsetHeight
17. canDetermineWidthWithoutLayout
18. fixedOffsetWidth
19. scrollWidth
20. scrollHeight
21. scrollLeft
22. scrollTop
23. setScrollLeft
24. setScrollTop
25. scrollToOffset
26. frameElementAndViewPermitScroll
27. scrollRectToVisible
28. absoluteRects
29. absoluteQuads
30. updateLayerTransform
31. constrainLogicalWidthByMinMax
32. constrainLogicalHeightByMinMax
33. constrainContentBoxLogicalHeightByMinMax
34. absoluteContentBox
35. absoluteContentQuad
36. addFocusRingRects
37. canResize
38. addLayerHitTestRects
39. computeSelfHitTestRects
40. reflectionBox
41. reflectionOffset
42. reflectedRect
43. verticalScrollbarWidth
44. horizontalScrollbarHeight
45. instrinsicScrollbarLogicalWidth
46. scroll
47. canBeScrolledAndHasScrollableArea
48. canBeProgramaticallyScrolled
49. usesCompositedScrolling
50. autoscroll
51. autoscrollInProgress
52. canAutoscroll
53. calculateAutoscrollDirection
54. findAutoscrollable
55. adjustedScrollDelta
56. adjustedScrollDelta
57. panScroll
58. scrollByRecursively
59. needsPreferredWidthsRecalculation
60. scrolledContentOffset
61. cachedSizeForOverflowClip
62. applyCachedClipAndScrollOffsetForRepaint
63. computeIntrinsicLogicalWidths
64. minPreferredLogicalWidth
65. maxPreferredLogicalWidth
66. hasOverrideHeight
67. hasOverrideWidth
68. setOverrideLogicalContentHeight
69. setOverrideLogicalContentWidth
70. clearOverrideLogicalContentHeight
71. clearOverrideLogicalContentWidth
72. clearOverrideSize
73. overrideLogicalContentWidth
74. overrideLogicalContentHeight
75. overrideContainingBlockContentLogicalWidth
76. overrideContainingBlockContentLogicalHeight
77. hasOverrideContainingBlockLogicalWidth
78. hasOverrideContainingBlockLogicalHeight
79. setOverrideContainingBlockContentLogicalWidth
80. setOverrideContainingBlockContentLogicalHeight
81. clearContainingBlockOverrideSize
82. clearOverrideContainingBlockContentLogicalHeight
83. adjustBorderBoxLogicalWidthForBoxSizing
84. adjustBorderBoxLogicalHeightForBoxSizing
85. adjustContentBoxLogicalWidthForBoxSizing
86. adjustContentBoxLogicalHeightForBoxSizing
87. nodeAtPoint
88. paint
89. paintRootBoxFillLayers
90. determineBackgroundBleedAvoidance
91. paintBoxDecorations
92. paintBoxDecorationsWithRect
93. paintBackgroundWithBorderAndBoxShadow
94. paintBackground
95. getBackgroundPaintedExtent
96. backgroundIsKnownToBeOpaqueInRect
97. isCandidateForOpaquenessTest
98. foregroundIsKnownToBeOpaqueInRect
99. computeBackgroundIsKnownToBeObscured
100. backgroundHasOpaqueTopLayer
101. paintMask
102. paintClippingMask
103. paintMaskImages
104. maskClipRect
105. paintFillLayers
106. paintFillLayer
107. layersUseImage
108. imageChanged
109. repaintLayerRectsForImage
110. pushContentsClip
111. popContentsClip
112. overflowClipRect
113. clipRect
114. shrinkLogicalWidthToAvoidFloats
115. containingBlockLogicalWidthForContent
116. containingBlockLogicalHeightForContent
117. containingBlockAvailableLineWidth
118. perpendicularContainingBlockLogicalHeight
119. mapLocalToContainer
120. mapAbsoluteToLocalPoint
121. offsetFromContainer
122. createInlineBox
123. dirtyLineBoxes
124. positionLineBox
125. deleteLineBoxWrapper
126. clippedOverflowRectForRepaint
127. computeRectForRepaint
128. repaintDuringLayoutIfMoved
129. repaintOverhangingFloats
130. updateLogicalWidth
131. getMaxWidthListMarker
132. computeLogicalWidth
133. fillAvailableMeasure
134. fillAvailableMeasure
135. computeIntrinsicLogicalWidthUsing
136. computeLogicalWidthUsing
137. columnFlexItemHasStretchAlignment
138. isStretchingColumnFlexItem
139. sizesLogicalWidthToFitContent
140. autoWidthShouldFitContent
141. computeInlineDirectionMargins
142. shouldFlipBeforeAfterMargins
143. updateLogicalHeight
144. computeLogicalHeight
145. viewLogicalHeightForPercentages
146. computeLogicalHeightUsing
147. computeContentLogicalHeight
148. computeIntrinsicLogicalContentHeightUsing
149. computeContentAndScrollbarLogicalHeightUsing
150. skipContainingBlockForPercentHeightCalculation
151. computePercentageLogicalHeight
152. computeReplacedLogicalWidth
153. computeReplacedLogicalWidthRespectingMinMaxWidth
154. computeReplacedLogicalWidthUsing
155. computeReplacedLogicalHeight
156. computeReplacedLogicalHeightRespectingMinMaxHeight
157. computeReplacedLogicalHeightUsing
158. availableLogicalHeight
159. availableLogicalHeightUsing
160. computeBlockDirectionMargins
161. computeAndSetBlockDirectionMargins
162. containingBlockLogicalWidthForPositioned
163. containingBlockLogicalHeightForPositioned
164. computeInlineStaticDistance
165. computePositionedLogicalWidth
166. computeLogicalLeftPositionedOffset
167. shrinkToFitWidth
168. computePositionedLogicalWidthUsing
169. computeBlockStaticDistance
170. computePositionedLogicalHeight
171. computeLogicalTopPositionedOffset
172. computePositionedLogicalHeightUsing
173. computePositionedLogicalWidthReplaced
174. computePositionedLogicalHeightReplaced
175. localCaretRect
176. positionForPoint
177. shrinkToAvoidFloats
178. avoidsFloats
179. markForPaginationRelayoutIfNeeded
180. addVisualEffectOverflow
181. addOverflowFromChild
182. addLayoutOverflow
183. addVisualOverflow
184. addContentsVisualOverflow
185. clearLayoutOverflow
186. percentageLogicalHeightIsResolvable
187. percentageLogicalHeightIsResolvableFromBlock
188. hasUnsplittableScrollingOverflow
189. isUnsplittableForPagination
190. lineHeight
191. baselinePosition
192. enclosingFloatPaintingLayer
193. logicalVisualOverflowRectForPropagation
194. visualOverflowRectForPropagation
195. logicalLayoutOverflowRectForPropagation
196. layoutOverflowRectForPropagation
197. noOverflowRect
198. overflowRectForPaintRejection
199. offsetLeft
200. offsetTop
201. flipForWritingModeForChild
202. flipForWritingMode
203. flipForWritingMode
204. flipForWritingMode
205. flipForWritingModeIncludingColumns
206. flipForWritingMode
207. flipForWritingMode
208. flipForWritingMode
209. topLeftLocation
210. topLeftLocationOffset
211. hasRelativeLogicalHeight
212. markBoxForRelayoutAfterSplit
213. splitAnonymousBoxesAroundChild
214. offsetFromLogicalTopOfFirstPage

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
 *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
 * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
 * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "core/rendering/RenderBox.h"

#include <math.h>
#include <algorithm>
#include "HTMLNames.h"
#include "core/dom/Document.h"
#include "core/editing/htmlediting.h"
#include "core/frame/FrameView.h"
#include "core/frame/LocalFrame.h"
#include "core/html/HTMLElement.h"
#include "core/html/HTMLFrameElementBase.h"
#include "core/html/HTMLFrameOwnerElement.h"
#include "core/page/AutoscrollController.h"
#include "core/page/EventHandler.h"
#include "core/page/Page.h"
#include "core/rendering/HitTestResult.h"
#include "core/rendering/LayoutRectRecorder.h"
#include "core/rendering/PaintInfo.h"
#include "core/rendering/RenderDeprecatedFlexibleBox.h"
#include "core/rendering/RenderFlexibleBox.h"
#include "core/rendering/RenderGeometryMap.h"
#include "core/rendering/RenderGrid.h"
#include "core/rendering/RenderInline.h"
#include "core/rendering/RenderLayer.h"
#include "core/rendering/RenderListMarker.h"
#include "core/rendering/RenderTableCell.h"
#include "core/rendering/RenderTheme.h"
#include "core/rendering/RenderView.h"
#include "core/rendering/compositing/RenderLayerCompositor.h"
#include "platform/LengthFunctions.h"
#include "platform/geometry/FloatQuad.h"
#include "platform/geometry/TransformState.h"
#include "platform/graphics/GraphicsContextStateSaver.h"

using namespace std;

namespace WebCore {

using namespace HTMLNames;

// Used by flexible boxes when flexing this element and by table cells.
typedef WTF::HashMap<const RenderBox*, LayoutUnit> OverrideSizeMap;

// Used by grid elements to properly size their grid items.
// FIXME: Move these into RenderBoxRareData.
static OverrideSizeMap* gOverrideContainingBlockLogicalHeightMap = 0;
static OverrideSizeMap* gOverrideContainingBlockLogicalWidthMap = 0;


// Size of border belt for autoscroll. When mouse pointer in border belt,
// autoscroll is started.
static const int autoscrollBeltSize = 20;
static const unsigned backgroundObscurationTestMaxDepth = 4;

static bool skipBodyBackground(const RenderBox* bodyElementRenderer)
{
    ASSERT(bodyElementRenderer->isBody());
    // The <body> only paints its background if the root element has defined a background independent of the body,
    // or if the <body>'s parent is not the document element's renderer (e.g. inside SVG foreignObject).
    RenderObject* documentElementRenderer = bodyElementRenderer->document().documentElement()->renderer();
    return documentElementRenderer
        && !documentElementRenderer->hasBackground()
        && (documentElementRenderer == bodyElementRenderer->parent());
}

RenderBox::RenderBox(ContainerNode* node)
    : RenderBoxModelObject(node)
    , m_intrinsicContentLogicalHeight(-1)
    , m_minPreferredLogicalWidth(-1)
    , m_maxPreferredLogicalWidth(-1)
{
    setIsBox();
}

void RenderBox::willBeDestroyed()
{
    clearOverrideSize();
    clearContainingBlockOverrideSize();

    RenderBlock::removePercentHeightDescendantIfNeeded(this);

    ShapeOutsideInfo::removeInfo(*this);

    RenderBoxModelObject::willBeDestroyed();
}

void RenderBox::removeFloatingOrPositionedChildFromBlockLists()
{
    ASSERT(isFloatingOrOutOfFlowPositioned());

    if (documentBeingDestroyed())
        return;

    if (isFloating()) {
        RenderBlockFlow* parentBlockFlow = 0;
        for (RenderObject* curr = parent(); curr && !curr->isRenderView(); curr = curr->parent()) {
            if (curr->isRenderBlockFlow()) {
                RenderBlockFlow* currBlockFlow = toRenderBlockFlow(curr);
                if (!parentBlockFlow || currBlockFlow->containsFloat(this))
                    parentBlockFlow = currBlockFlow;
            }
        }

        if (parentBlockFlow) {
            parentBlockFlow->markSiblingsWithFloatsForLayout(this);
            parentBlockFlow->markAllDescendantsWithFloatsForLayout(this, false);
        }
    }

    if (isOutOfFlowPositioned())
        RenderBlock::removePositionedObject(this);
}

void RenderBox::styleWillChange(StyleDifference diff, const RenderStyle& newStyle)
{
    RenderStyle* oldStyle = style();
    if (oldStyle) {
        // The background of the root element or the body element could propagate up to
        // the canvas.  Just dirty the entire canvas when our style changes substantially.
        if (diff >= StyleDifferenceRepaint && node() &&
            (isHTMLHtmlElement(*node()) || isHTMLBodyElement(*node()))) {

            if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled() || diff != StyleDifferenceLayout)
                view()->repaint();

            if (oldStyle->hasEntirelyFixedBackground() != newStyle.hasEntirelyFixedBackground())
                view()->compositor()->rootFixedBackgroundsChanged();
        }

        // When a layout hint happens and an object's position style changes, we have to do a layout
        // to dirty the render tree using the old position value now.
        if (diff == StyleDifferenceLayout && parent() && oldStyle->position() != newStyle.position()) {
            markContainingBlocksForLayout();
            if (oldStyle->position() == StaticPosition)
                repaint();
            else if (newStyle.hasOutOfFlowPosition())
                parent()->setChildNeedsLayout();
            if (isFloating() && !isOutOfFlowPositioned() && newStyle.hasOutOfFlowPosition())
                removeFloatingOrPositionedChildFromBlockLists();
        }
    // FIXME: This branch runs when !oldStyle, which means that layout was never called
    // so what's the point in invalidating the whole view that we never painted?
    } else if (isBody())
        view()->repaint();

    RenderBoxModelObject::styleWillChange(diff, newStyle);
}

void RenderBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
{
    // Horizontal writing mode definition is updated in RenderBoxModelObject::updateFromStyle,
    // (as part of the RenderBoxModelObject::styleDidChange call below). So, we can safely cache the horizontal
    // writing mode value before style change here.
    bool oldHorizontalWritingMode = isHorizontalWritingMode();

    RenderBoxModelObject::styleDidChange(diff, oldStyle);

    RenderStyle* newStyle = style();
    if (needsLayout() && oldStyle) {
        RenderBlock::removePercentHeightDescendantIfNeeded(this);

        // Normally we can do optimized positioning layout for absolute/fixed positioned objects. There is one special case, however, which is
        // when the positioned object's margin-before is changed. In this case the parent has to get a layout in order to run margin collapsing
        // to determine the new static position.
        if (isOutOfFlowPositioned() && newStyle->hasStaticBlockPosition(isHorizontalWritingMode()) && oldStyle->marginBefore() != newStyle->marginBefore()
            && parent() && !parent()->normalChildNeedsLayout())
            parent()->setChildNeedsLayout();
    }

    if (RenderBlock::hasPercentHeightContainerMap() && firstChild()
        && oldHorizontalWritingMode != isHorizontalWritingMode())
        RenderBlock::clearPercentHeightDescendantsFrom(this);

    // If our zoom factor changes and we have a defined scrollLeft/Top, we need to adjust that value into the
    // new zoomed coordinate space.
    if (hasOverflowClip() && oldStyle && newStyle && oldStyle->effectiveZoom() != newStyle->effectiveZoom() && layer()) {
        if (int left = layer()->scrollableArea()->scrollXOffset()) {
            left = (left / oldStyle->effectiveZoom()) * newStyle->effectiveZoom();
            layer()->scrollableArea()->scrollToXOffset(left);
        }
        if (int top = layer()->scrollableArea()->scrollYOffset()) {
            top = (top / oldStyle->effectiveZoom()) * newStyle->effectiveZoom();
            layer()->scrollableArea()->scrollToYOffset(top);
        }
    }

    // Our opaqueness might have changed without triggering layout.
    if (diff == StyleDifferenceRepaint || diff == StyleDifferenceRepaintIfTextOrColorChange || diff == StyleDifferenceRepaintLayer) {
        RenderObject* parentToInvalidate = parent();
        for (unsigned i = 0; i < backgroundObscurationTestMaxDepth && parentToInvalidate; ++i) {
            parentToInvalidate->invalidateBackgroundObscurationStatus();
            parentToInvalidate = parentToInvalidate->parent();
        }
    }

    if (isRoot() || isBody())
        document().view()->recalculateScrollbarOverlayStyle();

    updateShapeOutsideInfoAfterStyleChange(*style(), oldStyle);
    updateGridPositionAfterStyleChange(oldStyle);
}

void RenderBox::updateShapeOutsideInfoAfterStyleChange(const RenderStyle& style, const RenderStyle* oldStyle)
{
    const ShapeValue* shapeOutside = style.shapeOutside();
    const ShapeValue* oldShapeOutside = oldStyle ? oldStyle->shapeOutside() : RenderStyle::initialShapeOutside();

    Length shapeMargin = style.shapeMargin();
    Length oldShapeMargin = oldStyle ? oldStyle->shapeMargin() : RenderStyle::initialShapeMargin();

    float shapeImageThreshold = style.shapeImageThreshold();
    float oldShapeImageThreshold = oldStyle ? oldStyle->shapeImageThreshold() : RenderStyle::initialShapeImageThreshold();

    // FIXME: A future optimization would do a deep comparison for equality. (bug 100811)
    if (shapeOutside == oldShapeOutside && shapeMargin == oldShapeMargin && shapeImageThreshold == oldShapeImageThreshold)
        return;

    if (!shapeOutside)
        ShapeOutsideInfo::removeInfo(*this);
    else
        ShapeOutsideInfo::ensureInfo(*this).markShapeAsDirty();

    if (shapeOutside || shapeOutside != oldShapeOutside)
        markShapeOutsideDependentsForLayout();
}

void RenderBox::updateGridPositionAfterStyleChange(const RenderStyle* oldStyle)
{
    if (!oldStyle || !parent() || !parent()->isRenderGrid())
        return;

    if (oldStyle->gridColumnStart() == style()->gridColumnStart()
        && oldStyle->gridColumnEnd() == style()->gridColumnEnd()
        && oldStyle->gridRowStart() == style()->gridRowStart()
        && oldStyle->gridRowEnd() == style()->gridRowEnd()
        && oldStyle->order() == style()->order()
        && oldStyle->hasOutOfFlowPosition() == style()->hasOutOfFlowPosition())
        return;

    // It should be possible to not dirty the grid in some cases (like moving an explicitly placed grid item).
    // For now, it's more simple to just always recompute the grid.
    toRenderGrid(parent())->dirtyGrid();
}

void RenderBox::updateFromStyle()
{
    RenderBoxModelObject::updateFromStyle();

    RenderStyle* styleToUse = style();
    bool isRootObject = isRoot();
    bool isViewObject = isRenderView();

    // The root and the RenderView always paint their backgrounds/borders.
    if (isRootObject || isViewObject)
        setHasBoxDecorations(true);

    setFloating(!isOutOfFlowPositioned() && styleToUse->isFloating());

    bool boxHasOverflowClip = false;
    if (!styleToUse->isOverflowVisible() && isRenderBlock() && !isViewObject) {
        // If overflow has been propagated to the viewport, it has no effect here.
        if (node() != document().viewportDefiningElement()) {
            boxHasOverflowClip = true;
            if (!hasOverflowClip()) {
                // If we are getting an overflow clip, preemptively erase any overflowing content.
                // FIXME: This should probably consult RenderOverflow.
                if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled())
                    repaint();
            }
        }
    }

    if (RuntimeEnabledFeatures::repaintAfterLayoutEnabled() && (boxHasOverflowClip != hasOverflowClip())) {
        // FIXME: This shouldn't be required if we tracked the visual overflow
        // generated by positioned children or self painting layers. crbug.com/345403
        for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
            LayoutRectRecorder childRecorder(*child);
            child->setShouldDoFullRepaintIfSelfPaintingLayer(true);
        }
    }

    setHasOverflowClip(boxHasOverflowClip);

    setHasTransform(styleToUse->hasTransformRelatedProperty());
    setHasReflection(styleToUse->boxReflect());
}

void RenderBox::layout()
{
    ASSERT(needsLayout());

    LayoutRectRecorder recorder(*this);

    RenderObject* child = firstChild();
    if (!child) {
        clearNeedsLayout();
        return;
    }

    LayoutStateMaintainer statePusher(*this, locationOffset());
    while (child) {
        child->layoutIfNeeded();
        ASSERT(!child->needsLayout());
        child = child->nextSibling();
    }
    invalidateBackgroundObscurationStatus();
    clearNeedsLayout();
}

// More IE extensions.  clientWidth and clientHeight represent the interior of an object
// excluding border and scrollbar.
LayoutUnit RenderBox::clientWidth() const
{
    return width() - borderLeft() - borderRight() - verticalScrollbarWidth();
}

LayoutUnit RenderBox::clientHeight() const
{
    return height() - borderTop() - borderBottom() - horizontalScrollbarHeight();
}

int RenderBox::pixelSnappedClientWidth() const
{
    return snapSizeToPixel(clientWidth(), x() + clientLeft());
}

int RenderBox::pixelSnappedClientHeight() const
{
    return snapSizeToPixel(clientHeight(), y() + clientTop());
}

int RenderBox::pixelSnappedOffsetWidth() const
{
    return snapSizeToPixel(offsetWidth(), x() + clientLeft());
}

int RenderBox::pixelSnappedOffsetHeight() const
{
    return snapSizeToPixel(offsetHeight(), y() + clientTop());
}

bool RenderBox::canDetermineWidthWithoutLayout() const
{
    // FIXME: Remove function and callers.
    return false;
}

LayoutUnit RenderBox::fixedOffsetWidth() const
{
    ASSERT(canDetermineWidthWithoutLayout());

    RenderStyle* style = this->style();

    LayoutUnit width = std::max(LayoutUnit(style->minWidth().value()), LayoutUnit(style->width().value()));
    if (style->maxWidth().isFixed())
        width = std::min(LayoutUnit(style->maxWidth().value()), width);

    LayoutUnit borderLeft = style->borderLeft().nonZero() ? style->borderLeft().width() : 0;
    LayoutUnit borderRight = style->borderRight().nonZero() ? style->borderRight().width() : 0;

    return width + borderLeft + borderRight + style->paddingLeft().value() + style->paddingRight().value();
}

int RenderBox::scrollWidth() const
{
    if (hasOverflowClip())
        return layer()->scrollableArea()->scrollWidth();
    // For objects with visible overflow, this matches IE.
    // FIXME: Need to work right with writing modes.
    if (style()->isLeftToRightDirection())
        return snapSizeToPixel(max(clientWidth(), layoutOverflowRect().maxX() - borderLeft()), x() + clientLeft());
    return clientWidth() - min<LayoutUnit>(0, layoutOverflowRect().x() - borderLeft());
}

int RenderBox::scrollHeight() const
{
    if (hasOverflowClip())
        return layer()->scrollableArea()->scrollHeight();
    // For objects with visible overflow, this matches IE.
    // FIXME: Need to work right with writing modes.
    return snapSizeToPixel(max(clientHeight(), layoutOverflowRect().maxY() - borderTop()), y() + clientTop());
}

int RenderBox::scrollLeft() const
{
    return hasOverflowClip() ? layer()->scrollableArea()->scrollXOffset() : 0;
}

int RenderBox::scrollTop() const
{
    return hasOverflowClip() ? layer()->scrollableArea()->scrollYOffset() : 0;
}

void RenderBox::setScrollLeft(int newLeft)
{
    // This doesn't hit in any tests, but since the equivalent code in setScrollTop
    // does, presumably this code does as well.
    DisableCompositingQueryAsserts disabler;

    if (hasOverflowClip())
        layer()->scrollableArea()->scrollToXOffset(newLeft, ScrollOffsetClamped);
}

void RenderBox::setScrollTop(int newTop)
{
    // Hits in compositing/overflow/do-not-assert-on-invisible-composited-layers.html
    DisableCompositingQueryAsserts disabler;

    if (hasOverflowClip())
        layer()->scrollableArea()->scrollToYOffset(newTop, ScrollOffsetClamped);
}

void RenderBox::scrollToOffset(const IntSize& offset)
{
    ASSERT(hasOverflowClip());

    // This doesn't hit in any tests, but since the equivalent code in setScrollTop
    // does, presumably this code does as well.
    DisableCompositingQueryAsserts disabler;
    layer()->scrollableArea()->scrollToOffset(offset, ScrollOffsetClamped);
}

static inline bool frameElementAndViewPermitScroll(HTMLFrameElementBase* frameElementBase, FrameView* frameView)
{
    // If scrollbars aren't explicitly forbidden, permit scrolling.
    if (frameElementBase && frameElementBase->scrollingMode() != ScrollbarAlwaysOff)
        return true;

    // If scrollbars are forbidden, user initiated scrolls should obviously be ignored.
    if (frameView->wasScrolledByUser())
        return false;

    // Forbid autoscrolls when scrollbars are off, but permits other programmatic scrolls,
    // like navigation to an anchor.
    Page* page = frameView->frame().page();
    if (!page)
        return false;
    return !page->autoscrollController().autoscrollInProgress();
}

void RenderBox::scrollRectToVisible(const LayoutRect& rect, const ScrollAlignment& alignX, const ScrollAlignment& alignY)
{
    // Presumably the same issue as in setScrollTop. See crbug.com/343132.
    DisableCompositingQueryAsserts disabler;

    RenderBox* parentBox = 0;
    LayoutRect newRect = rect;

    bool restrictedByLineClamp = false;
    if (parent()) {
        parentBox = parent()->enclosingBox();
        restrictedByLineClamp = !parent()->style()->lineClamp().isNone();
    }

    if (hasOverflowClip() && !restrictedByLineClamp) {
        // Don't scroll to reveal an overflow layer that is restricted by the -webkit-line-clamp property.
        // This will prevent us from revealing text hidden by the slider in Safari RSS.
        newRect = layer()->scrollableArea()->exposeRect(rect, alignX, alignY);
    } else if (!parentBox && canBeProgramaticallyScrolled()) {
        if (FrameView* frameView = this->frameView()) {
            Element* ownerElement = document().ownerElement();

            if (ownerElement && ownerElement->renderer()) {
                HTMLFrameElementBase* frameElementBase = 0;

                if (isHTMLFrameElement(*ownerElement) || isHTMLIFrameElement(*ownerElement))
                    frameElementBase = toHTMLFrameElementBase(ownerElement);

                if (frameElementAndViewPermitScroll(frameElementBase, frameView)) {
                    LayoutRect viewRect = frameView->visibleContentRect();
                    LayoutRect exposeRect = ScrollAlignment::getRectToExpose(viewRect, rect, alignX, alignY);

                    int xOffset = roundToInt(exposeRect.x());
                    int yOffset = roundToInt(exposeRect.y());
                    // Adjust offsets if they're outside of the allowable range.
                    xOffset = max(0, min(frameView->contentsWidth(), xOffset));
                    yOffset = max(0, min(frameView->contentsHeight(), yOffset));

                    frameView->setScrollPosition(IntPoint(xOffset, yOffset));
                    if (frameView->safeToPropagateScrollToParent()) {
                        parentBox = ownerElement->renderer()->enclosingBox();
                        // FIXME: This doesn't correctly convert the rect to
                        // absolute coordinates in the parent.
                        newRect.setX(rect.x() - frameView->scrollX() + frameView->x());
                        newRect.setY(rect.y() - frameView->scrollY() + frameView->y());
                    } else {
                        parentBox = 0;
                    }
                }
            } else {
                LayoutRect viewRect = frameView->visibleContentRect();
                LayoutRect r = ScrollAlignment::getRectToExpose(viewRect, rect, alignX, alignY);
                frameView->setScrollPosition(roundedIntPoint(r.location()));
            }
        }
    }

    if (frame()->page()->autoscrollController().autoscrollInProgress())
        parentBox = enclosingScrollableBox();

    if (parentBox)
        parentBox->scrollRectToVisible(newRect, alignX, alignY);
}

void RenderBox::absoluteRects(Vector<IntRect>& rects, const LayoutPoint& accumulatedOffset) const
{
    rects.append(pixelSnappedIntRect(accumulatedOffset, size()));
}

void RenderBox::absoluteQuads(Vector<FloatQuad>& quads, bool* wasFixed) const
{
    quads.append(localToAbsoluteQuad(FloatRect(0, 0, width().toFloat(), height().toFloat()), 0 /* mode */, wasFixed));
}

void RenderBox::updateLayerTransform()
{
    // Transform-origin depends on box size, so we need to update the layer transform after layout.
    if (hasLayer())
        layer()->updateTransform();
}

LayoutUnit RenderBox::constrainLogicalWidthByMinMax(LayoutUnit logicalWidth, LayoutUnit availableWidth, RenderBlock* cb) const
{
    RenderStyle* styleToUse = style();
    if (!styleToUse->logicalMaxWidth().isUndefined())
        logicalWidth = min(logicalWidth, computeLogicalWidthUsing(MaxSize, styleToUse->logicalMaxWidth(), availableWidth, cb));
    return max(logicalWidth, computeLogicalWidthUsing(MinSize, styleToUse->logicalMinWidth(), availableWidth, cb));
}

LayoutUnit RenderBox::constrainLogicalHeightByMinMax(LayoutUnit logicalHeight, LayoutUnit intrinsicContentHeight) const
{
    RenderStyle* styleToUse = style();
    if (!styleToUse->logicalMaxHeight().isUndefined()) {
        LayoutUnit maxH = computeLogicalHeightUsing(styleToUse->logicalMaxHeight(), intrinsicContentHeight);
        if (maxH != -1)
            logicalHeight = min(logicalHeight, maxH);
    }
    return max(logicalHeight, computeLogicalHeightUsing(styleToUse->logicalMinHeight(), intrinsicContentHeight));
}

LayoutUnit RenderBox::constrainContentBoxLogicalHeightByMinMax(LayoutUnit logicalHeight, LayoutUnit intrinsicContentHeight) const
{
    RenderStyle* styleToUse = style();
    if (!styleToUse->logicalMaxHeight().isUndefined()) {
        LayoutUnit maxH = computeContentLogicalHeight(styleToUse->logicalMaxHeight(), intrinsicContentHeight);
        if (maxH != -1)
            logicalHeight = min(logicalHeight, maxH);
    }
    return max(logicalHeight, computeContentLogicalHeight(styleToUse->logicalMinHeight(), intrinsicContentHeight));
}

IntRect RenderBox::absoluteContentBox() const
{
    // This is wrong with transforms and flipped writing modes.
    IntRect rect = pixelSnappedIntRect(contentBoxRect());
    FloatPoint absPos = localToAbsolute();
    rect.move(absPos.x(), absPos.y());
    return rect;
}

FloatQuad RenderBox::absoluteContentQuad() const
{
    LayoutRect rect = contentBoxRect();
    return localToAbsoluteQuad(FloatRect(rect));
}

void RenderBox::addFocusRingRects(Vector<IntRect>& rects, const LayoutPoint& additionalOffset, const RenderLayerModelObject*)
{
    if (!size().isEmpty())
        rects.append(pixelSnappedIntRect(additionalOffset, size()));
}

bool RenderBox::canResize() const
{
    // We need a special case for <iframe> because they never have
    // hasOverflowClip(). However, they do "implicitly" clip their contents, so
    // we want to allow resizing them also.
    return (hasOverflowClip() || isRenderIFrame()) && style()->resize() != RESIZE_NONE;
}

void RenderBox::addLayerHitTestRects(LayerHitTestRects& layerRects, const RenderLayer* currentLayer, const LayoutPoint& layerOffset, const LayoutRect& containerRect) const
{
    LayoutPoint adjustedLayerOffset = layerOffset + locationOffset();
    RenderBoxModelObject::addLayerHitTestRects(layerRects, currentLayer, adjustedLayerOffset, containerRect);
}

void RenderBox::computeSelfHitTestRects(Vector<LayoutRect>& rects, const LayoutPoint& layerOffset) const
{
    if (!size().isEmpty())
        rects.append(LayoutRect(layerOffset, size()));
}

LayoutRect RenderBox::reflectionBox() const
{
    LayoutRect result;
    if (!style()->boxReflect())
        return result;
    LayoutRect box = borderBoxRect();
    result = box;
    switch (style()->boxReflect()->direction()) {
        case ReflectionBelow:
            result.move(0, box.height() + reflectionOffset());
            break;
        case ReflectionAbove:
            result.move(0, -box.height() - reflectionOffset());
            break;
        case ReflectionLeft:
            result.move(-box.width() - reflectionOffset(), 0);
            break;
        case ReflectionRight:
            result.move(box.width() + reflectionOffset(), 0);
            break;
    }
    return result;
}

int RenderBox::reflectionOffset() const
{
    if (!style()->boxReflect())
        return 0;
    if (style()->boxReflect()->direction() == ReflectionLeft || style()->boxReflect()->direction() == ReflectionRight)
        return valueForLength(style()->boxReflect()->offset(), borderBoxRect().width());
    return valueForLength(style()->boxReflect()->offset(), borderBoxRect().height());
}

LayoutRect RenderBox::reflectedRect(const LayoutRect& r) const
{
    if (!style()->boxReflect())
        return LayoutRect();

    LayoutRect box = borderBoxRect();
    LayoutRect result = r;
    switch (style()->boxReflect()->direction()) {
        case ReflectionBelow:
            result.setY(box.maxY() + reflectionOffset() + (box.maxY() - r.maxY()));
            break;
        case ReflectionAbove:
            result.setY(box.y() - reflectionOffset() - box.height() + (box.maxY() - r.maxY()));
            break;
        case ReflectionLeft:
            result.setX(box.x() - reflectionOffset() - box.width() + (box.maxX() - r.maxX()));
            break;
        case ReflectionRight:
            result.setX(box.maxX() + reflectionOffset() + (box.maxX() - r.maxX()));
            break;
    }
    return result;
}

int RenderBox::verticalScrollbarWidth() const
{
    if (!hasOverflowClip() || style()->overflowY() == OOVERLAY)
        return 0;

    return layer()->scrollableArea()->verticalScrollbarWidth();
}

int RenderBox::horizontalScrollbarHeight() const
{
    if (!hasOverflowClip() || style()->overflowX() == OOVERLAY)
        return 0;

    return layer()->scrollableArea()->horizontalScrollbarHeight();
}

int RenderBox::instrinsicScrollbarLogicalWidth() const
{
    if (!hasOverflowClip())
        return 0;

    if (isHorizontalWritingMode() && style()->overflowY() == OSCROLL) {
        ASSERT(layer()->scrollableArea() && layer()->scrollableArea()->hasVerticalScrollbar());
        return verticalScrollbarWidth();
    }

    if (!isHorizontalWritingMode() && style()->overflowX() == OSCROLL) {
        ASSERT(layer()->scrollableArea() && layer()->scrollableArea()->hasHorizontalScrollbar());
        return horizontalScrollbarHeight();
    }

    return 0;
}

bool RenderBox::scroll(ScrollDirection direction, ScrollGranularity granularity, float delta)
{
    // Presumably the same issue as in setScrollTop. See crbug.com/343132.
    DisableCompositingQueryAsserts disabler;

    // Logical scroll is a higher level concept, all directions by here must be physical
    ASSERT(!isLogical(direction));

    if (!layer() || !layer()->scrollableArea())
        return false;

    return layer()->scrollableArea()->scroll(direction, granularity, delta);
}

bool RenderBox::canBeScrolledAndHasScrollableArea() const
{
    return canBeProgramaticallyScrolled() && (scrollHeight() != clientHeight() || scrollWidth() != clientWidth());
}

bool RenderBox::canBeProgramaticallyScrolled() const
{
    Node* node = this->node();
    if (node && node->isDocumentNode())
        return true;

    if (!hasOverflowClip())
        return false;

    bool hasScrollableOverflow = hasScrollableOverflowX() || hasScrollableOverflowY();
    if (scrollsOverflow() && hasScrollableOverflow)
        return true;

    return node && node->rendererIsEditable();
}

bool RenderBox::usesCompositedScrolling() const
{
    return hasOverflowClip() && hasLayer() && layer()->scrollableArea()->usesCompositedScrolling();
}

void RenderBox::autoscroll(const IntPoint& position)
{
    LocalFrame* frame = this->frame();
    if (!frame)
        return;

    FrameView* frameView = frame->view();
    if (!frameView)
        return;

    IntPoint currentDocumentPosition = frameView->windowToContents(position);
    scrollRectToVisible(LayoutRect(currentDocumentPosition, LayoutSize(1, 1)), ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignToEdgeIfNeeded);
}

bool RenderBox::autoscrollInProgress() const
{
    return frame() && frame()->page() && frame()->page()->autoscrollController().autoscrollInProgress(this);
}

// There are two kinds of renderer that can autoscroll.
bool RenderBox::canAutoscroll() const
{
    if (node() && node()->isDocumentNode())
        return view()->frameView()->isScrollable();

    // Check for a box that can be scrolled in its own right.
    return canBeScrolledAndHasScrollableArea();
}

// If specified point is in border belt, returned offset denotes direction of
// scrolling.
IntSize RenderBox::calculateAutoscrollDirection(const IntPoint& windowPoint) const
{
    if (!frame())
        return IntSize();

    FrameView* frameView = frame()->view();
    if (!frameView)
        return IntSize();

    IntRect box(absoluteBoundingBoxRect());
    box.move(view()->frameView()->scrollOffset());
    IntRect windowBox = view()->frameView()->contentsToWindow(box);

    IntPoint windowAutoscrollPoint = windowPoint;

    if (windowAutoscrollPoint.x() < windowBox.x() + autoscrollBeltSize)
        windowAutoscrollPoint.move(-autoscrollBeltSize, 0);
    else if (windowAutoscrollPoint.x() > windowBox.maxX() - autoscrollBeltSize)
        windowAutoscrollPoint.move(autoscrollBeltSize, 0);

    if (windowAutoscrollPoint.y() < windowBox.y() + autoscrollBeltSize)
        windowAutoscrollPoint.move(0, -autoscrollBeltSize);
    else if (windowAutoscrollPoint.y() > windowBox.maxY() - autoscrollBeltSize)
        windowAutoscrollPoint.move(0, autoscrollBeltSize);

    return windowAutoscrollPoint - windowPoint;
}

RenderBox* RenderBox::findAutoscrollable(RenderObject* renderer)
{
    while (renderer && !(renderer->isBox() && toRenderBox(renderer)->canAutoscroll())) {
        if (!renderer->parent() && renderer->node() == renderer->document() && renderer->document().ownerElement())
            renderer = renderer->document().ownerElement()->renderer();
        else
            renderer = renderer->parent();
    }

    return renderer && renderer->isBox() ? toRenderBox(renderer) : 0;
}

static inline int adjustedScrollDelta(int beginningDelta)
{
    // This implemention matches Firefox's.
    // http://mxr.mozilla.org/firefox/source/toolkit/content/widgets/browser.xml#856.
    const int speedReducer = 12;

    int adjustedDelta = beginningDelta / speedReducer;
    if (adjustedDelta > 1)
        adjustedDelta = static_cast<int>(adjustedDelta * sqrt(static_cast<double>(adjustedDelta))) - 1;
    else if (adjustedDelta < -1)
        adjustedDelta = static_cast<int>(adjustedDelta * sqrt(static_cast<double>(-adjustedDelta))) + 1;

    return adjustedDelta;
}

static inline IntSize adjustedScrollDelta(const IntSize& delta)
{
    return IntSize(adjustedScrollDelta(delta.width()), adjustedScrollDelta(delta.height()));
}

void RenderBox::panScroll(const IntPoint& sourcePoint)
{
    LocalFrame* frame = this->frame();
    if (!frame)
        return;

    IntPoint lastKnownMousePosition = frame->eventHandler().lastKnownMousePosition();

    // We need to check if the last known mouse position is out of the window. When the mouse is out of the window, the position is incoherent
    static IntPoint previousMousePosition;
    if (lastKnownMousePosition.x() < 0 || lastKnownMousePosition.y() < 0)
        lastKnownMousePosition = previousMousePosition;
    else
        previousMousePosition = lastKnownMousePosition;

    IntSize delta = lastKnownMousePosition - sourcePoint;

    if (abs(delta.width()) <= ScrollView::noPanScrollRadius) // at the center we let the space for the icon
        delta.setWidth(0);
    if (abs(delta.height()) <= ScrollView::noPanScrollRadius)
        delta.setHeight(0);

    scrollByRecursively(adjustedScrollDelta(delta), ScrollOffsetClamped);
}

void RenderBox::scrollByRecursively(const IntSize& delta, ScrollOffsetClamping clamp)
{
    if (delta.isZero())
        return;

    bool restrictedByLineClamp = false;
    if (parent())
        restrictedByLineClamp = !parent()->style()->lineClamp().isNone();

    if (hasOverflowClip() && !restrictedByLineClamp) {
        IntSize newScrollOffset = layer()->scrollableArea()->adjustedScrollOffset() + delta;
        layer()->scrollableArea()->scrollToOffset(newScrollOffset, clamp);

        // If this layer can't do the scroll we ask the next layer up that can scroll to try
        IntSize remainingScrollOffset = newScrollOffset - layer()->scrollableArea()->adjustedScrollOffset();
        if (!remainingScrollOffset.isZero() && parent()) {
            if (RenderBox* scrollableBox = enclosingScrollableBox())
                scrollableBox->scrollByRecursively(remainingScrollOffset, clamp);

            LocalFrame* frame = this->frame();
            if (frame && frame->page())
                frame->page()->autoscrollController().updateAutoscrollRenderer();
        }
    } else if (view()->frameView()) {
        // If we are here, we were called on a renderer that can be programmatically scrolled, but doesn't
        // have an overflow clip. Which means that it is a document node that can be scrolled.
        view()->frameView()->scrollBy(delta);

        // FIXME: If we didn't scroll the whole way, do we want to try looking at the frames ownerElement?
        // https://bugs.webkit.org/show_bug.cgi?id=28237
    }
}

bool RenderBox::needsPreferredWidthsRecalculation() const
{
    return style()->paddingStart().isPercent() || style()->paddingEnd().isPercent();
}

IntSize RenderBox::scrolledContentOffset() const
{
    ASSERT(hasOverflowClip());
    ASSERT(hasLayer());
    return layer()->scrollableArea()->scrollOffset();
}

LayoutSize RenderBox::cachedSizeForOverflowClip() const
{
    ASSERT(hasOverflowClip());
    ASSERT(hasLayer());
    return layer()->size();
}

void RenderBox::applyCachedClipAndScrollOffsetForRepaint(LayoutRect& paintRect) const
{
    flipForWritingMode(paintRect);
    paintRect.move(-scrolledContentOffset()); // For overflow:auto/scroll/hidden.

    // Do not clip scroll layer contents to reduce the number of repaints while scrolling.
    if (usesCompositedScrolling()) {
        flipForWritingMode(paintRect);
        return;
    }

    // height() is inaccurate if we're in the middle of a layout of this RenderBox, so use the
    // layer's size instead. Even if the layer's size is wrong, the layer itself will repaint
    // anyway if its size does change.
    LayoutRect clipRect(LayoutPoint(), cachedSizeForOverflowClip());
    paintRect = intersection(paintRect, clipRect);
    flipForWritingMode(paintRect);
}

void RenderBox::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
{
    minLogicalWidth = minPreferredLogicalWidth() - borderAndPaddingLogicalWidth();
    maxLogicalWidth = maxPreferredLogicalWidth() - borderAndPaddingLogicalWidth();
}

LayoutUnit RenderBox::minPreferredLogicalWidth() const
{
    if (preferredLogicalWidthsDirty()) {
#ifndef NDEBUG
        SetLayoutNeededForbiddenScope layoutForbiddenScope(const_cast<RenderBox*>(this));
#endif
        const_cast<RenderBox*>(this)->computePreferredLogicalWidths();
    }

    return m_minPreferredLogicalWidth;
}

LayoutUnit RenderBox::maxPreferredLogicalWidth() const
{
    if (preferredLogicalWidthsDirty()) {
#ifndef NDEBUG
        SetLayoutNeededForbiddenScope layoutForbiddenScope(const_cast<RenderBox*>(this));
#endif
        const_cast<RenderBox*>(this)->computePreferredLogicalWidths();
    }

    return m_maxPreferredLogicalWidth;
}

bool RenderBox::hasOverrideHeight() const
{
    return m_rareData && m_rareData->m_overrideLogicalContentHeight != -1;
}

bool RenderBox::hasOverrideWidth() const
{
    return m_rareData && m_rareData->m_overrideLogicalContentWidth != -1;
}

void RenderBox::setOverrideLogicalContentHeight(LayoutUnit height)
{
    ASSERT(height >= 0);
    ensureRareData().m_overrideLogicalContentHeight = height;
}

void RenderBox::setOverrideLogicalContentWidth(LayoutUnit width)
{
    ASSERT(width >= 0);
    ensureRareData().m_overrideLogicalContentWidth = width;
}

void RenderBox::clearOverrideLogicalContentHeight()
{
    if (m_rareData)
        m_rareData->m_overrideLogicalContentHeight = -1;
}

void RenderBox::clearOverrideLogicalContentWidth()
{
    if (m_rareData)
        m_rareData->m_overrideLogicalContentWidth = -1;
}

void RenderBox::clearOverrideSize()
{
    clearOverrideLogicalContentHeight();
    clearOverrideLogicalContentWidth();
}

LayoutUnit RenderBox::overrideLogicalContentWidth() const
{
    ASSERT(hasOverrideWidth());
    return m_rareData->m_overrideLogicalContentWidth;
}

LayoutUnit RenderBox::overrideLogicalContentHeight() const
{
    ASSERT(hasOverrideHeight());
    return m_rareData->m_overrideLogicalContentHeight;
}

LayoutUnit RenderBox::overrideContainingBlockContentLogicalWidth() const
{
    ASSERT(hasOverrideContainingBlockLogicalWidth());
    return gOverrideContainingBlockLogicalWidthMap->get(this);
}

LayoutUnit RenderBox::overrideContainingBlockContentLogicalHeight() const
{
    ASSERT(hasOverrideContainingBlockLogicalHeight());
    return gOverrideContainingBlockLogicalHeightMap->get(this);
}

bool RenderBox::hasOverrideContainingBlockLogicalWidth() const
{
    return gOverrideContainingBlockLogicalWidthMap && gOverrideContainingBlockLogicalWidthMap->contains(this);
}

bool RenderBox::hasOverrideContainingBlockLogicalHeight() const
{
    return gOverrideContainingBlockLogicalHeightMap && gOverrideContainingBlockLogicalHeightMap->contains(this);
}

void RenderBox::setOverrideContainingBlockContentLogicalWidth(LayoutUnit logicalWidth)
{
    if (!gOverrideContainingBlockLogicalWidthMap)
        gOverrideContainingBlockLogicalWidthMap = new OverrideSizeMap;
    gOverrideContainingBlockLogicalWidthMap->set(this, logicalWidth);
}

void RenderBox::setOverrideContainingBlockContentLogicalHeight(LayoutUnit logicalHeight)
{
    if (!gOverrideContainingBlockLogicalHeightMap)
        gOverrideContainingBlockLogicalHeightMap = new OverrideSizeMap;
    gOverrideContainingBlockLogicalHeightMap->set(this, logicalHeight);
}

void RenderBox::clearContainingBlockOverrideSize()
{
    if (gOverrideContainingBlockLogicalWidthMap)
        gOverrideContainingBlockLogicalWidthMap->remove(this);
    clearOverrideContainingBlockContentLogicalHeight();
}

void RenderBox::clearOverrideContainingBlockContentLogicalHeight()
{
    if (gOverrideContainingBlockLogicalHeightMap)
        gOverrideContainingBlockLogicalHeightMap->remove(this);
}

LayoutUnit RenderBox::adjustBorderBoxLogicalWidthForBoxSizing(LayoutUnit width) const
{
    LayoutUnit bordersPlusPadding = borderAndPaddingLogicalWidth();
    if (style()->boxSizing() == CONTENT_BOX)
        return width + bordersPlusPadding;
    return max(width, bordersPlusPadding);
}

LayoutUnit RenderBox::adjustBorderBoxLogicalHeightForBoxSizing(LayoutUnit height) const
{
    LayoutUnit bordersPlusPadding = borderAndPaddingLogicalHeight();
    if (style()->boxSizing() == CONTENT_BOX)
        return height + bordersPlusPadding;
    return max(height, bordersPlusPadding);
}

LayoutUnit RenderBox::adjustContentBoxLogicalWidthForBoxSizing(LayoutUnit width) const
{
    if (style()->boxSizing() == BORDER_BOX)
        width -= borderAndPaddingLogicalWidth();
    return max<LayoutUnit>(0, width);
}

LayoutUnit RenderBox::adjustContentBoxLogicalHeightForBoxSizing(LayoutUnit height) const
{
    if (style()->boxSizing() == BORDER_BOX)
        height -= borderAndPaddingLogicalHeight();
    return max<LayoutUnit>(0, height);
}

// Hit Testing
bool RenderBox::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction action)
{
    LayoutPoint adjustedLocation = accumulatedOffset + location();

    // Check kids first.
    for (RenderObject* child = lastChild(); child; child = child->previousSibling()) {
        if (!child->hasLayer() && child->nodeAtPoint(request, result, locationInContainer, adjustedLocation, action)) {
            updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
            return true;
        }
    }

    // Check our bounds next. For this purpose always assume that we can only be hit in the
    // foreground phase (which is true for replaced elements like images).
    LayoutRect boundsRect = borderBoxRect();
    boundsRect.moveBy(adjustedLocation);
    if (visibleToHitTestRequest(request) && action == HitTestForeground && locationInContainer.intersects(boundsRect)) {
        updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
        if (!result.addNodeToRectBasedTestResult(node(), request, locationInContainer, boundsRect))
            return true;
    }

    return false;
}

// --------------------- painting stuff -------------------------------

void RenderBox::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    LayoutPoint adjustedPaintOffset = paintOffset + location();
    // default implementation. Just pass paint through to the children
    PaintInfo childInfo(paintInfo);
    childInfo.updatePaintingRootForChildren(this);
    for (RenderObject* child = firstChild(); child; child = child->nextSibling())
        child->paint(childInfo, adjustedPaintOffset);
}

void RenderBox::paintRootBoxFillLayers(const PaintInfo& paintInfo)
{
    if (paintInfo.skipRootBackground())
        return;

    RenderObject* rootBackgroundRenderer = rendererForRootBackground();

    const FillLayer* bgLayer = rootBackgroundRenderer->style()->backgroundLayers();
    Color bgColor = rootBackgroundRenderer->resolveColor(CSSPropertyBackgroundColor);

    paintFillLayers(paintInfo, bgColor, bgLayer, view()->backgroundRect(this), BackgroundBleedNone, CompositeSourceOver, rootBackgroundRenderer);
}

BackgroundBleedAvoidance RenderBox::determineBackgroundBleedAvoidance(GraphicsContext* context) const
{
    if (context->paintingDisabled())
        return BackgroundBleedNone;

    const RenderStyle* style = this->style();

    if (!style->hasBackground() || !style->hasBorder() || !style->hasBorderRadius() || borderImageIsLoadedAndCanBeRendered())
        return BackgroundBleedNone;

    AffineTransform ctm = context->getCTM();
    FloatSize contextScaling(static_cast<float>(ctm.xScale()), static_cast<float>(ctm.yScale()));

    // Because RoundedRect uses IntRect internally the inset applied by the
    // BackgroundBleedShrinkBackground strategy cannot be less than one integer
    // layout coordinate, even with subpixel layout enabled. To take that into
    // account, we clamp the contextScaling to 1.0 for the following test so
    // that borderObscuresBackgroundEdge can only return true if the border
    // widths are greater than 2 in both layout coordinates and screen
    // coordinates.
    // This precaution will become obsolete if RoundedRect is ever promoted to
    // a sub-pixel representation.
    if (contextScaling.width() > 1)
        contextScaling.setWidth(1);
    if (contextScaling.height() > 1)
        contextScaling.setHeight(1);

    if (borderObscuresBackgroundEdge(contextScaling))
        return BackgroundBleedShrinkBackground;
    if (!style->hasAppearance() && borderObscuresBackground() && backgroundHasOpaqueTopLayer())
        return BackgroundBleedBackgroundOverBorder;

    return BackgroundBleedClipBackground;
}

void RenderBox::paintBoxDecorations(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    if (!paintInfo.shouldPaintWithinRoot(this))
        return;

    LayoutRect paintRect = borderBoxRect();
    paintRect.moveBy(paintOffset);
    paintBoxDecorationsWithRect(paintInfo, paintOffset, paintRect);
}

void RenderBox::paintBoxDecorationsWithRect(PaintInfo& paintInfo, const LayoutPoint& paintOffset, const LayoutRect& paintRect)
{
    BackgroundBleedAvoidance bleedAvoidance = determineBackgroundBleedAvoidance(paintInfo.context);

    // FIXME: Should eventually give the theme control over whether the box shadow should paint, since controls could have
    // custom shadows of their own.
    if (!boxShadowShouldBeAppliedToBackground(bleedAvoidance))
        paintBoxShadow(paintInfo, paintRect, style(), Normal);

    GraphicsContextStateSaver stateSaver(*paintInfo.context, false);
    if (bleedAvoidance == BackgroundBleedClipBackground) {
        stateSaver.save();
        RoundedRect border = style()->getRoundedBorderFor(paintRect);
        paintInfo.context->clipRoundedRect(border);
    }

    paintBackgroundWithBorderAndBoxShadow(paintInfo, paintRect, bleedAvoidance);
}

void RenderBox::paintBackgroundWithBorderAndBoxShadow(PaintInfo& paintInfo, const LayoutRect& paintRect, BackgroundBleedAvoidance bleedAvoidance)
{
    // If we have a native theme appearance, paint that before painting our background.
    // The theme will tell us whether or not we should also paint the CSS background.
    IntRect snappedPaintRect(pixelSnappedIntRect(paintRect));
    bool themePainted = style()->hasAppearance() && !RenderTheme::theme().paint(this, paintInfo, snappedPaintRect);
    if (!themePainted) {
        if (bleedAvoidance == BackgroundBleedBackgroundOverBorder)
            paintBorder(paintInfo, paintRect, style(), bleedAvoidance);

        paintBackground(paintInfo, paintRect, bleedAvoidance);

        if (style()->hasAppearance())
            RenderTheme::theme().paintDecorations(this, paintInfo, snappedPaintRect);
    }
    paintBoxShadow(paintInfo, paintRect, style(), Inset);

    // The theme will tell us whether or not we should also paint the CSS border.
    if (bleedAvoidance != BackgroundBleedBackgroundOverBorder && (!style()->hasAppearance() || (!themePainted && RenderTheme::theme().paintBorderOnly(this, paintInfo, snappedPaintRect))) && style()->hasBorder() && !(isTable() && toRenderTable(this)->collapseBorders()))
        paintBorder(paintInfo, paintRect, style(), bleedAvoidance);
}

void RenderBox::paintBackground(const PaintInfo& paintInfo, const LayoutRect& paintRect, BackgroundBleedAvoidance bleedAvoidance)
{
    if (isRoot()) {
        paintRootBoxFillLayers(paintInfo);
        return;
    }
    if (isBody() && skipBodyBackground(this))
        return;
    if (backgroundIsKnownToBeObscured())
        return;
    paintFillLayers(paintInfo, resolveColor(CSSPropertyBackgroundColor), style()->backgroundLayers(), paintRect, bleedAvoidance);
}

bool RenderBox::getBackgroundPaintedExtent(LayoutRect& paintedExtent) const
{
    ASSERT(hasBackground());
    LayoutRect backgroundRect = pixelSnappedIntRect(borderBoxRect());

    Color backgroundColor = resolveColor(CSSPropertyBackgroundColor);
    if (backgroundColor.alpha()) {
        paintedExtent = backgroundRect;
        return true;
    }

    if (!style()->backgroundLayers()->image() || style()->backgroundLayers()->next()) {
        paintedExtent =  backgroundRect;
        return true;
    }

    BackgroundImageGeometry geometry;
    calculateBackgroundImageGeometry(0, style()->backgroundLayers(), backgroundRect, geometry);
    if (geometry.hasNonLocalGeometry())
        return false;
    paintedExtent = geometry.destRect();
    return true;
}

bool RenderBox::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
{
    if (isBody() && skipBodyBackground(this))
        return false;

    Color backgroundColor = resolveColor(CSSPropertyBackgroundColor);
    if (backgroundColor.hasAlpha())
        return false;

    // If the element has appearance, it might be painted by theme.
    // We cannot be sure if theme paints the background opaque.
    // In this case it is safe to not assume opaqueness.
    // FIXME: May be ask theme if it paints opaque.
    if (style()->hasAppearance())
        return false;
    // FIXME: Check the opaqueness of background images.

    // FIXME: Use rounded rect if border radius is present.
    if (style()->hasBorderRadius())
        return false;
    // FIXME: The background color clip is defined by the last layer.
    if (style()->backgroundLayers()->next())
        return false;
    LayoutRect backgroundRect;
    switch (style()->backgroundClip()) {
    case BorderFillBox:
        backgroundRect = borderBoxRect();
        break;
    case PaddingFillBox:
        backgroundRect = paddingBoxRect();
        break;
    case ContentFillBox:
        backgroundRect = contentBoxRect();
        break;
    default:
        break;
    }
    return backgroundRect.contains(localRect);
}

static bool isCandidateForOpaquenessTest(RenderBox* childBox)
{
    RenderStyle* childStyle = childBox->style();
    if (childStyle->position() != StaticPosition && childBox->containingBlock() != childBox->parent())
        return false;
    if (childStyle->visibility() != VISIBLE || childStyle->shapeOutside())
        return false;
    if (!childBox->width() || !childBox->height())
        return false;
    if (RenderLayer* childLayer = childBox->layer()) {
        // FIXME: perhaps this could be less conservative?
        if (childLayer->compositingState() != NotComposited)
            return false;
        // FIXME: Deal with z-index.
        if (!childStyle->hasAutoZIndex())
            return false;
        if (childLayer->hasTransform() || childLayer->isTransparent() || childLayer->hasFilter())
            return false;
        if (childBox->hasOverflowClip() && childStyle->hasBorderRadius())
            return false;
    }
    return true;
}

bool RenderBox::foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const
{
    if (!maxDepthToTest)
        return false;
    for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
        if (!child->isBox())
            continue;
        RenderBox* childBox = toRenderBox(child);
        if (!isCandidateForOpaquenessTest(childBox))
            continue;
        LayoutPoint childLocation = childBox->location();
        if (childBox->isRelPositioned())
            childLocation.move(childBox->relativePositionOffset());
        LayoutRect childLocalRect = localRect;
        childLocalRect.moveBy(-childLocation);
        if (childLocalRect.y() < 0 || childLocalRect.x() < 0) {
            // If there is unobscured area above/left of a static positioned box then the rect is probably not covered.
            if (childBox->style()->position() == StaticPosition)
                return false;
            continue;
        }
        if (childLocalRect.maxY() > childBox->height() || childLocalRect.maxX() > childBox->width())
            continue;
        if (childBox->backgroundIsKnownToBeOpaqueInRect(childLocalRect))
            return true;
        if (childBox->foregroundIsKnownToBeOpaqueInRect(childLocalRect, maxDepthToTest - 1))
            return true;
    }
    return false;
}

bool RenderBox::computeBackgroundIsKnownToBeObscured()
{
    // Test to see if the children trivially obscure the background.
    // FIXME: This test can be much more comprehensive.
    if (!hasBackground())
        return false;
    // Table and root background painting is special.
    if (isTable() || isRoot())
        return false;
    // FIXME: box-shadow is painted while background painting.
    if (style()->boxShadow())
        return false;
    LayoutRect backgroundRect;
    if (!getBackgroundPaintedExtent(backgroundRect))
        return false;
    return foregroundIsKnownToBeOpaqueInRect(backgroundRect, backgroundObscurationTestMaxDepth);
}

bool RenderBox::backgroundHasOpaqueTopLayer() const
{
    const FillLayer* fillLayer = style()->backgroundLayers();
    if (!fillLayer || fillLayer->clip() != BorderFillBox)
        return false;

    // Clipped with local scrolling
    if (hasOverflowClip() && fillLayer->attachment() == LocalBackgroundAttachment)
        return false;

    if (fillLayer->hasOpaqueImage(this) && fillLayer->hasRepeatXY() && fillLayer->image()->canRender(this, style()->effectiveZoom()))
        return true;

    // If there is only one layer and no image, check whether the background color is opaque
    if (!fillLayer->next() && !fillLayer->hasImage()) {
        Color bgColor = resolveColor(CSSPropertyBackgroundColor);
        if (bgColor.alpha() == 255)
            return true;
    }

    return false;
}

void RenderBox::paintMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    if (!paintInfo.shouldPaintWithinRoot(this) || style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseMask || paintInfo.context->paintingDisabled())
        return;

    LayoutRect paintRect = LayoutRect(paintOffset, size());
    paintMaskImages(paintInfo, paintRect);
}

void RenderBox::paintClippingMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    if (!paintInfo.shouldPaintWithinRoot(this) || style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseClippingMask || paintInfo.context->paintingDisabled())
        return;

    if (!layer() || layer()->compositingState() != PaintsIntoOwnBacking)
        return;

    // We should never have this state in this function. A layer with a mask
    // should have always created its own backing if it became composited.
    ASSERT(layer()->compositingState() != HasOwnBackingButPaintsIntoAncestor);

    LayoutRect paintRect = LayoutRect(paintOffset, size());
    paintInfo.context->fillRect(pixelSnappedIntRect(paintRect), Color::black);
}

void RenderBox::paintMaskImages(const PaintInfo& paintInfo, const LayoutRect& paintRect)
{
    // Figure out if we need to push a transparency layer to render our mask.
    bool pushTransparencyLayer = false;
    bool compositedMask = hasLayer() && layer()->hasCompositedMask();
    bool flattenCompositingLayers = view()->frameView() && view()->frameView()->paintBehavior() & PaintBehaviorFlattenCompositingLayers;
    CompositeOperator compositeOp = CompositeSourceOver;

    bool allMaskImagesLoaded = true;

    if (!compositedMask || flattenCompositingLayers) {
        pushTransparencyLayer = true;
        StyleImage* maskBoxImage = style()->maskBoxImage().image();
        const FillLayer* maskLayers = style()->maskLayers();

        // Don't render a masked element until all the mask images have loaded, to prevent a flash of unmasked content.
        if (maskBoxImage)
            allMaskImagesLoaded &= maskBoxImage->isLoaded();

        if (maskLayers)
            allMaskImagesLoaded &= maskLayers->imagesAreLoaded();

        paintInfo.context->setCompositeOperation(CompositeDestinationIn);
        paintInfo.context->beginTransparencyLayer(1);
        compositeOp = CompositeSourceOver;
    }

    if (allMaskImagesLoaded) {
        paintFillLayers(paintInfo, Color::transparent, style()->maskLayers(), paintRect, BackgroundBleedNone, compositeOp);
        paintNinePieceImage(paintInfo.context, paintRect, style(), style()->maskBoxImage(), compositeOp);
    }

    if (pushTransparencyLayer)
        paintInfo.context->endLayer();
}

LayoutRect RenderBox::maskClipRect()
{
    const NinePieceImage& maskBoxImage = style()->maskBoxImage();
    if (maskBoxImage.image()) {
        LayoutRect borderImageRect = borderBoxRect();

        // Apply outsets to the border box.
        borderImageRect.expand(style()->maskBoxImageOutsets());
        return borderImageRect;
    }

    LayoutRect result;
    LayoutRect borderBox = borderBoxRect();
    for (const FillLayer* maskLayer = style()->maskLayers(); maskLayer; maskLayer = maskLayer->next()) {
        if (maskLayer->image()) {
            BackgroundImageGeometry geometry;
            // Masks should never have fixed attachment, so it's OK for paintContainer to be null.
            calculateBackgroundImageGeometry(0, maskLayer, borderBox, geometry);
            result.unite(geometry.destRect());
        }
    }
    return result;
}

void RenderBox::paintFillLayers(const PaintInfo& paintInfo, const Color& c, const FillLayer* fillLayer, const LayoutRect& rect,
    BackgroundBleedAvoidance bleedAvoidance, CompositeOperator op, RenderObject* backgroundObject)
{
    Vector<const FillLayer*, 8> layers;
    const FillLayer* curLayer = fillLayer;
    bool shouldDrawBackgroundInSeparateBuffer = false;
    while (curLayer) {
        layers.append(curLayer);
        // Stop traversal when an opaque layer is encountered.
        // FIXME : It would be possible for the following occlusion culling test to be more aggressive
        // on layers with no repeat by testing whether the image covers the layout rect.
        // Testing that here would imply duplicating a lot of calculations that are currently done in
        // RenderBoxModelObject::paintFillLayerExtended. A more efficient solution might be to move
        // the layer recursion into paintFillLayerExtended, or to compute the layer geometry here
        // and pass it down.

        if (!shouldDrawBackgroundInSeparateBuffer && curLayer->blendMode() != blink::WebBlendModeNormal)
            shouldDrawBackgroundInSeparateBuffer = true;

        // The clipOccludesNextLayers condition must be evaluated first to avoid short-circuiting.
        if (curLayer->clipOccludesNextLayers(curLayer == fillLayer) && curLayer->hasOpaqueImage(this) && curLayer->image()->canRender(this, style()->effectiveZoom()) && curLayer->hasRepeatXY() && curLayer->blendMode() == blink::WebBlendModeNormal && !boxShadowShouldBeAppliedToBackground(bleedAvoidance))
            break;
        curLayer = curLayer->next();
    }

    GraphicsContext* context = paintInfo.context;
    if (!context)
        shouldDrawBackgroundInSeparateBuffer = false;
    if (shouldDrawBackgroundInSeparateBuffer)
        context->beginTransparencyLayer(1);

    Vector<const FillLayer*>::const_reverse_iterator topLayer = layers.rend();
    for (Vector<const FillLayer*>::const_reverse_iterator it = layers.rbegin(); it != topLayer; ++it)
        paintFillLayer(paintInfo, c, *it, rect, bleedAvoidance, op, backgroundObject);

    if (shouldDrawBackgroundInSeparateBuffer)
        context->endLayer();
}

void RenderBox::paintFillLayer(const PaintInfo& paintInfo, const Color& c, const FillLayer* fillLayer, const LayoutRect& rect,
    BackgroundBleedAvoidance bleedAvoidance, CompositeOperator op, RenderObject* backgroundObject)
{
    paintFillLayerExtended(paintInfo, c, fillLayer, rect, bleedAvoidance, 0, LayoutSize(), op, backgroundObject);
}

static bool layersUseImage(WrappedImagePtr image, const FillLayer* layers)
{
    for (const FillLayer* curLayer = layers; curLayer; curLayer = curLayer->next()) {
        if (curLayer->image() && image == curLayer->image()->data())
            return true;
    }

    return false;
}

void RenderBox::imageChanged(WrappedImagePtr image, const IntRect*)
{
    if (!parent())
        return;

    AllowRepaintScope scoper(frameView());

    if ((style()->borderImage().image() && style()->borderImage().image()->data() == image) ||
        (style()->maskBoxImage().image() && style()->maskBoxImage().image()->data() == image)) {
        repaint();
        return;
    }

    ShapeValue* shapeOutsideValue = style()->shapeOutside();
    if (!frameView()->isInPerformLayout() && isFloating() && shapeOutsideValue && shapeOutsideValue->image() && shapeOutsideValue->image()->data() == image) {
        ShapeOutsideInfo::ensureInfo(*this).markShapeAsDirty();
        markShapeOutsideDependentsForLayout();
    }

    bool didFullRepaint = repaintLayerRectsForImage(image, style()->backgroundLayers(), true);
    if (!didFullRepaint)
        repaintLayerRectsForImage(image, style()->maskLayers(), false);

    if (hasLayer() && layer()->hasCompositedMask() && layersUseImage(image, style()->maskLayers()))
        layer()->contentChanged(MaskImageChanged);
}

bool RenderBox::repaintLayerRectsForImage(WrappedImagePtr image, const FillLayer* layers, bool drawingBackground)
{
    LayoutRect rendererRect;
    RenderBox* layerRenderer = 0;

    for (const FillLayer* curLayer = layers; curLayer; curLayer = curLayer->next()) {
        if (curLayer->image() && image == curLayer->image()->data() && curLayer->image()->canRender(this, style()->effectiveZoom())) {
            // Now that we know this image is being used, compute the renderer and the rect if we haven't already.
            if (!layerRenderer) {
                bool drawingRootBackground = drawingBackground && (isRoot() || (isBody() && !document().documentElement()->renderer()->hasBackground()));
                if (drawingRootBackground) {
                    layerRenderer = view();

                    LayoutUnit rw;
                    LayoutUnit rh;

                    if (FrameView* frameView = toRenderView(layerRenderer)->frameView()) {
                        rw = frameView->contentsWidth();
                        rh = frameView->contentsHeight();
                    } else {
                        rw = layerRenderer->width();
                        rh = layerRenderer->height();
                    }
                    rendererRect = LayoutRect(-layerRenderer->marginLeft(),
                        -layerRenderer->marginTop(),
                        max(layerRenderer->width() + layerRenderer->marginWidth() + layerRenderer->borderLeft() + layerRenderer->borderRight(), rw),
                        max(layerRenderer->height() + layerRenderer->marginHeight() + layerRenderer->borderTop() + layerRenderer->borderBottom(), rh));
                } else {
                    layerRenderer = this;
                    rendererRect = borderBoxRect();
                }
            }

            BackgroundImageGeometry geometry;
            layerRenderer->calculateBackgroundImageGeometry(0, curLayer, rendererRect, geometry);
            if (geometry.hasNonLocalGeometry()) {
                // Rather than incur the costs of computing the paintContainer for renderers with fixed backgrounds
                // in order to get the right destRect, just repaint the entire renderer.
                layerRenderer->repaint();
                return true;
            }

            layerRenderer->repaintRectangle(geometry.destRect());
            if (geometry.destRect() == rendererRect)
                return true;
        }
    }
    return false;
}

bool RenderBox::pushContentsClip(PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset, ContentsClipBehavior contentsClipBehavior)
{
    if (paintInfo.phase == PaintPhaseBlockBackground || paintInfo.phase == PaintPhaseSelfOutline || paintInfo.phase == PaintPhaseMask)
        return false;

    bool isControlClip = hasControlClip();
    bool isOverflowClip = hasOverflowClip() && !layer()->isSelfPaintingLayer();

    if (!isControlClip && !isOverflowClip)
        return false;

    LayoutRect clipRect = isControlClip ? controlClipRect(accumulatedOffset) : overflowClipRect(accumulatedOffset);
    RoundedRect clipRoundedRect(0, 0, 0, 0);
    bool hasBorderRadius = style()->hasBorderRadius();
    if (hasBorderRadius)
        clipRoundedRect = style()->getRoundedInnerBorderFor(LayoutRect(accumulatedOffset, size()));

    if (contentsClipBehavior == SkipContentsClipIfPossible) {
        LayoutRect contentsVisualOverflow = contentsVisualOverflowRect();
        if (contentsVisualOverflow.isEmpty())
            return false;

        LayoutRect conservativeClipRect = clipRect;
        if (hasBorderRadius)
            conservativeClipRect.intersect(clipRoundedRect.radiusCenterRect());
        conservativeClipRect.moveBy(-accumulatedOffset);
        if (hasLayer())
            conservativeClipRect.move(scrolledContentOffset());
        if (conservativeClipRect.contains(contentsVisualOverflow))
            return false;
    }

    if (paintInfo.phase == PaintPhaseOutline)
        paintInfo.phase = PaintPhaseChildOutlines;
    else if (paintInfo.phase == PaintPhaseChildBlockBackground) {
        paintInfo.phase = PaintPhaseBlockBackground;
        paintObject(paintInfo, accumulatedOffset);
        paintInfo.phase = PaintPhaseChildBlockBackgrounds;
    }
    paintInfo.context->save();
    if (hasBorderRadius)
        paintInfo.context->clipRoundedRect(clipRoundedRect);
    paintInfo.context->clip(pixelSnappedIntRect(clipRect));
    return true;
}

void RenderBox::popContentsClip(PaintInfo& paintInfo, PaintPhase originalPhase, const LayoutPoint& accumulatedOffset)
{
    ASSERT(hasControlClip() || (hasOverflowClip() && !layer()->isSelfPaintingLayer()));

    paintInfo.context->restore();
    if (originalPhase == PaintPhaseOutline) {
        paintInfo.phase = PaintPhaseSelfOutline;
        paintObject(paintInfo, accumulatedOffset);
        paintInfo.phase = originalPhase;
    } else if (originalPhase == PaintPhaseChildBlockBackground)
        paintInfo.phase = originalPhase;
}

LayoutRect RenderBox::overflowClipRect(const LayoutPoint& location, OverlayScrollbarSizeRelevancy relevancy)
{
    // FIXME: When overflow-clip (CSS3) is implemented, we'll obtain the property
    // here.
    LayoutRect clipRect = borderBoxRect();
    clipRect.setLocation(location + clipRect.location() + LayoutSize(borderLeft(), borderTop()));
    clipRect.setSize(clipRect.size() - LayoutSize(borderLeft() + borderRight(), borderTop() + borderBottom()));

    if (!hasOverflowClip())
        return clipRect;

    // Subtract out scrollbars if we have them.
    if (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
        clipRect.move(layer()->scrollableArea()->verticalScrollbarWidth(relevancy), 0);
    clipRect.contract(layer()->scrollableArea()->verticalScrollbarWidth(relevancy), layer()->scrollableArea()->horizontalScrollbarHeight(relevancy));

    return clipRect;
}

LayoutRect RenderBox::clipRect(const LayoutPoint& location)
{
    LayoutRect borderBoxRect = this->borderBoxRect();
    LayoutRect clipRect = LayoutRect(borderBoxRect.location() + location, borderBoxRect.size());

    if (!style()->clipLeft().isAuto()) {
        LayoutUnit c = valueForLength(style()->clipLeft(), borderBoxRect.width());
        clipRect.move(c, 0);
        clipRect.contract(c, 0);
    }

    if (!style()->clipRight().isAuto())
        clipRect.contract(width() - valueForLength(style()->clipRight(), width()), 0);

    if (!style()->clipTop().isAuto()) {
        LayoutUnit c = valueForLength(style()->clipTop(), borderBoxRect.height());
        clipRect.move(0, c);
        clipRect.contract(0, c);
    }

    if (!style()->clipBottom().isAuto())
        clipRect.contract(0, height() - valueForLength(style()->clipBottom(), height()));

    return clipRect;
}

LayoutUnit RenderBox::shrinkLogicalWidthToAvoidFloats(LayoutUnit childMarginStart, LayoutUnit childMarginEnd, const RenderBlockFlow* cb) const
{
    LayoutUnit logicalTopPosition = logicalTop();
    LayoutUnit result = cb->availableLogicalWidthForLine(logicalTopPosition, false) - childMarginStart - childMarginEnd;

    // We need to see if margins on either the start side or the end side can contain the floats in question. If they can,
    // then just using the line width is inaccurate. In the case where a float completely fits, we don't need to use the line
    // offset at all, but can instead push all the way to the content edge of the containing block. In the case where the float
    // doesn't fit, we can use the line offset, but we need to grow it by the margin to reflect the fact that the margin was
    // "consumed" by the float. Negative margins aren't consumed by the float, and so we ignore them.
    if (childMarginStart > 0) {
        LayoutUnit startContentSide = cb->startOffsetForContent();
        LayoutUnit startContentSideWithMargin = startContentSide + childMarginStart;
        LayoutUnit startOffset = cb->startOffsetForLine(logicalTopPosition, false);
        if (startOffset > startContentSideWithMargin)
            result += childMarginStart;
        else
            result += startOffset - startContentSide;
    }

    if (childMarginEnd > 0) {
        LayoutUnit endContentSide = cb->endOffsetForContent();
        LayoutUnit endContentSideWithMargin = endContentSide + childMarginEnd;
        LayoutUnit endOffset = cb->endOffsetForLine(logicalTopPosition, false);
        if (endOffset > endContentSideWithMargin)
            result += childMarginEnd;
        else
            result += endOffset - endContentSide;
    }

    return result;
}

LayoutUnit RenderBox::containingBlockLogicalWidthForContent() const
{
    if (hasOverrideContainingBlockLogicalWidth())
        return overrideContainingBlockContentLogicalWidth();

    RenderBlock* cb = containingBlock();
    return cb->availableLogicalWidth();
}

LayoutUnit RenderBox::containingBlockLogicalHeightForContent(AvailableLogicalHeightType heightType) const
{
    if (hasOverrideContainingBlockLogicalHeight())
        return overrideContainingBlockContentLogicalHeight();

    RenderBlock* cb = containingBlock();
    return cb->availableLogicalHeight(heightType);
}

LayoutUnit RenderBox::containingBlockAvailableLineWidth() const
{
    RenderBlock* cb = containingBlock();
    if (cb->isRenderBlockFlow())
        return toRenderBlockFlow(cb)->availableLogicalWidthForLine(logicalTop(), false, availableLogicalHeight(IncludeMarginBorderPadding));
    return 0;
}

LayoutUnit RenderBox::perpendicularContainingBlockLogicalHeight() const
{
    if (hasOverrideContainingBlockLogicalHeight())
        return overrideContainingBlockContentLogicalHeight();

    RenderBlock* cb = containingBlock();
    if (cb->hasOverrideHeight())
        return cb->overrideLogicalContentHeight();

    RenderStyle* containingBlockStyle = cb->style();
    Length logicalHeightLength = containingBlockStyle->logicalHeight();

    // FIXME: For now just support fixed heights.  Eventually should support percentage heights as well.
    if (!logicalHeightLength.isFixed()) {
        LayoutUnit fillFallbackExtent = containingBlockStyle->isHorizontalWritingMode() ? view()->frameView()->visibleHeight() : view()->frameView()->visibleWidth();
        LayoutUnit fillAvailableExtent = containingBlock()->availableLogicalHeight(ExcludeMarginBorderPadding);
        return min(fillAvailableExtent, fillFallbackExtent);
    }

    // Use the content box logical height as specified by the style.
    return cb->adjustContentBoxLogicalHeightForBoxSizing(logicalHeightLength.value());
}

void RenderBox::mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState& transformState, MapCoordinatesFlags mode, bool* wasFixed) const
{
    if (repaintContainer == this)
        return;

    if (RenderView* v = view()) {
        if (v->layoutStateEnabled() && !repaintContainer) {
            LayoutState* layoutState = v->layoutState();
            LayoutSize offset = layoutState->paintOffset() + locationOffset();
            if (style()->hasInFlowPosition() && layer())
                offset += layer()->offsetForInFlowPosition();
            transformState.move(offset);
            return;
        }
    }

    bool containerSkipped;
    RenderObject* o = container(repaintContainer, &containerSkipped);
    if (!o)
        return;

    bool isFixedPos = style()->position() == FixedPosition;
    bool hasTransform = hasLayer() && layer()->transform();
    // If this box has a transform, it acts as a fixed position container for fixed descendants,
    // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
    if (hasTransform && !isFixedPos)
        mode &= ~IsFixed;
    else if (isFixedPos)
        mode |= IsFixed;

    if (wasFixed)
        *wasFixed = mode & IsFixed;

    LayoutSize containerOffset = offsetFromContainer(o, roundedLayoutPoint(transformState.mappedPoint()));

    bool preserve3D = mode & UseTransforms && (o->style()->preserves3D() || style()->preserves3D());
    if (mode & UseTransforms && shouldUseTransformFromContainer(o)) {
        TransformationMatrix t;
        getTransformFromContainer(o, containerOffset, t);
        transformState.applyTransform(t, preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
    } else
        transformState.move(containerOffset.width(), containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);

    if (containerSkipped) {
        // There can't be a transform between repaintContainer and o, because transforms create containers, so it should be safe
        // to just subtract the delta between the repaintContainer and o.
        LayoutSize containerOffset = repaintContainer->offsetFromAncestorContainer(o);
        transformState.move(-containerOffset.width(), -containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
        return;
    }

    mode &= ~ApplyContainerFlip;

    o->mapLocalToContainer(repaintContainer, transformState, mode, wasFixed);
}

void RenderBox::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, TransformState& transformState) const
{
    // We don't expect to be called during layout.
    ASSERT(!view() || !view()->layoutStateEnabled());

    bool isFixedPos = style()->position() == FixedPosition;
    bool hasTransform = hasLayer() && layer()->transform();
    if (hasTransform && !isFixedPos) {
        // If this box has a transform, it acts as a fixed position container for fixed descendants,
        // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
        mode &= ~IsFixed;
    } else if (isFixedPos)
        mode |= IsFixed;

    RenderBoxModelObject::mapAbsoluteToLocalPoint(mode, transformState);
}

LayoutSize RenderBox::offsetFromContainer(RenderObject* o, const LayoutPoint& point, bool* offsetDependsOnPoint) const
{
    ASSERT(o == container());

    LayoutSize offset;
    if (isInFlowPositioned())
        offset += offsetForInFlowPosition();

    if (!isInline() || isReplaced()) {
        if (!style()->hasOutOfFlowPosition() && o->hasColumns()) {
            RenderBlock* block = toRenderBlock(o);
            LayoutRect columnRect(frameRect());
            block->adjustStartEdgeForWritingModeIncludingColumns(columnRect);
            offset += toSize(columnRect.location());
            LayoutPoint columnPoint = block->flipForWritingModeIncludingColumns(point + offset);
            offset = toLayoutSize(block->flipForWritingModeIncludingColumns(toLayoutPoint(offset)));
            o->adjustForColumns(offset, columnPoint);
            offset = block->flipForWritingMode(offset);

            if (offsetDependsOnPoint)
                *offsetDependsOnPoint = true;
        } else
            offset += topLeftLocationOffset();
    }

    if (o->hasOverflowClip())
        offset -= toRenderBox(o)->scrolledContentOffset();

    if (style()->position() == AbsolutePosition && o->isInFlowPositioned() && o->isRenderInline())
        offset += toRenderInline(o)->offsetForInFlowPositionedInline(*this);

    if (offsetDependsOnPoint)
        *offsetDependsOnPoint |= o->isRenderFlowThread();

    return offset;
}

InlineBox* RenderBox::createInlineBox()
{
    return new InlineBox(*this);
}

void RenderBox::dirtyLineBoxes(bool fullLayout)
{
    if (inlineBoxWrapper()) {
        if (fullLayout) {
            inlineBoxWrapper()->destroy();
            ASSERT(m_rareData);
            m_rareData->m_inlineBoxWrapper = 0;
        } else {
            inlineBoxWrapper()->dirtyLineBoxes();
        }
    }
}

void RenderBox::positionLineBox(InlineBox* box)
{
    if (isOutOfFlowPositioned()) {
        // Cache the x position only if we were an INLINE type originally.
        bool wasInline = style()->isOriginalDisplayInlineType();
        if (wasInline) {
            // The value is cached in the xPos of the box.  We only need this value if
            // our object was inline originally, since otherwise it would have ended up underneath
            // the inlines.
            RootInlineBox& root = box->root();
            root.block().setStaticInlinePositionForChild(this, root.lineTopWithLeading(), LayoutUnit::fromFloatRound(box->logicalLeft()));
            if (style()->hasStaticInlinePosition(box->isHorizontal()))
                setChildNeedsLayout(MarkOnlyThis); // Just go ahead and mark the positioned object as needing layout, so it will update its position properly.
        } else {
            // Our object was a block originally, so we make our normal flow position be
            // just below the line box (as though all the inlines that came before us got
            // wrapped in an anonymous block, which is what would have happened had we been
            // in flow).  This value was cached in the y() of the box.
            layer()->setStaticBlockPosition(box->logicalTop());
            if (style()->hasStaticBlockPosition(box->isHorizontal()))
                setChildNeedsLayout(MarkOnlyThis); // Just go ahead and mark the positioned object as needing layout, so it will update its position properly.
        }

        // Nuke the box.
        box->remove();
        box->destroy();
    } else if (isReplaced()) {
        setLocation(roundedLayoutPoint(box->topLeft()));
        setInlineBoxWrapper(box);
    }
}

void RenderBox::deleteLineBoxWrapper()
{
    if (inlineBoxWrapper()) {
        if (!documentBeingDestroyed())
            inlineBoxWrapper()->remove();
        inlineBoxWrapper()->destroy();
        ASSERT(m_rareData);
        m_rareData->m_inlineBoxWrapper = 0;
    }
}

LayoutRect RenderBox::clippedOverflowRectForRepaint(const RenderLayerModelObject* repaintContainer) const
{
    if (style()->visibility() != VISIBLE && !enclosingLayer()->hasVisibleContent())
        return LayoutRect();

    LayoutRect r = visualOverflowRect();

    RenderView* v = view();
    if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled() && v) {
        // FIXME: layoutDelta needs to be applied in parts before/after transforms and
        // repaint containers. https://bugs.webkit.org/show_bug.cgi?id=23308
        r.move(v->layoutDelta());
    }

    computeRectForRepaint(repaintContainer, r);
    return r;
}

void RenderBox::computeRectForRepaint(const RenderLayerModelObject* repaintContainer, LayoutRect& rect, bool fixed) const
{
    // The rect we compute at each step is shifted by our x/y offset in the parent container's coordinate space.
    // Only when we cross a writing mode boundary will we have to possibly flipForWritingMode (to convert into a more appropriate
    // offset corner for the enclosing container).  This allows for a fully RL or BT document to repaint
    // properly even during layout, since the rect remains flipped all the way until the end.
    //
    // RenderView::computeRectForRepaint then converts the rect to physical coordinates.  We also convert to
    // physical when we hit a repaintContainer boundary.  Therefore the final rect returned is always in the
    // physical coordinate space of the repaintContainer.
    RenderStyle* styleToUse = style();
    if (RenderView* v = view()) {
        // LayoutState is only valid for root-relative, non-fixed position repainting
        if (v->layoutStateEnabled() && !repaintContainer && styleToUse->position() != FixedPosition) {
            LayoutState* layoutState = v->layoutState();

            if (layer() && layer()->transform())
                rect = layer()->transform()->mapRect(pixelSnappedIntRect(rect));

            // We can't trust the bits on RenderObject, because this might be called while re-resolving style.
            if (styleToUse->hasInFlowPosition() && layer())
                rect.move(layer()->offsetForInFlowPosition());

            rect.moveBy(location());
            rect.move(layoutState->paintOffset());
            if (layoutState->isClipped())
                rect.intersect(layoutState->clipRect());
            return;
        }
    }

    if (hasReflection())
        rect.unite(reflectedRect(rect));

    if (repaintContainer == this) {
        if (repaintContainer->style()->isFlippedBlocksWritingMode())
            flipForWritingMode(rect);
        return;
    }

    bool containerSkipped;
    RenderObject* o = container(repaintContainer, &containerSkipped);
    if (!o)
        return;

    if (isWritingModeRoot() && !isOutOfFlowPositioned())
        flipForWritingMode(rect);

    LayoutPoint topLeft = rect.location();
    topLeft.move(locationOffset());

    EPosition position = styleToUse->position();

    // We are now in our parent container's coordinate space.  Apply our transform to obtain a bounding box
    // in the parent's coordinate space that encloses us.
    if (hasLayer() && layer()->transform()) {
        fixed = position == FixedPosition;
        rect = layer()->transform()->mapRect(pixelSnappedIntRect(rect));
        topLeft = rect.location();
        topLeft.move(locationOffset());
    } else if (position == FixedPosition)
        fixed = true;

    if (position == AbsolutePosition && o->isInFlowPositioned() && o->isRenderInline()) {
        topLeft += toRenderInline(o)->offsetForInFlowPositionedInline(*this);
    } else if (styleToUse->hasInFlowPosition() && layer()) {
        // Apply the relative position offset when invalidating a rectangle.  The layer
        // is translated, but the render box isn't, so we need to do this to get the
        // right dirty rect.  Since this is called from RenderObject::setStyle, the relative position
        // flag on the RenderObject has been cleared, so use the one on the style().
        topLeft += layer()->offsetForInFlowPosition();
    }

    if (position != AbsolutePosition && position != FixedPosition && o->hasColumns() && o->isRenderBlockFlow()) {
        LayoutRect repaintRect(topLeft, rect.size());
        toRenderBlock(o)->adjustRectForColumns(repaintRect);
        topLeft = repaintRect.location();
        rect = repaintRect;
    }

    // FIXME: We ignore the lightweight clipping rect that controls use, since if |o| is in mid-layout,
    // its controlClipRect will be wrong. For overflow clip we use the values cached by the layer.
    rect.setLocation(topLeft);
    if (o->hasOverflowClip()) {
        RenderBox* containerBox = toRenderBox(o);
        containerBox->applyCachedClipAndScrollOffsetForRepaint(rect);
        if (rect.isEmpty())
            return;
    }

    if (containerSkipped) {
        // If the repaintContainer is below o, then we need to map the rect into repaintContainer's coordinates.
        LayoutSize containerOffset = repaintContainer->offsetFromAncestorContainer(o);
        rect.move(-containerOffset);
        return;
    }

    o->computeRectForRepaint(repaintContainer, rect, fixed);
}

void RenderBox::repaintDuringLayoutIfMoved(const LayoutRect& oldRect)
{
    if (oldRect.location() != m_frameRect.location()) {
        LayoutRect newRect = m_frameRect;
        // The child moved.  Invalidate the object's old and new positions.  We have to do this
        // since the object may not have gotten a layout.
        m_frameRect = oldRect;
        repaint();
        repaintOverhangingFloats(true);
        m_frameRect = newRect;
        repaint();
        repaintOverhangingFloats(true);
    }
}

void RenderBox::repaintOverhangingFloats(bool)
{
}

void RenderBox::updateLogicalWidth()
{
    LogicalExtentComputedValues computedValues;
    computeLogicalWidth(computedValues);

    setLogicalWidth(computedValues.m_extent);
    setLogicalLeft(computedValues.m_position);
    setMarginStart(computedValues.m_margins.m_start);
    setMarginEnd(computedValues.m_margins.m_end);
}

static float getMaxWidthListMarker(const RenderBox* renderer)
{
#ifndef NDEBUG
    ASSERT(renderer);
    Node* parentNode = renderer->generatingNode();
    ASSERT(parentNode);
    ASSERT(isHTMLOListElement(parentNode) || isHTMLUListElement(parentNode));
    ASSERT(renderer->style()->textAutosizingMultiplier() != 1);
#endif
    float maxWidth = 0;
    for (RenderObject* child = renderer->firstChild(); child; child = child->nextSibling()) {
        if (!child->isListItem())
            continue;

        RenderBox* listItem = toRenderBox(child);
        for (RenderObject* itemChild = listItem->firstChild(); itemChild; itemChild = itemChild->nextSibling()) {
            if (!itemChild->isListMarker())
                continue;
            RenderBox* itemMarker = toRenderBox(itemChild);
            // FIXME: canDetermineWidthWithoutLayout expects us to use fixedOffsetWidth, which this code
            // does not do! This check is likely wrong.
            if (!itemMarker->canDetermineWidthWithoutLayout() && itemMarker->needsLayout()) {
                // Make sure to compute the autosized width.
                itemMarker->layout();
            }
            maxWidth = max<float>(maxWidth, toRenderListMarker(itemMarker)->logicalWidth().toFloat());
            break;
        }
    }
    return maxWidth;
}

void RenderBox::computeLogicalWidth(LogicalExtentComputedValues& computedValues) const
{
    computedValues.m_extent = logicalWidth();
    computedValues.m_position = logicalLeft();
    computedValues.m_margins.m_start = marginStart();
    computedValues.m_margins.m_end = marginEnd();

    if (isOutOfFlowPositioned()) {
        // FIXME: This calculation is not patched for block-flow yet.
        // https://bugs.webkit.org/show_bug.cgi?id=46500
        computePositionedLogicalWidth(computedValues);
        return;
    }

    // If layout is limited to a subtree, the subtree root's logical width does not change.
    if (node() && view()->frameView() && view()->frameView()->layoutRoot(true) == this)
        return;

    // The parent box is flexing us, so it has increased or decreased our
    // width.  Use the width from the style context.
    // FIXME: Account for block-flow in flexible boxes.
    // https://bugs.webkit.org/show_bug.cgi?id=46418
    if (hasOverrideWidth() && (style()->borderFit() == BorderFitLines || parent()->isFlexibleBoxIncludingDeprecated())) {
        computedValues.m_extent = overrideLogicalContentWidth() + borderAndPaddingLogicalWidth();
        return;
    }

    // FIXME: Account for block-flow in flexible boxes.
    // https://bugs.webkit.org/show_bug.cgi?id=46418
    bool inVerticalBox = parent()->isDeprecatedFlexibleBox() && (parent()->style()->boxOrient() == VERTICAL);
    bool stretching = (parent()->style()->boxAlign() == BSTRETCH);
    bool treatAsReplaced = shouldComputeSizeAsReplaced() && (!inVerticalBox || !stretching);

    RenderStyle* styleToUse = style();
    Length logicalWidthLength = treatAsReplaced ? Length(computeReplacedLogicalWidth(), Fixed) : styleToUse->logicalWidth();

    RenderBlock* cb = containingBlock();
    LayoutUnit containerLogicalWidth = max<LayoutUnit>(0, containingBlockLogicalWidthForContent());
    bool hasPerpendicularContainingBlock = cb->isHorizontalWritingMode() != isHorizontalWritingMode();

    if (isInline() && !isInlineBlockOrInlineTable()) {
        // just calculate margins
        computedValues.m_margins.m_start = minimumValueForLength(styleToUse->marginStart(), containerLogicalWidth);
        computedValues.m_margins.m_end = minimumValueForLength(styleToUse->marginEnd(), containerLogicalWidth);
        if (treatAsReplaced)
            computedValues.m_extent = max<LayoutUnit>(floatValueForLength(logicalWidthLength, 0) + borderAndPaddingLogicalWidth(), minPreferredLogicalWidth());
        return;
    }

    // Width calculations
    if (treatAsReplaced)
        computedValues.m_extent = logicalWidthLength.value() + borderAndPaddingLogicalWidth();
    else {
        LayoutUnit containerWidthInInlineDirection = containerLogicalWidth;
        if (hasPerpendicularContainingBlock)
            containerWidthInInlineDirection = perpendicularContainingBlockLogicalHeight();
        LayoutUnit preferredWidth = computeLogicalWidthUsing(MainOrPreferredSize, styleToUse->logicalWidth(), containerWidthInInlineDirection, cb);
        computedValues.m_extent = constrainLogicalWidthByMinMax(preferredWidth, containerWidthInInlineDirection, cb);
    }

    // Margin calculations.
    if (hasPerpendicularContainingBlock || isFloating() || isInline()) {
        computedValues.m_margins.m_start = minimumValueForLength(styleToUse->marginStart(), containerLogicalWidth);
        computedValues.m_margins.m_end = minimumValueForLength(styleToUse->marginEnd(), containerLogicalWidth);
    } else {
        bool hasInvertedDirection = cb->style()->isLeftToRightDirection() != style()->isLeftToRightDirection();
        computeInlineDirectionMargins(cb, containerLogicalWidth, computedValues.m_extent,
            hasInvertedDirection ? computedValues.m_margins.m_end : computedValues.m_margins.m_start,
            hasInvertedDirection ? computedValues.m_margins.m_start : computedValues.m_margins.m_end);
    }

    if (!hasPerpendicularContainingBlock && containerLogicalWidth && containerLogicalWidth != (computedValues.m_extent + computedValues.m_margins.m_start + computedValues.m_margins.m_end)
        && !isFloating() && !isInline() && !cb->isFlexibleBoxIncludingDeprecated() && !cb->isRenderGrid()) {
        LayoutUnit newMargin = containerLogicalWidth - computedValues.m_extent - cb->marginStartForChild(this);
        bool hasInvertedDirection = cb->style()->isLeftToRightDirection() != style()->isLeftToRightDirection();
        if (hasInvertedDirection)
            computedValues.m_margins.m_start = newMargin;
        else
            computedValues.m_margins.m_end = newMargin;
    }

    if (styleToUse->textAutosizingMultiplier() != 1 && styleToUse->marginStart().type() == Fixed) {
        Node* parentNode = generatingNode();
        if (parentNode && (isHTMLOListElement(*parentNode) || isHTMLUListElement(*parentNode))) {
            // Make sure the markers in a list are properly positioned (i.e. not chopped off) when autosized.
            const float adjustedMargin = (1 - 1.0 / styleToUse->textAutosizingMultiplier()) * getMaxWidthListMarker(this);
            bool hasInvertedDirection = cb->style()->isLeftToRightDirection() != style()->isLeftToRightDirection();
            if (hasInvertedDirection)
                computedValues.m_margins.m_end += adjustedMargin;
            else
                computedValues.m_margins.m_start += adjustedMargin;
        }
    }
}

LayoutUnit RenderBox::fillAvailableMeasure(LayoutUnit availableLogicalWidth) const
{
    LayoutUnit marginStart = 0;
    LayoutUnit marginEnd = 0;
    return fillAvailableMeasure(availableLogicalWidth, marginStart, marginEnd);
}

LayoutUnit RenderBox::fillAvailableMeasure(LayoutUnit availableLogicalWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const
{
    marginStart = minimumValueForLength(style()->marginStart(), availableLogicalWidth);
    marginEnd = minimumValueForLength(style()->marginEnd(), availableLogicalWidth);
    return availableLogicalWidth - marginStart - marginEnd;
}

LayoutUnit RenderBox::computeIntrinsicLogicalWidthUsing(Length logicalWidthLength, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const
{
    if (logicalWidthLength.type() == FillAvailable)
        return fillAvailableMeasure(availableLogicalWidth);

    LayoutUnit minLogicalWidth = 0;
    LayoutUnit maxLogicalWidth = 0;
    computeIntrinsicLogicalWidths(minLogicalWidth, maxLogicalWidth);

    if (logicalWidthLength.type() == MinContent)
        return minLogicalWidth + borderAndPadding;

    if (logicalWidthLength.type() == MaxContent)
        return maxLogicalWidth + borderAndPadding;

    if (logicalWidthLength.type() == FitContent) {
        minLogicalWidth += borderAndPadding;
        maxLogicalWidth += borderAndPadding;
        return max(minLogicalWidth, min(maxLogicalWidth, fillAvailableMeasure(availableLogicalWidth)));
    }

    ASSERT_NOT_REACHED();
    return 0;
}

LayoutUnit RenderBox::computeLogicalWidthUsing(SizeType widthType, Length logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock* cb) const
{
    if (!logicalWidth.isIntrinsicOrAuto()) {
        // FIXME: If the containing block flow is perpendicular to our direction we need to use the available logical height instead.
        return adjustBorderBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, availableLogicalWidth));
    }

    if (logicalWidth.isIntrinsic())
        return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth());

    LayoutUnit marginStart = 0;
    LayoutUnit marginEnd = 0;
    LayoutUnit logicalWidthResult = fillAvailableMeasure(availableLogicalWidth, marginStart, marginEnd);

    if (shrinkToAvoidFloats() && cb->containsFloats())
        logicalWidthResult = min(logicalWidthResult, shrinkLogicalWidthToAvoidFloats(marginStart, marginEnd, toRenderBlockFlow(cb)));

    if (widthType == MainOrPreferredSize && sizesLogicalWidthToFitContent(logicalWidth))
        return max(minPreferredLogicalWidth(), min(maxPreferredLogicalWidth(), logicalWidthResult));
    return logicalWidthResult;
}

static bool columnFlexItemHasStretchAlignment(const RenderObject* flexitem)
{
    RenderObject* parent = flexitem->parent();
    // auto margins mean we don't stretch. Note that this function will only be used for
    // widths, so we don't have to check marginBefore/marginAfter.
    ASSERT(parent->style()->isColumnFlexDirection());
    if (flexitem->style()->marginStart().isAuto() || flexitem->style()->marginEnd().isAuto())
        return false;
    return flexitem->style()->alignSelf() == ItemPositionStretch || (flexitem->style()->alignSelf() == ItemPositionAuto && parent->style()->alignItems() == ItemPositionStretch);
}

static bool isStretchingColumnFlexItem(const RenderObject* flexitem)
{
    RenderObject* parent = flexitem->parent();
    if (parent->isDeprecatedFlexibleBox() && parent->style()->boxOrient() == VERTICAL && parent->style()->boxAlign() == BSTRETCH)
        return true;

    // We don't stretch multiline flexboxes because they need to apply line spacing (align-content) first.
    if (parent->isFlexibleBox() && parent->style()->flexWrap() == FlexNoWrap && parent->style()->isColumnFlexDirection() && columnFlexItemHasStretchAlignment(flexitem))
        return true;
    return false;
}

bool RenderBox::sizesLogicalWidthToFitContent(const Length& logicalWidth) const
{
    // Marquees in WinIE are like a mixture of blocks and inline-blocks.  They size as though they're blocks,
    // but they allow text to sit on the same line as the marquee.
    if (isFloating() || (isInlineBlockOrInlineTable() && !isMarquee()))
        return true;

    if (logicalWidth.type() == Intrinsic)
        return true;

    // Children of a horizontal marquee do not fill the container by default.
    // FIXME: Need to deal with MAUTO value properly.  It could be vertical.
    // FIXME: Think about block-flow here.  Need to find out how marquee direction relates to
    // block-flow (as well as how marquee overflow should relate to block flow).
    // https://bugs.webkit.org/show_bug.cgi?id=46472
    if (parent()->isMarquee()) {
        EMarqueeDirection dir = parent()->style()->marqueeDirection();
        if (dir == MAUTO || dir == MFORWARD || dir == MBACKWARD || dir == MLEFT || dir == MRIGHT)
            return true;
    }

    // Flexible box items should shrink wrap, so we lay them out at their intrinsic widths.
    // In the case of columns that have a stretch alignment, we go ahead and layout at the
    // stretched size to avoid an extra layout when applying alignment.
    if (parent()->isFlexibleBox()) {
        // For multiline columns, we need to apply align-content first, so we can't stretch now.
        if (!parent()->style()->isColumnFlexDirection() || parent()->style()->flexWrap() != FlexNoWrap)
            return true;
        if (!columnFlexItemHasStretchAlignment(this))
            return true;
    }

    // Flexible horizontal boxes lay out children at their intrinsic widths.  Also vertical boxes
    // that don't stretch their kids lay out their children at their intrinsic widths.
    // FIXME: Think about block-flow here.
    // https://bugs.webkit.org/show_bug.cgi?id=46473
    if (parent()->isDeprecatedFlexibleBox() && (parent()->style()->boxOrient() == HORIZONTAL || parent()->style()->boxAlign() != BSTRETCH))
        return true;

    // Button, input, select, textarea, and legend treat width value of 'auto' as 'intrinsic' unless it's in a
    // stretching column flexbox.
    // FIXME: Think about block-flow here.
    // https://bugs.webkit.org/show_bug.cgi?id=46473
    if (logicalWidth.isAuto() && !isStretchingColumnFlexItem(this) && autoWidthShouldFitContent())
        return true;

    if (isHorizontalWritingMode() != containingBlock()->isHorizontalWritingMode())
        return true;

    return false;
}

bool RenderBox::autoWidthShouldFitContent() const
{
    return node() && (isHTMLInputElement(*node()) || isHTMLSelectElement(*node()) || isHTMLButtonElement(*node())
        || isHTMLTextAreaElement(*node()) || (isHTMLLegendElement(*node()) && !style()->hasOutOfFlowPosition()));
}

void RenderBox::computeInlineDirectionMargins(RenderBlock* containingBlock, LayoutUnit containerWidth, LayoutUnit childWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const
{
    const RenderStyle* containingBlockStyle = containingBlock->style();
    Length marginStartLength = style()->marginStartUsing(containingBlockStyle);
    Length marginEndLength = style()->marginEndUsing(containingBlockStyle);

    if (isFloating() || isInline()) {
        // Inline blocks/tables and floats don't have their margins increased.
        marginStart = minimumValueForLength(marginStartLength, containerWidth);
        marginEnd = minimumValueForLength(marginEndLength, containerWidth);
        return;
    }

    if (containingBlock->isFlexibleBox()) {
        // We need to let flexbox handle the margin adjustment - otherwise, flexbox
        // will think we're wider than we actually are and calculate line sizes wrong.
        // See also http://dev.w3.org/csswg/css-flexbox/#auto-margins
        if (marginStartLength.isAuto())
            marginStartLength.setValue(0);
        if (marginEndLength.isAuto())
            marginEndLength.setValue(0);
    }

    LayoutUnit availableWidth = containerWidth;
    if (avoidsFloats() && containingBlock->containsFloats())
        availableWidth = containingBlockAvailableLineWidth();

    // Case One: The object is being centered in the containing block's available logical width.
    if ((marginStartLength.isAuto() && marginEndLength.isAuto() && childWidth < availableWidth)
        || (!marginStartLength.isAuto() && !marginEndLength.isAuto() && containingBlock->style()->textAlign() == WEBKIT_CENTER)) {
        // Other browsers center the margin box for align=center elements so we match them here.
        LayoutUnit marginStartWidth = minimumValueForLength(marginStartLength, containerWidth);
        LayoutUnit marginEndWidth = minimumValueForLength(marginEndLength, containerWidth);
        LayoutUnit centeredMarginBoxStart = max<LayoutUnit>(0, (availableWidth - childWidth - marginStartWidth - marginEndWidth) / 2);
        marginStart = centeredMarginBoxStart + marginStartWidth;
        marginEnd = availableWidth - childWidth - marginStart + marginEndWidth;
        return;
    }

    // Case Two: The object is being pushed to the start of the containing block's available logical width.
    if (marginEndLength.isAuto() && childWidth < availableWidth) {
        marginStart = valueForLength(marginStartLength, containerWidth);
        marginEnd = availableWidth - childWidth - marginStart;
        return;
    }

    // Case Three: The object is being pushed to the end of the containing block's available logical width.
    bool pushToEndFromTextAlign = !marginEndLength.isAuto() && ((!containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_LEFT)
        || (containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_RIGHT));
    if ((marginStartLength.isAuto() && childWidth < availableWidth) || pushToEndFromTextAlign) {
        marginEnd = valueForLength(marginEndLength, containerWidth);
        marginStart = availableWidth - childWidth - marginEnd;
        return;
    }

    // Case Four: Either no auto margins, or our width is >= the container width (css2.1, 10.3.3).  In that case
    // auto margins will just turn into 0.
    marginStart = minimumValueForLength(marginStartLength, containerWidth);
    marginEnd = minimumValueForLength(marginEndLength, containerWidth);
}

static bool shouldFlipBeforeAfterMargins(const RenderStyle* containingBlockStyle, const RenderStyle* childStyle)
{
    ASSERT(containingBlockStyle->isHorizontalWritingMode() != childStyle->isHorizontalWritingMode());
    WritingMode childWritingMode = childStyle->writingMode();
    bool shouldFlip = false;
    switch (containingBlockStyle->writingMode()) {
    case TopToBottomWritingMode:
        shouldFlip = (childWritingMode == RightToLeftWritingMode);
        break;
    case BottomToTopWritingMode:
        shouldFlip = (childWritingMode == RightToLeftWritingMode);
        break;
    case RightToLeftWritingMode:
        shouldFlip = (childWritingMode == BottomToTopWritingMode);
        break;
    case LeftToRightWritingMode:
        shouldFlip = (childWritingMode == BottomToTopWritingMode);
        break;
    }

    if (!containingBlockStyle->isLeftToRightDirection())
        shouldFlip = !shouldFlip;

    return shouldFlip;
}

void RenderBox::updateLogicalHeight()
{
    m_intrinsicContentLogicalHeight = contentLogicalHeight();

    LogicalExtentComputedValues computedValues;
    computeLogicalHeight(logicalHeight(), logicalTop(), computedValues);

    setLogicalHeight(computedValues.m_extent);
    setLogicalTop(computedValues.m_position);
    setMarginBefore(computedValues.m_margins.m_before);
    setMarginAfter(computedValues.m_margins.m_after);
}

void RenderBox::computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
{
    computedValues.m_extent = logicalHeight;
    computedValues.m_position = logicalTop;

    // Cell height is managed by the table and inline non-replaced elements do not support a height property.
    if (isTableCell() || (isInline() && !isReplaced()))
        return;

    Length h;
    if (isOutOfFlowPositioned())
        computePositionedLogicalHeight(computedValues);
    else {
        RenderBlock* cb = containingBlock();
        bool hasPerpendicularContainingBlock = cb->isHorizontalWritingMode() != isHorizontalWritingMode();

        if (!hasPerpendicularContainingBlock) {
            bool shouldFlipBeforeAfter = cb->style()->writingMode() != style()->writingMode();
            computeBlockDirectionMargins(cb,
                shouldFlipBeforeAfter ? computedValues.m_margins.m_after : computedValues.m_margins.m_before,
                shouldFlipBeforeAfter ? computedValues.m_margins.m_before : computedValues.m_margins.m_after);
        }

        // For tables, calculate margins only.
        if (isTable()) {
            if (hasPerpendicularContainingBlock) {
                bool shouldFlipBeforeAfter = shouldFlipBeforeAfterMargins(cb->style(), style());
                computeInlineDirectionMargins(cb, containingBlockLogicalWidthForContent(), computedValues.m_extent,
                    shouldFlipBeforeAfter ? computedValues.m_margins.m_after : computedValues.m_margins.m_before,
                    shouldFlipBeforeAfter ? computedValues.m_margins.m_before : computedValues.m_margins.m_after);
            }
            return;
        }

        // FIXME: Account for block-flow in flexible boxes.
        // https://bugs.webkit.org/show_bug.cgi?id=46418
        bool inHorizontalBox = parent()->isDeprecatedFlexibleBox() && parent()->style()->boxOrient() == HORIZONTAL;
        bool stretching = parent()->style()->boxAlign() == BSTRETCH;
        bool treatAsReplaced = shouldComputeSizeAsReplaced() && (!inHorizontalBox || !stretching);
        bool checkMinMaxHeight = false;

        // The parent box is flexing us, so it has increased or decreased our height.  We have to
        // grab our cached flexible height.
        // FIXME: Account for block-flow in flexible boxes.
        // https://bugs.webkit.org/show_bug.cgi?id=46418
        if (hasOverrideHeight() && parent()->isFlexibleBoxIncludingDeprecated())
            h = Length(overrideLogicalContentHeight(), Fixed);
        else if (treatAsReplaced)
            h = Length(computeReplacedLogicalHeight(), Fixed);
        else {
            h = style()->logicalHeight();
            checkMinMaxHeight = true;
        }

        // Block children of horizontal flexible boxes fill the height of the box.
        // FIXME: Account for block-flow in flexible boxes.
        // https://bugs.webkit.org/show_bug.cgi?id=46418
        if (h.isAuto() && inHorizontalBox && toRenderDeprecatedFlexibleBox(parent())->isStretchingChildren()) {
            h = Length(parentBox()->contentLogicalHeight() - marginBefore() - marginAfter() - borderAndPaddingLogicalHeight(), Fixed);
            checkMinMaxHeight = false;
        }

        LayoutUnit heightResult;
        if (checkMinMaxHeight) {
            heightResult = computeLogicalHeightUsing(style()->logicalHeight(), computedValues.m_extent - borderAndPaddingLogicalHeight());
            if (heightResult == -1)
                heightResult = computedValues.m_extent;
            heightResult = constrainLogicalHeightByMinMax(heightResult, computedValues.m_extent - borderAndPaddingLogicalHeight());
        } else {
            // The only times we don't check min/max height are when a fixed length has
            // been given as an override.  Just use that.  The value has already been adjusted
            // for box-sizing.
            ASSERT(h.isFixed());
            heightResult = h.value() + borderAndPaddingLogicalHeight();
        }

        computedValues.m_extent = heightResult;

        if (hasPerpendicularContainingBlock) {
            bool shouldFlipBeforeAfter = shouldFlipBeforeAfterMargins(cb->style(), style());
            computeInlineDirectionMargins(cb, containingBlockLogicalWidthForContent(), heightResult,
                shouldFlipBeforeAfter ? computedValues.m_margins.m_after : computedValues.m_margins.m_before,
                shouldFlipBeforeAfter ? computedValues.m_margins.m_before : computedValues.m_margins.m_after);
        }
    }

    // WinIE quirk: The <html> block always fills the entire canvas in quirks mode.  The <body> always fills the
    // <html> block in quirks mode.  Only apply this quirk if the block is normal flow and no height
    // is specified. When we're printing, we also need this quirk if the body or root has a percentage
    // height since we don't set a height in RenderView when we're printing. So without this quirk, the
    // height has nothing to be a percentage of, and it ends up being 0. That is bad.
    bool paginatedContentNeedsBaseHeight = document().printing() && h.isPercent()
        && (isRoot() || (isBody() && document().documentElement()->renderer()->style()->logicalHeight().isPercent())) && !isInline();
    if (stretchesToViewport() || paginatedContentNeedsBaseHeight) {
        LayoutUnit margins = collapsedMarginBefore() + collapsedMarginAfter();
        LayoutUnit visibleHeight = viewLogicalHeightForPercentages();
        if (isRoot())
            computedValues.m_extent = max(computedValues.m_extent, visibleHeight - margins);
        else {
            LayoutUnit marginsBordersPadding = margins + parentBox()->marginBefore() + parentBox()->marginAfter() + parentBox()->borderAndPaddingLogicalHeight();
            computedValues.m_extent = max(computedValues.m_extent, visibleHeight - marginsBordersPadding);
        }
    }
}

LayoutUnit RenderBox::viewLogicalHeightForPercentages() const
{
    if (document().printing())
        return static_cast<LayoutUnit>(view()->pageLogicalHeight());
    return view()->viewLogicalHeight();
}

LayoutUnit RenderBox::computeLogicalHeightUsing(const Length& height, LayoutUnit intrinsicContentHeight) const
{
    LayoutUnit logicalHeight = computeContentAndScrollbarLogicalHeightUsing(height, intrinsicContentHeight);
    if (logicalHeight != -1)
        logicalHeight = adjustBorderBoxLogicalHeightForBoxSizing(logicalHeight);
    return logicalHeight;
}

LayoutUnit RenderBox::computeContentLogicalHeight(const Length& height, LayoutUnit intrinsicContentHeight) const
{
    LayoutUnit heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(height, intrinsicContentHeight);
    if (heightIncludingScrollbar == -1)
        return -1;
    return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());
}

LayoutUnit RenderBox::computeIntrinsicLogicalContentHeightUsing(Length logicalHeightLength, LayoutUnit intrinsicContentHeight, LayoutUnit borderAndPadding) const
{
    // FIXME(cbiesinger): The css-sizing spec is considering changing what min-content/max-content should resolve to.
    // If that happens, this code will have to change.
    if (logicalHeightLength.isMinContent() || logicalHeightLength.isMaxContent() || logicalHeightLength.isFitContent()) {
        if (isReplaced())
            return intrinsicSize().height();
        if (m_intrinsicContentLogicalHeight != -1)
            return m_intrinsicContentLogicalHeight;
        return intrinsicContentHeight;
    }
    if (logicalHeightLength.isFillAvailable())
        return containingBlock()->availableLogicalHeight(ExcludeMarginBorderPadding) - borderAndPadding;
    ASSERT_NOT_REACHED();
    return 0;
}

LayoutUnit RenderBox::computeContentAndScrollbarLogicalHeightUsing(const Length& height, LayoutUnit intrinsicContentHeight) const
{
    // FIXME(cbiesinger): The css-sizing spec is considering changing what min-content/max-content should resolve to.
    // If that happens, this code will have to change.
    if (height.isIntrinsic()) {
        if (intrinsicContentHeight == -1)
            return -1; // Intrinsic height isn't available.
        return computeIntrinsicLogicalContentHeightUsing(height, intrinsicContentHeight, borderAndPaddingLogicalHeight());
    }
    if (height.isFixed())
        return height.value();
    if (height.isPercent())
        return computePercentageLogicalHeight(height);
    return -1;
}

bool RenderBox::skipContainingBlockForPercentHeightCalculation(const RenderBox* containingBlock) const
{
    // Flow threads for multicol or paged overflow should be skipped. They are invisible to the DOM,
    // and percent heights of children should be resolved against the multicol or paged container.
    if (containingBlock->isRenderFlowThread())
        return true;

    // For quirks mode and anonymous blocks, we skip auto-height containingBlocks when computing percentages.
    // For standards mode, we treat the percentage as auto if it has an auto-height containing block.
    if (!document().inQuirksMode() && !containingBlock->isAnonymousBlock())
        return false;
    return !containingBlock->isTableCell() && !containingBlock->isOutOfFlowPositioned() && containingBlock->style()->logicalHeight().isAuto() && isHorizontalWritingMode() == containingBlock->isHorizontalWritingMode();
}

LayoutUnit RenderBox::computePercentageLogicalHeight(const Length& height) const
{
    LayoutUnit availableHeight = -1;

    bool skippedAutoHeightContainingBlock = false;
    RenderBlock* cb = containingBlock();
    const RenderBox* containingBlockChild = this;
    LayoutUnit rootMarginBorderPaddingHeight = 0;
    while (!cb->isRenderView() && skipContainingBlockForPercentHeightCalculation(cb)) {
        if (cb->isBody() || cb->isRoot())
            rootMarginBorderPaddingHeight += cb->marginBefore() + cb->marginAfter() + cb->borderAndPaddingLogicalHeight();
        skippedAutoHeightContainingBlock = true;
        containingBlockChild = cb;
        cb = cb->containingBlock();
    }
    cb->addPercentHeightDescendant(const_cast<RenderBox*>(this));

    RenderStyle* cbstyle = cb->style();

    // A positioned element that specified both top/bottom or that specifies height should be treated as though it has a height
    // explicitly specified that can be used for any percentage computations.
    bool isOutOfFlowPositionedWithSpecifiedHeight = cb->isOutOfFlowPositioned() && (!cbstyle->logicalHeight().isAuto() || (!cbstyle->logicalTop().isAuto() && !cbstyle->logicalBottom().isAuto()));

    bool includeBorderPadding = isTable();

    if (isHorizontalWritingMode() != cb->isHorizontalWritingMode())
        availableHeight = containingBlockChild->containingBlockLogicalWidthForContent();
    else if (hasOverrideContainingBlockLogicalHeight())
        availableHeight = overrideContainingBlockContentLogicalHeight();
    else if (cb->isTableCell()) {
        if (!skippedAutoHeightContainingBlock) {
            // Table cells violate what the CSS spec says to do with heights. Basically we
            // don't care if the cell specified a height or not. We just always make ourselves
            // be a percentage of the cell's current content height.
            if (!cb->hasOverrideHeight()) {
                // Normally we would let the cell size intrinsically, but scrolling overflow has to be
                // treated differently, since WinIE lets scrolled overflow regions shrink as needed.
                // While we can't get all cases right, we can at least detect when the cell has a specified
                // height or when the table has a specified height. In these cases we want to initially have
                // no size and allow the flexing of the table or the cell to its specified height to cause us
                // to grow to fill the space. This could end up being wrong in some cases, but it is
                // preferable to the alternative (sizing intrinsically and making the row end up too big).
                RenderTableCell* cell = toRenderTableCell(cb);
                if (scrollsOverflowY() && (!cell->style()->logicalHeight().isAuto() || !cell->table()->style()->logicalHeight().isAuto()))
                    return 0;
                return -1;
            }
            availableHeight = cb->overrideLogicalContentHeight();
            includeBorderPadding = true;
        }
    } else if (cbstyle->logicalHeight().isFixed()) {
        LayoutUnit contentBoxHeight = cb->adjustContentBoxLogicalHeightForBoxSizing(cbstyle->logicalHeight().value());
        availableHeight = max<LayoutUnit>(0, cb->constrainContentBoxLogicalHeightByMinMax(contentBoxHeight - cb->scrollbarLogicalHeight(), -1));
    } else if (cbstyle->logicalHeight().isPercent() && !isOutOfFlowPositionedWithSpecifiedHeight) {
        // We need to recur and compute the percentage height for our containing block.
        LayoutUnit heightWithScrollbar = cb->computePercentageLogicalHeight(cbstyle->logicalHeight());
        if (heightWithScrollbar != -1) {
            LayoutUnit contentBoxHeightWithScrollbar = cb->adjustContentBoxLogicalHeightForBoxSizing(heightWithScrollbar);
            // We need to adjust for min/max height because this method does not
            // handle the min/max of the current block, its caller does. So the
            // return value from the recursive call will not have been adjusted
            // yet.
            LayoutUnit contentBoxHeight = cb->constrainContentBoxLogicalHeightByMinMax(contentBoxHeightWithScrollbar - cb->scrollbarLogicalHeight(), -1);
            availableHeight = max<LayoutUnit>(0, contentBoxHeight);
        }
    } else if (isOutOfFlowPositionedWithSpecifiedHeight) {
        // Don't allow this to affect the block' height() member variable, since this
        // can get called while the block is still laying out its kids.
        LogicalExtentComputedValues computedValues;
        cb->computeLogicalHeight(cb->logicalHeight(), 0, computedValues);
        availableHeight = computedValues.m_extent - cb->borderAndPaddingLogicalHeight() - cb->scrollbarLogicalHeight();
    } else if (cb->isRenderView())
        availableHeight = viewLogicalHeightForPercentages();

    if (availableHeight == -1)
        return availableHeight;

    availableHeight -= rootMarginBorderPaddingHeight;

    LayoutUnit result = valueForLength(height, availableHeight);
    if (includeBorderPadding) {
        // FIXME: Table cells should default to box-sizing: border-box so we can avoid this hack.
        // It is necessary to use the border-box to match WinIE's broken
        // box model. This is essential for sizing inside
        // table cells using percentage heights.
        result -= borderAndPaddingLogicalHeight();
        return max<LayoutUnit>(0, result);
    }
    return result;
}

LayoutUnit RenderBox::computeReplacedLogicalWidth(ShouldComputePreferred shouldComputePreferred) const
{
    return computeReplacedLogicalWidthRespectingMinMaxWidth(computeReplacedLogicalWidthUsing(style()->logicalWidth()), shouldComputePreferred);
}

LayoutUnit RenderBox::computeReplacedLogicalWidthRespectingMinMaxWidth(LayoutUnit logicalWidth, ShouldComputePreferred shouldComputePreferred) const
{
    LayoutUnit minLogicalWidth = (shouldComputePreferred == ComputePreferred && style()->logicalMinWidth().isPercent()) || style()->logicalMinWidth().isUndefined() ? logicalWidth : computeReplacedLogicalWidthUsing(style()->logicalMinWidth());
    LayoutUnit maxLogicalWidth = (shouldComputePreferred == ComputePreferred && style()->logicalMaxWidth().isPercent()) || style()->logicalMaxWidth().isUndefined() ? logicalWidth : computeReplacedLogicalWidthUsing(style()->logicalMaxWidth());
    return max(minLogicalWidth, min(logicalWidth, maxLogicalWidth));
}

LayoutUnit RenderBox::computeReplacedLogicalWidthUsing(Length logicalWidth) const
{
    switch (logicalWidth.type()) {
        case Fixed:
            return adjustContentBoxLogicalWidthForBoxSizing(logicalWidth.value());
        case MinContent:
        case MaxContent: {
            // MinContent/MaxContent don't need the availableLogicalWidth argument.
            LayoutUnit availableLogicalWidth = 0;
            return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
        }
        case FitContent:
        case FillAvailable:
        case Percent:
        case Calculated: {
            // FIXME: containingBlockLogicalWidthForContent() is wrong if the replaced element's block-flow is perpendicular to the
            // containing block's block-flow.
            // https://bugs.webkit.org/show_bug.cgi?id=46496
            const LayoutUnit cw = isOutOfFlowPositioned() ? containingBlockLogicalWidthForPositioned(toRenderBoxModelObject(container())) : containingBlockLogicalWidthForContent();
            Length containerLogicalWidth = containingBlock()->style()->logicalWidth();
            // FIXME: Handle cases when containing block width is calculated or viewport percent.
            // https://bugs.webkit.org/show_bug.cgi?id=91071
            if (logicalWidth.isIntrinsic())
                return computeIntrinsicLogicalWidthUsing(logicalWidth, cw, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
            if (cw > 0 || (!cw && (containerLogicalWidth.isFixed() || containerLogicalWidth.isPercent())))
                return adjustContentBoxLogicalWidthForBoxSizing(minimumValueForLength(logicalWidth, cw));
        }
        // fall through
        case Intrinsic:
        case MinIntrinsic:
        case Auto:
        case Undefined:
            return intrinsicLogicalWidth();
        case ExtendToZoom:
        case DeviceWidth:
        case DeviceHeight:
            break;
    }

    ASSERT_NOT_REACHED();
    return 0;
}

LayoutUnit RenderBox::computeReplacedLogicalHeight() const
{
    return computeReplacedLogicalHeightRespectingMinMaxHeight(computeReplacedLogicalHeightUsing(style()->logicalHeight()));
}

LayoutUnit RenderBox::computeReplacedLogicalHeightRespectingMinMaxHeight(LayoutUnit logicalHeight) const
{
    LayoutUnit minLogicalHeight = computeReplacedLogicalHeightUsing(style()->logicalMinHeight());
    LayoutUnit maxLogicalHeight = style()->logicalMaxHeight().isUndefined() ? logicalHeight : computeReplacedLogicalHeightUsing(style()->logicalMaxHeight());
    return max(minLogicalHeight, min(logicalHeight, maxLogicalHeight));
}

LayoutUnit RenderBox::computeReplacedLogicalHeightUsing(Length logicalHeight) const
{
    switch (logicalHeight.type()) {
        case Fixed:
            return adjustContentBoxLogicalHeightForBoxSizing(logicalHeight.value());
        case Percent:
        case Calculated:
        {
            RenderObject* cb = isOutOfFlowPositioned() ? container() : containingBlock();
            while (cb->isAnonymous())
                cb = cb->containingBlock();
            if (cb->isRenderBlock())
                toRenderBlock(cb)->addPercentHeightDescendant(const_cast<RenderBox*>(this));

            // FIXME: This calculation is not patched for block-flow yet.
            // https://bugs.webkit.org/show_bug.cgi?id=46500
            if (cb->isOutOfFlowPositioned() && cb->style()->height().isAuto() && !(cb->style()->top().isAuto() || cb->style()->bottom().isAuto())) {
                ASSERT_WITH_SECURITY_IMPLICATION(cb->isRenderBlock());
                RenderBlock* block = toRenderBlock(cb);
                LogicalExtentComputedValues computedValues;
                block->computeLogicalHeight(block->logicalHeight(), 0, computedValues);
                LayoutUnit newContentHeight = computedValues.m_extent - block->borderAndPaddingLogicalHeight() - block->scrollbarLogicalHeight();
                LayoutUnit newHeight = block->adjustContentBoxLogicalHeightForBoxSizing(newContentHeight);
                return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeight, newHeight));
            }

            // FIXME: availableLogicalHeight() is wrong if the replaced element's block-flow is perpendicular to the
            // containing block's block-flow.
            // https://bugs.webkit.org/show_bug.cgi?id=46496
            LayoutUnit availableHeight;
            if (isOutOfFlowPositioned())
                availableHeight = containingBlockLogicalHeightForPositioned(toRenderBoxModelObject(cb));
            else {
                availableHeight = containingBlockLogicalHeightForContent(IncludeMarginBorderPadding);
                // It is necessary to use the border-box to match WinIE's broken
                // box model.  This is essential for sizing inside
                // table cells using percentage heights.
                // FIXME: This needs to be made block-flow-aware.  If the cell and image are perpendicular block-flows, this isn't right.
                // https://bugs.webkit.org/show_bug.cgi?id=46997
                while (cb && !cb->isRenderView() && (cb->style()->logicalHeight().isAuto() || cb->style()->logicalHeight().isPercent())) {
                    if (cb->isTableCell()) {
                        // Don't let table cells squeeze percent-height replaced elements
                        // <http://bugs.webkit.org/show_bug.cgi?id=15359>
                        availableHeight = max(availableHeight, intrinsicLogicalHeight());
                        return valueForLength(logicalHeight, availableHeight - borderAndPaddingLogicalHeight());
                    }
                    toRenderBlock(cb)->addPercentHeightDescendant(const_cast<RenderBox*>(this));
                    cb = cb->containingBlock();
                }
            }
            return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeight, availableHeight));
        }
        case MinContent:
        case MaxContent:
        case FitContent:
        case FillAvailable:
            return adjustContentBoxLogicalHeightForBoxSizing(computeIntrinsicLogicalContentHeightUsing(logicalHeight, intrinsicLogicalHeight(), borderAndPaddingHeight()));
        default:
            return intrinsicLogicalHeight();
    }
}

LayoutUnit RenderBox::availableLogicalHeight(AvailableLogicalHeightType heightType) const
{
    return constrainLogicalHeightByMinMax(availableLogicalHeightUsing(style()->logicalHeight(), heightType), -1);
}

LayoutUnit RenderBox::availableLogicalHeightUsing(const Length& h, AvailableLogicalHeightType heightType) const
{
    if (isRenderView())
        return isHorizontalWritingMode() ? toRenderView(this)->frameView()->visibleHeight() : toRenderView(this)->frameView()->visibleWidth();

    // We need to stop here, since we don't want to increase the height of the table
    // artificially.  We're going to rely on this cell getting expanded to some new
    // height, and then when we lay out again we'll use the calculation below.
    if (isTableCell() && (h.isAuto() || h.isPercent())) {
        if (hasOverrideHeight())
            return overrideLogicalContentHeight();
        return logicalHeight() - borderAndPaddingLogicalHeight();
    }

    if (h.isPercent() && isOutOfFlowPositioned() && !isRenderFlowThread()) {
        // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
        LayoutUnit availableHeight = containingBlockLogicalHeightForPositioned(containingBlock());
        return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(h, availableHeight));
    }

    LayoutUnit heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(h, -1);
    if (heightIncludingScrollbar != -1)
        return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());

    // FIXME: Check logicalTop/logicalBottom here to correctly handle vertical writing-mode.
    // https://bugs.webkit.org/show_bug.cgi?id=46500
    if (isRenderBlock() && isOutOfFlowPositioned() && style()->height().isAuto() && !(style()->top().isAuto() || style()->bottom().isAuto())) {
        RenderBlock* block = const_cast<RenderBlock*>(toRenderBlock(this));
        LogicalExtentComputedValues computedValues;
        block->computeLogicalHeight(block->logicalHeight(), 0, computedValues);
        LayoutUnit newContentHeight = computedValues.m_extent - block->borderAndPaddingLogicalHeight() - block->scrollbarLogicalHeight();
        return adjustContentBoxLogicalHeightForBoxSizing(newContentHeight);
    }

    // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
    LayoutUnit availableHeight = containingBlockLogicalHeightForContent(heightType);
    if (heightType == ExcludeMarginBorderPadding) {
        // FIXME: Margin collapsing hasn't happened yet, so this incorrectly removes collapsed margins.
        availableHeight -= marginBefore() + marginAfter() + borderAndPaddingLogicalHeight();
    }
    return availableHeight;
}

void RenderBox::computeBlockDirectionMargins(const RenderBlock* containingBlock, LayoutUnit& marginBefore, LayoutUnit& marginAfter) const
{
    if (isTableCell()) {
        // FIXME: Not right if we allow cells to have different directionality than the table.  If we do allow this, though,
        // we may just do it with an extra anonymous block inside the cell.
        marginBefore = 0;
        marginAfter = 0;
        return;
    }

    // Margins are calculated with respect to the logical width of
    // the containing block (8.3)
    LayoutUnit cw = containingBlockLogicalWidthForContent();
    RenderStyle* containingBlockStyle = containingBlock->style();
    marginBefore = minimumValueForLength(style()->marginBeforeUsing(containingBlockStyle), cw);
    marginAfter = minimumValueForLength(style()->marginAfterUsing(containingBlockStyle), cw);
}

void RenderBox::computeAndSetBlockDirectionMargins(const RenderBlock* containingBlock)
{
    LayoutUnit marginBefore;
    LayoutUnit marginAfter;
    computeBlockDirectionMargins(containingBlock, marginBefore, marginAfter);
    containingBlock->setMarginBeforeForChild(this, marginBefore);
    containingBlock->setMarginAfterForChild(this, marginAfter);
}

LayoutUnit RenderBox::containingBlockLogicalWidthForPositioned(const RenderBoxModelObject* containingBlock, bool checkForPerpendicularWritingMode) const
{
    if (checkForPerpendicularWritingMode && containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
        return containingBlockLogicalHeightForPositioned(containingBlock, false);

    // Use viewport as container for top-level fixed-position elements.
    if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
        const RenderView* view = toRenderView(containingBlock);
        if (FrameView* frameView = view->frameView()) {
            LayoutRect viewportRect = frameView->viewportConstrainedVisibleContentRect();
            return containingBlock->isHorizontalWritingMode() ? viewportRect.width() : viewportRect.height();
        }
    }

    if (containingBlock->isBox())
        return toRenderBox(containingBlock)->clientLogicalWidth();

    ASSERT(containingBlock->isRenderInline() && containingBlock->isInFlowPositioned());

    const RenderInline* flow = toRenderInline(containingBlock);
    InlineFlowBox* first = flow->firstLineBox();
    InlineFlowBox* last = flow->lastLineBox();

    // If the containing block is empty, return a width of 0.
    if (!first || !last)
        return 0;

    LayoutUnit fromLeft;
    LayoutUnit fromRight;
    if (containingBlock->style()->isLeftToRightDirection()) {
        fromLeft = first->logicalLeft() + first->borderLogicalLeft();
        fromRight = last->logicalLeft() + last->logicalWidth() - last->borderLogicalRight();
    } else {
        fromRight = first->logicalLeft() + first->logicalWidth() - first->borderLogicalRight();
        fromLeft = last->logicalLeft() + last->borderLogicalLeft();
    }

    return max<LayoutUnit>(0, fromRight - fromLeft);
}

LayoutUnit RenderBox::containingBlockLogicalHeightForPositioned(const RenderBoxModelObject* containingBlock, bool checkForPerpendicularWritingMode) const
{
    if (checkForPerpendicularWritingMode && containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
        return containingBlockLogicalWidthForPositioned(containingBlock, false);

    // Use viewport as container for top-level fixed-position elements.
    if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
        const RenderView* view = toRenderView(containingBlock);
        if (FrameView* frameView = view->frameView()) {
            LayoutRect viewportRect = frameView->viewportConstrainedVisibleContentRect();
            return containingBlock->isHorizontalWritingMode() ? viewportRect.height() : viewportRect.width();
        }
    }

    if (containingBlock->isBox()) {
        const RenderBlock* cb = containingBlock->isRenderBlock() ?
            toRenderBlock(containingBlock) : containingBlock->containingBlock();
        return cb->clientLogicalHeight();
    }

    ASSERT(containingBlock->isRenderInline() && containingBlock->isInFlowPositioned());

    const RenderInline* flow = toRenderInline(containingBlock);
    InlineFlowBox* first = flow->firstLineBox();
    InlineFlowBox* last = flow->lastLineBox();

    // If the containing block is empty, return a height of 0.
    if (!first || !last)
        return 0;

    LayoutUnit heightResult;
    LayoutRect boundingBox = flow->linesBoundingBox();
    if (containingBlock->isHorizontalWritingMode())
        heightResult = boundingBox.height();
    else
        heightResult = boundingBox.width();
    heightResult -= (containingBlock->borderBefore() + containingBlock->borderAfter());
    return heightResult;
}

static void computeInlineStaticDistance(Length& logicalLeft, Length& logicalRight, const RenderBox* child, const RenderBoxModelObject* containerBlock, LayoutUnit containerLogicalWidth)
{
    if (!logicalLeft.isAuto() || !logicalRight.isAuto())
        return;

    // FIXME: The static distance computation has not been patched for mixed writing modes yet.
    if (child->parent()->style()->direction() == LTR) {
        LayoutUnit staticPosition = child->layer()->staticInlinePosition() - containerBlock->borderLogicalLeft();
        for (RenderObject* curr = child->parent(); curr && curr != containerBlock; curr = curr->container()) {
            if (curr->isBox()) {
                staticPosition += toRenderBox(curr)->logicalLeft();
                if (toRenderBox(curr)->isRelPositioned())
                    staticPosition += toRenderBox(curr)->relativePositionOffset().width();
            } else if (curr->isInline()) {
                if (curr->isRelPositioned()) {
                    if (!curr->style()->logicalLeft().isAuto())
                        staticPosition += curr->style()->logicalLeft().value();
                    else
                        staticPosition -= curr->style()->logicalRight().value();
                }
            }
        }
        logicalLeft.setValue(Fixed, staticPosition);
    } else {
        RenderBox* enclosingBox = child->parent()->enclosingBox();
        LayoutUnit staticPosition = child->layer()->staticInlinePosition() + containerLogicalWidth + containerBlock->borderLogicalLeft();
        for (RenderObject* curr = child->parent(); curr; curr = curr->container()) {
            if (curr->isBox()) {
                if (curr != containerBlock) {
                    staticPosition -= toRenderBox(curr)->logicalLeft();
                    if (toRenderBox(curr)->isRelPositioned())
                        staticPosition -= toRenderBox(curr)->relativePositionOffset().width();
                }
                if (curr == enclosingBox)
                    staticPosition -= enclosingBox->logicalWidth();
            } else if (curr->isInline()) {
                if (curr->isRelPositioned()) {
                    if (!curr->style()->logicalLeft().isAuto())
                        staticPosition -= curr->style()->logicalLeft().value();
                    else
                        staticPosition += curr->style()->logicalRight().value();
                }
            }
            if (curr == containerBlock)
                break;
        }
        logicalRight.setValue(Fixed, staticPosition);
    }
}

void RenderBox::computePositionedLogicalWidth(LogicalExtentComputedValues& computedValues) const
{
    if (isReplaced()) {
        computePositionedLogicalWidthReplaced(computedValues);
        return;
    }

    // QUESTIONS
    // FIXME 1: Should we still deal with these the cases of 'left' or 'right' having
    // the type 'static' in determining whether to calculate the static distance?
    // NOTE: 'static' is not a legal value for 'left' or 'right' as of CSS 2.1.

    // FIXME 2: Can perhaps optimize out cases when max-width/min-width are greater
    // than or less than the computed width().  Be careful of box-sizing and
    // percentage issues.

    // The following is based off of the W3C Working Draft from April 11, 2006 of
    // CSS 2.1: Section 10.3.7 "Absolutely positioned, non-replaced elements"
    // <http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width>
    // (block-style-comments in this function and in computePositionedLogicalWidthUsing()
    // correspond to text from the spec)


    // We don't use containingBlock(), since we may be positioned by an enclosing
    // relative positioned inline.
    const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());

    const LayoutUnit containerLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock);

    // Use the container block's direction except when calculating the static distance
    // This conforms with the reference results for abspos-replaced-width-margin-000.htm
    // of the CSS 2.1 test suite
    TextDirection containerDirection = containerBlock->style()->direction();

    bool isHorizontal = isHorizontalWritingMode();
    const LayoutUnit bordersPlusPadding = borderAndPaddingLogicalWidth();
    const Length marginLogicalLeft = isHorizontal ? style()->marginLeft() : style()->marginTop();
    const Length marginLogicalRight = isHorizontal ? style()->marginRight() : style()->marginBottom();

    Length logicalLeftLength = style()->logicalLeft();
    Length logicalRightLength = style()->logicalRight();

    /*---------------------------------------------------------------------------*\
     * For the purposes of this section and the next, the term "static position"
     * (of an element) refers, roughly, to the position an element would have had
     * in the normal flow. More precisely:
     *
     * * The static position for 'left' is the distance from the left edge of the
     *   containing block to the left margin edge of a hypothetical box that would
     *   have been the first box of the element if its 'position' property had
     *   been 'static' and 'float' had been 'none'. The value is negative if the
     *   hypothetical box is to the left of the containing block.
     * * The static position for 'right' is the distance from the right edge of the
     *   containing block to the right margin edge of the same hypothetical box as
     *   above. The value is positive if the hypothetical box is to the left of the
     *   containing block's edge.
     *
     * But rather than actually calculating the dimensions of that hypothetical box,
     * user agents are free to make a guess at its probable position.
     *
     * For the purposes of calculating the static position, the containing block of
     * fixed positioned elements is the initial containing block instead of the
     * viewport, and all scrollable boxes should be assumed to be scrolled to their
     * origin.
    \*---------------------------------------------------------------------------*/

    // see FIXME 1
    // Calculate the static distance if needed.
    computeInlineStaticDistance(logicalLeftLength, logicalRightLength, this, containerBlock, containerLogicalWidth);

    // Calculate constraint equation values for 'width' case.
    computePositionedLogicalWidthUsing(style()->logicalWidth(), containerBlock, containerDirection,
                                       containerLogicalWidth, bordersPlusPadding,
                                       logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
                                       computedValues);

    // Calculate constraint equation values for 'max-width' case.
    if (!style()->logicalMaxWidth().isUndefined()) {
        LogicalExtentComputedValues maxValues;

        computePositionedLogicalWidthUsing(style()->logicalMaxWidth(), containerBlock, containerDirection,
                                           containerLogicalWidth, bordersPlusPadding,
                                           logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
                                           maxValues);

        if (computedValues.m_extent > maxValues.m_extent) {
            computedValues.m_extent = maxValues.m_extent;
            computedValues.m_position = maxValues.m_position;
            computedValues.m_margins.m_start = maxValues.m_margins.m_start;
            computedValues.m_margins.m_end = maxValues.m_margins.m_end;
        }
    }

    // Calculate constraint equation values for 'min-width' case.
    if (!style()->logicalMinWidth().isZero() || style()->logicalMinWidth().isIntrinsic()) {
        LogicalExtentComputedValues minValues;

        computePositionedLogicalWidthUsing(style()->logicalMinWidth(), containerBlock, containerDirection,
                                           containerLogicalWidth, bordersPlusPadding,
                                           logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
                                           minValues);

        if (computedValues.m_extent < minValues.m_extent) {
            computedValues.m_extent = minValues.m_extent;
            computedValues.m_position = minValues.m_position;
            computedValues.m_margins.m_start = minValues.m_margins.m_start;
            computedValues.m_margins.m_end = minValues.m_margins.m_end;
        }
    }

    computedValues.m_extent += bordersPlusPadding;
}

static void computeLogicalLeftPositionedOffset(LayoutUnit& logicalLeftPos, const RenderBox* child, LayoutUnit logicalWidthValue, const RenderBoxModelObject* containerBlock, LayoutUnit containerLogicalWidth)
{
    // Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space. If the containing block is flipped
    // along this axis, then we need to flip the coordinate.  This can only happen if the containing block is both a flipped mode and perpendicular to us.
    if (containerBlock->isHorizontalWritingMode() != child->isHorizontalWritingMode() && containerBlock->style()->isFlippedBlocksWritingMode()) {
        logicalLeftPos = containerLogicalWidth - logicalWidthValue - logicalLeftPos;
        logicalLeftPos += (child->isHorizontalWritingMode() ? containerBlock->borderRight() : containerBlock->borderBottom());
    } else {
        logicalLeftPos += (child->isHorizontalWritingMode() ? containerBlock->borderLeft() : containerBlock->borderTop());
    }
}

void RenderBox::shrinkToFitWidth(const LayoutUnit availableSpace, const LayoutUnit logicalLeftValue, const LayoutUnit bordersPlusPadding, LogicalExtentComputedValues& computedValues) const
{
    // FIXME: would it be better to have shrink-to-fit in one step?
    LayoutUnit preferredWidth = maxPreferredLogicalWidth() - bordersPlusPadding;
    LayoutUnit preferredMinWidth = minPreferredLogicalWidth() - bordersPlusPadding;
    LayoutUnit availableWidth = availableSpace - logicalLeftValue;
    computedValues.m_extent = min(max(preferredMinWidth, availableWidth), preferredWidth);
}

void RenderBox::computePositionedLogicalWidthUsing(Length logicalWidth, const RenderBoxModelObject* containerBlock, TextDirection containerDirection,
                                                   LayoutUnit containerLogicalWidth, LayoutUnit bordersPlusPadding,
                                                   Length logicalLeft, Length logicalRight, Length marginLogicalLeft, Length marginLogicalRight,
                                                   LogicalExtentComputedValues& computedValues) const
{
    if (logicalWidth.isIntrinsic())
        logicalWidth = Length(computeIntrinsicLogicalWidthUsing(logicalWidth, containerLogicalWidth, bordersPlusPadding) - bordersPlusPadding, Fixed);

    // 'left' and 'right' cannot both be 'auto' because one would of been
    // converted to the static position already
    ASSERT(!(logicalLeft.isAuto() && logicalRight.isAuto()));

    LayoutUnit logicalLeftValue = 0;

    const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);

    bool logicalWidthIsAuto = logicalWidth.isIntrinsicOrAuto();
    bool logicalLeftIsAuto = logicalLeft.isAuto();
    bool logicalRightIsAuto = logicalRight.isAuto();
    LayoutUnit& marginLogicalLeftValue = style()->isLeftToRightDirection() ? computedValues.m_margins.m_start : computedValues.m_margins.m_end;
    LayoutUnit& marginLogicalRightValue = style()->isLeftToRightDirection() ? computedValues.m_margins.m_end : computedValues.m_margins.m_start;
    if (!logicalLeftIsAuto && !logicalWidthIsAuto && !logicalRightIsAuto) {
        /*-----------------------------------------------------------------------*\
         * If none of the three is 'auto': If both 'margin-left' and 'margin-
         * right' are 'auto', solve the equation under the extra constraint that
         * the two margins get equal values, unless this would make them negative,
         * in which case when direction of the containing block is 'ltr' ('rtl'),
         * set 'margin-left' ('margin-right') to zero and solve for 'margin-right'
         * ('margin-left'). If one of 'margin-left' or 'margin-right' is 'auto',
         * solve the equation for that value. If the values are over-constrained,
         * ignore the value for 'left' (in case the 'direction' property of the
         * containing block is 'rtl') or 'right' (in case 'direction' is 'ltr')
         * and solve for that value.
        \*-----------------------------------------------------------------------*/
        // NOTE:  It is not necessary to solve for 'right' in the over constrained
        // case because the value is not used for any further calculations.

        logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
        computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));

        const LayoutUnit availableSpace = containerLogicalWidth - (logicalLeftValue + computedValues.m_extent + valueForLength(logicalRight, containerLogicalWidth) + bordersPlusPadding);

        // Margins are now the only unknown
        if (marginLogicalLeft.isAuto() && marginLogicalRight.isAuto()) {
            // Both margins auto, solve for equality
            if (availableSpace >= 0) {
                marginLogicalLeftValue = availableSpace / 2; // split the difference
                marginLogicalRightValue = availableSpace - marginLogicalLeftValue; // account for odd valued differences
            } else {
                // Use the containing block's direction rather than the parent block's
                // per CSS 2.1 reference test abspos-non-replaced-width-margin-000.
                if (containerDirection == LTR) {
                    marginLogicalLeftValue = 0;
                    marginLogicalRightValue = availableSpace; // will be negative
                } else {
                    marginLogicalLeftValue = availableSpace; // will be negative
                    marginLogicalRightValue = 0;
                }
            }
        } else if (marginLogicalLeft.isAuto()) {
            // Solve for left margin
            marginLogicalRightValue = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
            marginLogicalLeftValue = availableSpace - marginLogicalRightValue;
        } else if (marginLogicalRight.isAuto()) {
            // Solve for right margin
            marginLogicalLeftValue = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
            marginLogicalRightValue = availableSpace - marginLogicalLeftValue;
        } else {
            // Over-constrained, solve for left if direction is RTL
            marginLogicalLeftValue = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
            marginLogicalRightValue = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);

            // Use the containing block's direction rather than the parent block's
            // per CSS 2.1 reference test abspos-non-replaced-width-margin-000.
            if (containerDirection == RTL)
                logicalLeftValue = (availableSpace + logicalLeftValue) - marginLogicalLeftValue - marginLogicalRightValue;
        }
    } else {
        /*--------------------------------------------------------------------*\
         * Otherwise, set 'auto' values for 'margin-left' and 'margin-right'
         * to 0, and pick the one of the following six rules that applies.
         *
         * 1. 'left' and 'width' are 'auto' and 'right' is not 'auto', then the
         *    width is shrink-to-fit. Then solve for 'left'
         *
         *              OMIT RULE 2 AS IT SHOULD NEVER BE HIT
         * ------------------------------------------------------------------
         * 2. 'left' and 'right' are 'auto' and 'width' is not 'auto', then if
         *    the 'direction' property of the containing block is 'ltr' set
         *    'left' to the static position, otherwise set 'right' to the
         *    static position. Then solve for 'left' (if 'direction is 'rtl')
         *    or 'right' (if 'direction' is 'ltr').
         * ------------------------------------------------------------------
         *
         * 3. 'width' and 'right' are 'auto' and 'left' is not 'auto', then the
         *    width is shrink-to-fit . Then solve for 'right'
         * 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve
         *    for 'left'
         * 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve
         *    for 'width'
         * 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve
         *    for 'right'
         *
         * Calculation of the shrink-to-fit width is similar to calculating the
         * width of a table cell using the automatic table layout algorithm.
         * Roughly: calculate the preferred width by formatting the content
         * without breaking lines other than where explicit line breaks occur,
         * and also calculate the preferred minimum width, e.g., by trying all
         * possible line breaks. CSS 2.1 does not define the exact algorithm.
         * Thirdly, calculate the available width: this is found by solving
         * for 'width' after setting 'left' (in case 1) or 'right' (in case 3)
         * to 0.
         *
         * Then the shrink-to-fit width is:
         * min(max(preferred minimum width, available width), preferred width).
        \*--------------------------------------------------------------------*/
        // NOTE: For rules 3 and 6 it is not necessary to solve for 'right'
        // because the value is not used for any further calculations.

        // Calculate margins, 'auto' margins are ignored.
        marginLogicalLeftValue = minimumValueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
        marginLogicalRightValue = minimumValueForLength(marginLogicalRight, containerRelativeLogicalWidth);

        const LayoutUnit availableSpace = containerLogicalWidth - (marginLogicalLeftValue + marginLogicalRightValue + bordersPlusPadding);

        // FIXME: Is there a faster way to find the correct case?
        // Use rule/case that applies.
        if (logicalLeftIsAuto && logicalWidthIsAuto && !logicalRightIsAuto) {
            // RULE 1: (use shrink-to-fit for width, and solve of left)
            LayoutUnit logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

            // FIXME: would it be better to have shrink-to-fit in one step?
            LayoutUnit preferredWidth = maxPreferredLogicalWidth() - bordersPlusPadding;
            LayoutUnit preferredMinWidth = minPreferredLogicalWidth() - bordersPlusPadding;
            LayoutUnit availableWidth = availableSpace - logicalRightValue;
            computedValues.m_extent = min(max(preferredMinWidth, availableWidth), preferredWidth);
            logicalLeftValue = availableSpace - (computedValues.m_extent + logicalRightValue);
        } else if (!logicalLeftIsAuto && logicalWidthIsAuto && logicalRightIsAuto) {
            // RULE 3: (use shrink-to-fit for width, and no need solve of right)
            logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);

            shrinkToFitWidth(availableSpace, logicalLeftValue, bordersPlusPadding, computedValues);
        } else if (logicalLeftIsAuto && !logicalWidthIsAuto && !logicalRightIsAuto) {
            // RULE 4: (solve for left)
            computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
            logicalLeftValue = availableSpace - (computedValues.m_extent + valueForLength(logicalRight, containerLogicalWidth));
        } else if (!logicalLeftIsAuto && logicalWidthIsAuto && !logicalRightIsAuto) {
            // RULE 5: (solve for width)
            logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
            if (autoWidthShouldFitContent())
                shrinkToFitWidth(availableSpace, logicalLeftValue, bordersPlusPadding, computedValues);
            else
                computedValues.m_extent = availableSpace - (logicalLeftValue + valueForLength(logicalRight, containerLogicalWidth));
        } else if (!logicalLeftIsAuto && !logicalWidthIsAuto && logicalRightIsAuto) {
            // RULE 6: (no need solve for right)
            logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
            computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
        }
    }

    // Use computed values to calculate the horizontal position.

    // FIXME: This hack is needed to calculate the  logical left position for a 'rtl' relatively
    // positioned, inline because right now, it is using the logical left position
    // of the first line box when really it should use the last line box.  When
    // this is fixed elsewhere, this block should be removed.
    if (containerBlock->isRenderInline() && !containerBlock->style()->isLeftToRightDirection()) {
        const RenderInline* flow = toRenderInline(containerBlock);
        InlineFlowBox* firstLine = flow->firstLineBox();
        InlineFlowBox* lastLine = flow->lastLineBox();
        if (firstLine && lastLine && firstLine != lastLine) {
            computedValues.m_position = logicalLeftValue + marginLogicalLeftValue + lastLine->borderLogicalLeft() + (lastLine->logicalLeft() - firstLine->logicalLeft());
            return;
        }
    }

    if (containerBlock->isBox() && toRenderBox(containerBlock)->scrollsOverflowY() && containerBlock->style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft()) {
        logicalLeftValue = logicalLeftValue + toRenderBox(containerBlock)->verticalScrollbarWidth();
    }

    computedValues.m_position = logicalLeftValue + marginLogicalLeftValue;
    computeLogicalLeftPositionedOffset(computedValues.m_position, this, computedValues.m_extent, containerBlock, containerLogicalWidth);
}

static void computeBlockStaticDistance(Length& logicalTop, Length& logicalBottom, const RenderBox* child, const RenderBoxModelObject* containerBlock)
{
    if (!logicalTop.isAuto() || !logicalBottom.isAuto())
        return;

    // FIXME: The static distance computation has not been patched for mixed writing modes.
    LayoutUnit staticLogicalTop = child->layer()->staticBlockPosition() - containerBlock->borderBefore();
    for (RenderObject* curr = child->parent(); curr && curr != containerBlock; curr = curr->container()) {
        if (curr->isBox() && !curr->isTableRow())
            staticLogicalTop += toRenderBox(curr)->logicalTop();
    }
    logicalTop.setValue(Fixed, staticLogicalTop);
}

void RenderBox::computePositionedLogicalHeight(LogicalExtentComputedValues& computedValues) const
{
    if (isReplaced()) {
        computePositionedLogicalHeightReplaced(computedValues);
        return;
    }

    // The following is based off of the W3C Working Draft from April 11, 2006 of
    // CSS 2.1: Section 10.6.4 "Absolutely positioned, non-replaced elements"
    // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-non-replaced-height>
    // (block-style-comments in this function and in computePositionedLogicalHeightUsing()
    // correspond to text from the spec)


    // We don't use containingBlock(), since we may be positioned by an enclosing relpositioned inline.
    const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());

    const LayoutUnit containerLogicalHeight = containingBlockLogicalHeightForPositioned(containerBlock);

    RenderStyle* styleToUse = style();
    const LayoutUnit bordersPlusPadding = borderAndPaddingLogicalHeight();
    const Length marginBefore = styleToUse->marginBefore();
    const Length marginAfter = styleToUse->marginAfter();
    Length logicalTopLength = styleToUse->logicalTop();
    Length logicalBottomLength = styleToUse->logicalBottom();

    /*---------------------------------------------------------------------------*\
     * For the purposes of this section and the next, the term "static position"
     * (of an element) refers, roughly, to the position an element would have had
     * in the normal flow. More precisely, the static position for 'top' is the
     * distance from the top edge of the containing block to the top margin edge
     * of a hypothetical box that would have been the first box of the element if
     * its 'position' property had been 'static' and 'float' had been 'none'. The
     * value is negative if the hypothetical box is above the containing block.
     *
     * But rather than actually calculating the dimensions of that hypothetical
     * box, user agents are free to make a guess at its probable position.
     *
     * For the purposes of calculating the static position, the containing block
     * of fixed positioned elements is the initial containing block instead of
     * the viewport.
    \*---------------------------------------------------------------------------*/

    // see FIXME 1
    // Calculate the static distance if needed.
    computeBlockStaticDistance(logicalTopLength, logicalBottomLength, this, containerBlock);

    // Calculate constraint equation values for 'height' case.
    LayoutUnit logicalHeight = computedValues.m_extent;
    computePositionedLogicalHeightUsing(styleToUse->logicalHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
                                        logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
                                        computedValues);

    // Avoid doing any work in the common case (where the values of min-height and max-height are their defaults).
    // see FIXME 2

    // Calculate constraint equation values for 'max-height' case.
    if (!styleToUse->logicalMaxHeight().isUndefined()) {
        LogicalExtentComputedValues maxValues;

        computePositionedLogicalHeightUsing(styleToUse->logicalMaxHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
                                            logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
                                            maxValues);

        if (computedValues.m_extent > maxValues.m_extent) {
            computedValues.m_extent = maxValues.m_extent;
            computedValues.m_position = maxValues.m_position;
            computedValues.m_margins.m_before = maxValues.m_margins.m_before;
            computedValues.m_margins.m_after = maxValues.m_margins.m_after;
        }
    }

    // Calculate constraint equation values for 'min-height' case.
    if (!styleToUse->logicalMinHeight().isZero() || styleToUse->logicalMinHeight().isIntrinsic()) {
        LogicalExtentComputedValues minValues;

        computePositionedLogicalHeightUsing(styleToUse->logicalMinHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
                                            logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
                                            minValues);

        if (computedValues.m_extent < minValues.m_extent) {
            computedValues.m_extent = minValues.m_extent;
            computedValues.m_position = minValues.m_position;
            computedValues.m_margins.m_before = minValues.m_margins.m_before;
            computedValues.m_margins.m_after = minValues.m_margins.m_after;
        }
    }

    // Set final height value.
    computedValues.m_extent += bordersPlusPadding;
}

static void computeLogicalTopPositionedOffset(LayoutUnit& logicalTopPos, const RenderBox* child, LayoutUnit logicalHeightValue, const RenderBoxModelObject* containerBlock, LayoutUnit containerLogicalHeight)
{
    // Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space. If the containing block is flipped
    // along this axis, then we need to flip the coordinate.  This can only happen if the containing block is both a flipped mode and perpendicular to us.
    if ((child->style()->isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() != containerBlock->isHorizontalWritingMode())
        || (child->style()->isFlippedBlocksWritingMode() != containerBlock->style()->isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() == containerBlock->isHorizontalWritingMode()))
        logicalTopPos = containerLogicalHeight - logicalHeightValue - logicalTopPos;

    // Our offset is from the logical bottom edge in a flipped environment, e.g., right for vertical-rl and bottom for horizontal-bt.
    if (containerBlock->style()->isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() == containerBlock->isHorizontalWritingMode()) {
        if (child->isHorizontalWritingMode())
            logicalTopPos += containerBlock->borderBottom();
        else
            logicalTopPos += containerBlock->borderRight();
    } else {
        if (child->isHorizontalWritingMode())
            logicalTopPos += containerBlock->borderTop();
        else
            logicalTopPos += containerBlock->borderLeft();
    }
}

void RenderBox::computePositionedLogicalHeightUsing(Length logicalHeightLength, const RenderBoxModelObject* containerBlock,
                                                    LayoutUnit containerLogicalHeight, LayoutUnit bordersPlusPadding, LayoutUnit logicalHeight,
                                                    Length logicalTop, Length logicalBottom, Length marginBefore, Length marginAfter,
                                                    LogicalExtentComputedValues& computedValues) const
{
    // 'top' and 'bottom' cannot both be 'auto' because 'top would of been
    // converted to the static position in computePositionedLogicalHeight()
    ASSERT(!(logicalTop.isAuto() && logicalBottom.isAuto()));

    LayoutUnit logicalHeightValue;
    LayoutUnit contentLogicalHeight = logicalHeight - bordersPlusPadding;

    const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);

    LayoutUnit logicalTopValue = 0;

    bool logicalHeightIsAuto = logicalHeightLength.isAuto();
    bool logicalTopIsAuto = logicalTop.isAuto();
    bool logicalBottomIsAuto = logicalBottom.isAuto();

    LayoutUnit resolvedLogicalHeight;
    // Height is never unsolved for tables.
    if (isTable()) {
        resolvedLogicalHeight = contentLogicalHeight;
        logicalHeightIsAuto = false;
    } else {
        if (logicalHeightLength.isIntrinsic())
            resolvedLogicalHeight = computeIntrinsicLogicalContentHeightUsing(logicalHeightLength, contentLogicalHeight, bordersPlusPadding);
        else
            resolvedLogicalHeight = adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeightLength, containerLogicalHeight));
    }

    if (!logicalTopIsAuto && !logicalHeightIsAuto && !logicalBottomIsAuto) {
        /*-----------------------------------------------------------------------*\
         * If none of the three are 'auto': If both 'margin-top' and 'margin-
         * bottom' are 'auto', solve the equation under the extra constraint that
         * the two margins get equal values. If one of 'margin-top' or 'margin-
         * bottom' is 'auto', solve the equation for that value. If the values
         * are over-constrained, ignore the value for 'bottom' and solve for that
         * value.
        \*-----------------------------------------------------------------------*/
        // NOTE:  It is not necessary to solve for 'bottom' in the over constrained
        // case because the value is not used for any further calculations.

        logicalHeightValue = resolvedLogicalHeight;
        logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);

        const LayoutUnit availableSpace = containerLogicalHeight - (logicalTopValue + logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight) + bordersPlusPadding);

        // Margins are now the only unknown
        if (marginBefore.isAuto() && marginAfter.isAuto()) {
            // Both margins auto, solve for equality
            // NOTE: This may result in negative values.
            computedValues.m_margins.m_before = availableSpace / 2; // split the difference
            computedValues.m_margins.m_after = availableSpace - computedValues.m_margins.m_before; // account for odd valued differences
        } else if (marginBefore.isAuto()) {
            // Solve for top margin
            computedValues.m_margins.m_after = valueForLength(marginAfter, containerRelativeLogicalWidth);
            computedValues.m_margins.m_before = availableSpace - computedValues.m_margins.m_after;
        } else if (marginAfter.isAuto()) {
            // Solve for bottom margin
            computedValues.m_margins.m_before = valueForLength(marginBefore, containerRelativeLogicalWidth);
            computedValues.m_margins.m_after = availableSpace - computedValues.m_margins.m_before;
        } else {
            // Over-constrained, (no need solve for bottom)
            computedValues.m_margins.m_before = valueForLength(marginBefore, containerRelativeLogicalWidth);
            computedValues.m_margins.m_after = valueForLength(marginAfter, containerRelativeLogicalWidth);
        }
    } else {
        /*--------------------------------------------------------------------*\
         * Otherwise, set 'auto' values for 'margin-top' and 'margin-bottom'
         * to 0, and pick the one of the following six rules that applies.
         *
         * 1. 'top' and 'height' are 'auto' and 'bottom' is not 'auto', then
         *    the height is based on the content, and solve for 'top'.
         *
         *              OMIT RULE 2 AS IT SHOULD NEVER BE HIT
         * ------------------------------------------------------------------
         * 2. 'top' and 'bottom' are 'auto' and 'height' is not 'auto', then
         *    set 'top' to the static position, and solve for 'bottom'.
         * ------------------------------------------------------------------
         *
         * 3. 'height' and 'bottom' are 'auto' and 'top' is not 'auto', then
         *    the height is based on the content, and solve for 'bottom'.
         * 4. 'top' is 'auto', 'height' and 'bottom' are not 'auto', and
         *    solve for 'top'.
         * 5. 'height' is 'auto', 'top' and 'bottom' are not 'auto', and
         *    solve for 'height'.
         * 6. 'bottom' is 'auto', 'top' and 'height' are not 'auto', and
         *    solve for 'bottom'.
        \*--------------------------------------------------------------------*/
        // NOTE: For rules 3 and 6 it is not necessary to solve for 'bottom'
        // because the value is not used for any further calculations.

        // Calculate margins, 'auto' margins are ignored.
        computedValues.m_margins.m_before = minimumValueForLength(marginBefore, containerRelativeLogicalWidth);
        computedValues.m_margins.m_after = minimumValueForLength(marginAfter, containerRelativeLogicalWidth);

        const LayoutUnit availableSpace = containerLogicalHeight - (computedValues.m_margins.m_before + computedValues.m_margins.m_after + bordersPlusPadding);

        // Use rule/case that applies.
        if (logicalTopIsAuto && logicalHeightIsAuto && !logicalBottomIsAuto) {
            // RULE 1: (height is content based, solve of top)
            logicalHeightValue = contentLogicalHeight;
            logicalTopValue = availableSpace - (logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight));
        } else if (!logicalTopIsAuto && logicalHeightIsAuto && logicalBottomIsAuto) {
            // RULE 3: (height is content based, no need solve of bottom)
            logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
            logicalHeightValue = contentLogicalHeight;
        } else if (logicalTopIsAuto && !logicalHeightIsAuto && !logicalBottomIsAuto) {
            // RULE 4: (solve of top)
            logicalHeightValue = resolvedLogicalHeight;
            logicalTopValue = availableSpace - (logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight));
        } else if (!logicalTopIsAuto && logicalHeightIsAuto && !logicalBottomIsAuto) {
            // RULE 5: (solve of height)
            logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
            logicalHeightValue = max<LayoutUnit>(0, availableSpace - (logicalTopValue + valueForLength(logicalBottom, containerLogicalHeight)));
        } else if (!logicalTopIsAuto && !logicalHeightIsAuto && logicalBottomIsAuto) {
            // RULE 6: (no need solve of bottom)
            logicalHeightValue = resolvedLogicalHeight;
            logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
        }
    }
    computedValues.m_extent = logicalHeightValue;

    // Use computed values to calculate the vertical position.
    computedValues.m_position = logicalTopValue + computedValues.m_margins.m_before;
    computeLogicalTopPositionedOffset(computedValues.m_position, this, logicalHeightValue, containerBlock, containerLogicalHeight);
}

void RenderBox::computePositionedLogicalWidthReplaced(LogicalExtentComputedValues& computedValues) const
{
    // The following is based off of the W3C Working Draft from April 11, 2006 of
    // CSS 2.1: Section 10.3.8 "Absolutely positioned, replaced elements"
    // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-replaced-width>
    // (block-style-comments in this function correspond to text from the spec and
    // the numbers correspond to numbers in spec)

    // We don't use containingBlock(), since we may be positioned by an enclosing
    // relative positioned inline.
    const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());

    const LayoutUnit containerLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock);
    const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);

    // To match WinIE, in quirks mode use the parent's 'direction' property
    // instead of the the container block's.
    TextDirection containerDirection = containerBlock->style()->direction();

    // Variables to solve.
    bool isHorizontal = isHorizontalWritingMode();
    Length logicalLeft = style()->logicalLeft();
    Length logicalRight = style()->logicalRight();
    Length marginLogicalLeft = isHorizontal ? style()->marginLeft() : style()->marginTop();
    Length marginLogicalRight = isHorizontal ? style()->marginRight() : style()->marginBottom();
    LayoutUnit& marginLogicalLeftAlias = style()->isLeftToRightDirection() ? computedValues.m_margins.m_start : computedValues.m_margins.m_end;
    LayoutUnit& marginLogicalRightAlias = style()->isLeftToRightDirection() ? computedValues.m_margins.m_end : computedValues.m_margins.m_start;

    /*-----------------------------------------------------------------------*\
     * 1. The used value of 'width' is determined as for inline replaced
     *    elements.
    \*-----------------------------------------------------------------------*/
    // NOTE: This value of width is FINAL in that the min/max width calculations
    // are dealt with in computeReplacedWidth().  This means that the steps to produce
    // correct max/min in the non-replaced version, are not necessary.
    computedValues.m_extent = computeReplacedLogicalWidth() + borderAndPaddingLogicalWidth();

    const LayoutUnit availableSpace = containerLogicalWidth - computedValues.m_extent;

    /*-----------------------------------------------------------------------*\
     * 2. If both 'left' and 'right' have the value 'auto', then if 'direction'
     *    of the containing block is 'ltr', set 'left' to the static position;
     *    else if 'direction' is 'rtl', set 'right' to the static position.
    \*-----------------------------------------------------------------------*/
    // see FIXME 1
    computeInlineStaticDistance(logicalLeft, logicalRight, this, containerBlock, containerLogicalWidth);

    /*-----------------------------------------------------------------------*\
     * 3. If 'left' or 'right' are 'auto', replace any 'auto' on 'margin-left'
     *    or 'margin-right' with '0'.
    \*-----------------------------------------------------------------------*/
    if (logicalLeft.isAuto() || logicalRight.isAuto()) {
        if (marginLogicalLeft.isAuto())
            marginLogicalLeft.setValue(Fixed, 0);
        if (marginLogicalRight.isAuto())
            marginLogicalRight.setValue(Fixed, 0);
    }

    /*-----------------------------------------------------------------------*\
     * 4. If at this point both 'margin-left' and 'margin-right' are still
     *    'auto', solve the equation under the extra constraint that the two
     *    margins must get equal values, unless this would make them negative,
     *    in which case when the direction of the containing block is 'ltr'
     *    ('rtl'), set 'margin-left' ('margin-right') to zero and solve for
     *    'margin-right' ('margin-left').
    \*-----------------------------------------------------------------------*/
    LayoutUnit logicalLeftValue = 0;
    LayoutUnit logicalRightValue = 0;

    if (marginLogicalLeft.isAuto() && marginLogicalRight.isAuto()) {
        // 'left' and 'right' cannot be 'auto' due to step 3
        ASSERT(!(logicalLeft.isAuto() && logicalRight.isAuto()));

        logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
        logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

        LayoutUnit difference = availableSpace - (logicalLeftValue + logicalRightValue);
        if (difference > 0) {
            marginLogicalLeftAlias = difference / 2; // split the difference
            marginLogicalRightAlias = difference - marginLogicalLeftAlias; // account for odd valued differences
        } else {
            // Use the containing block's direction rather than the parent block's
            // per CSS 2.1 reference test abspos-replaced-width-margin-000.
            if (containerDirection == LTR) {
                marginLogicalLeftAlias = 0;
                marginLogicalRightAlias = difference; // will be negative
            } else {
                marginLogicalLeftAlias = difference; // will be negative
                marginLogicalRightAlias = 0;
            }
        }

    /*-----------------------------------------------------------------------*\
     * 5. If at this point there is an 'auto' left, solve the equation for
     *    that value.
    \*-----------------------------------------------------------------------*/
    } else if (logicalLeft.isAuto()) {
        marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
        marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
        logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

        // Solve for 'left'
        logicalLeftValue = availableSpace - (logicalRightValue + marginLogicalLeftAlias + marginLogicalRightAlias);
    } else if (logicalRight.isAuto()) {
        marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
        marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
        logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);

        // Solve for 'right'
        logicalRightValue = availableSpace - (logicalLeftValue + marginLogicalLeftAlias + marginLogicalRightAlias);
    } else if (marginLogicalLeft.isAuto()) {
        marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
        logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
        logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

        // Solve for 'margin-left'
        marginLogicalLeftAlias = availableSpace - (logicalLeftValue + logicalRightValue + marginLogicalRightAlias);
    } else if (marginLogicalRight.isAuto()) {
        marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
        logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
        logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

        // Solve for 'margin-right'
        marginLogicalRightAlias = availableSpace - (logicalLeftValue + logicalRightValue + marginLogicalLeftAlias);
    } else {
        // Nothing is 'auto', just calculate the values.
        marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
        marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
        logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
        logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
        // If the containing block is right-to-left, then push the left position as far to the right as possible
        if (containerDirection == RTL) {
            int totalLogicalWidth = computedValues.m_extent + logicalLeftValue + logicalRightValue +  marginLogicalLeftAlias + marginLogicalRightAlias;
            logicalLeftValue = containerLogicalWidth - (totalLogicalWidth - logicalLeftValue);
        }
    }

    /*-----------------------------------------------------------------------*\
     * 6. If at this point the values are over-constrained, ignore the value
     *    for either 'left' (in case the 'direction' property of the
     *    containing block is 'rtl') or 'right' (in case 'direction' is
     *    'ltr') and solve for that value.
    \*-----------------------------------------------------------------------*/
    // NOTE: Constraints imposed by the width of the containing block and its content have already been accounted for above.

    // FIXME: Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space, so that
    // can make the result here rather complicated to compute.

    // Use computed values to calculate the horizontal position.

    // FIXME: This hack is needed to calculate the logical left position for a 'rtl' relatively
    // positioned, inline containing block because right now, it is using the logical left position
    // of the first line box when really it should use the last line box.  When
    // this is fixed elsewhere, this block should be removed.
    if (containerBlock->isRenderInline() && !containerBlock->style()->isLeftToRightDirection()) {
        const RenderInline* flow = toRenderInline(containerBlock);
        InlineFlowBox* firstLine = flow->firstLineBox();
        InlineFlowBox* lastLine = flow->lastLineBox();
        if (firstLine && lastLine && firstLine != lastLine) {
            computedValues.m_position = logicalLeftValue + marginLogicalLeftAlias + lastLine->borderLogicalLeft() + (lastLine->logicalLeft() - firstLine->logicalLeft());
            return;
        }
    }

    LayoutUnit logicalLeftPos = logicalLeftValue + marginLogicalLeftAlias;
    computeLogicalLeftPositionedOffset(logicalLeftPos, this, computedValues.m_extent, containerBlock, containerLogicalWidth);
    computedValues.m_position = logicalLeftPos;
}

void RenderBox::computePositionedLogicalHeightReplaced(LogicalExtentComputedValues& computedValues) const
{
    // The following is based off of the W3C Working Draft from April 11, 2006 of
    // CSS 2.1: Section 10.6.5 "Absolutely positioned, replaced elements"
    // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-replaced-height>
    // (block-style-comments in this function correspond to text from the spec and
    // the numbers correspond to numbers in spec)

    // We don't use containingBlock(), since we may be positioned by an enclosing relpositioned inline.
    const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());

    const LayoutUnit containerLogicalHeight = containingBlockLogicalHeightForPositioned(containerBlock);
    const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);

    // Variables to solve.
    Length marginBefore = style()->marginBefore();
    Length marginAfter = style()->marginAfter();
    LayoutUnit& marginBeforeAlias = computedValues.m_margins.m_before;
    LayoutUnit& marginAfterAlias = computedValues.m_margins.m_after;

    Length logicalTop = style()->logicalTop();
    Length logicalBottom = style()->logicalBottom();

    /*-----------------------------------------------------------------------*\
     * 1. The used value of 'height' is determined as for inline replaced
     *    elements.
    \*-----------------------------------------------------------------------*/
    // NOTE: This value of height is FINAL in that the min/max height calculations
    // are dealt with in computeReplacedHeight().  This means that the steps to produce
    // correct max/min in the non-replaced version, are not necessary.
    computedValues.m_extent = computeReplacedLogicalHeight() + borderAndPaddingLogicalHeight();
    const LayoutUnit availableSpace = containerLogicalHeight - computedValues.m_extent;

    /*-----------------------------------------------------------------------*\
     * 2. If both 'top' and 'bottom' have the value 'auto', replace 'top'
     *    with the element's static position.
    \*-----------------------------------------------------------------------*/
    // see FIXME 1
    computeBlockStaticDistance(logicalTop, logicalBottom, this, containerBlock);

    /*-----------------------------------------------------------------------*\
     * 3. If 'bottom' is 'auto', replace any 'auto' on 'margin-top' or
     *    'margin-bottom' with '0'.
    \*-----------------------------------------------------------------------*/
    // FIXME: The spec. says that this step should only be taken when bottom is
    // auto, but if only top is auto, this makes step 4 impossible.
    if (logicalTop.isAuto() || logicalBottom.isAuto()) {
        if (marginBefore.isAuto())
            marginBefore.setValue(Fixed, 0);
        if (marginAfter.isAuto())
            marginAfter.setValue(Fixed, 0);
    }

    /*-----------------------------------------------------------------------*\
     * 4. If at this point both 'margin-top' and 'margin-bottom' are still
     *    'auto', solve the equation under the extra constraint that the two
     *    margins must get equal values.
    \*-----------------------------------------------------------------------*/
    LayoutUnit logicalTopValue = 0;
    LayoutUnit logicalBottomValue = 0;

    if (marginBefore.isAuto() && marginAfter.isAuto()) {
        // 'top' and 'bottom' cannot be 'auto' due to step 2 and 3 combined.
        ASSERT(!(logicalTop.isAuto() || logicalBottom.isAuto()));

        logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
        logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

        LayoutUnit difference = availableSpace - (logicalTopValue + logicalBottomValue);
        // NOTE: This may result in negative values.
        marginBeforeAlias =  difference / 2; // split the difference
        marginAfterAlias = difference - marginBeforeAlias; // account for odd valued differences

    /*-----------------------------------------------------------------------*\
     * 5. If at this point there is only one 'auto' left, solve the equation
     *    for that value.
    \*-----------------------------------------------------------------------*/
    } else if (logicalTop.isAuto()) {
        marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
        marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
        logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

        // Solve for 'top'
        logicalTopValue = availableSpace - (logicalBottomValue + marginBeforeAlias + marginAfterAlias);
    } else if (logicalBottom.isAuto()) {
        marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
        marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
        logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);

        // Solve for 'bottom'
        // NOTE: It is not necessary to solve for 'bottom' because we don't ever
        // use the value.
    } else if (marginBefore.isAuto()) {
        marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
        logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
        logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

        // Solve for 'margin-top'
        marginBeforeAlias = availableSpace - (logicalTopValue + logicalBottomValue + marginAfterAlias);
    } else if (marginAfter.isAuto()) {
        marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
        logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
        logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

        // Solve for 'margin-bottom'
        marginAfterAlias = availableSpace - (logicalTopValue + logicalBottomValue + marginBeforeAlias);
    } else {
        // Nothing is 'auto', just calculate the values.
        marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
        marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
        logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
        // NOTE: It is not necessary to solve for 'bottom' because we don't ever
        // use the value.
     }

    /*-----------------------------------------------------------------------*\
     * 6. If at this point the values are over-constrained, ignore the value
     *    for 'bottom' and solve for that value.
    \*-----------------------------------------------------------------------*/
    // NOTE: It is not necessary to do this step because we don't end up using
    // the value of 'bottom' regardless of whether the values are over-constrained
    // or not.

    // Use computed values to calculate the vertical position.
    LayoutUnit logicalTopPos = logicalTopValue + marginBeforeAlias;
    computeLogicalTopPositionedOffset(logicalTopPos, this, computedValues.m_extent, containerBlock, containerLogicalHeight);
    computedValues.m_position = logicalTopPos;
}

LayoutRect RenderBox::localCaretRect(InlineBox* box, int caretOffset, LayoutUnit* extraWidthToEndOfLine)
{
    // VisiblePositions at offsets inside containers either a) refer to the positions before/after
    // those containers (tables and select elements) or b) refer to the position inside an empty block.
    // They never refer to children.
    // FIXME: Paint the carets inside empty blocks differently than the carets before/after elements.

    LayoutRect rect(location(), LayoutSize(caretWidth, height()));
    bool ltr = box ? box->isLeftToRightDirection() : style()->isLeftToRightDirection();

    if ((!caretOffset) ^ ltr)
        rect.move(LayoutSize(width() - caretWidth, 0));

    if (box) {
        RootInlineBox& rootBox = box->root();
        LayoutUnit top = rootBox.lineTop();
        rect.setY(top);
        rect.setHeight(rootBox.lineBottom() - top);
    }

    // If height of box is smaller than font height, use the latter one,
    // otherwise the caret might become invisible.
    //
    // Also, if the box is not a replaced element, always use the font height.
    // This prevents the "big caret" bug described in:
    // <rdar://problem/3777804> Deleting all content in a document can result in giant tall-as-window insertion point
    //
    // FIXME: ignoring :first-line, missing good reason to take care of
    LayoutUnit fontHeight = style()->fontMetrics().height();
    if (fontHeight > rect.height() || (!isReplaced() && !isTable()))
        rect.setHeight(fontHeight);

    if (extraWidthToEndOfLine)
        *extraWidthToEndOfLine = x() + width() - rect.maxX();

    // Move to local coords
    rect.moveBy(-location());

    // FIXME: Border/padding should be added for all elements but this workaround
    // is needed because we use offsets inside an "atomic" element to represent
    // positions before and after the element in deprecated editing offsets.
    if (node() && !(editingIgnoresContent(node()) || isRenderedTable(node()))) {
        rect.setX(rect.x() + borderLeft() + paddingLeft());
        rect.setY(rect.y() + paddingTop() + borderTop());
    }

    if (!isHorizontalWritingMode())
        return rect.transposedRect();

    return rect;
}

PositionWithAffinity RenderBox::positionForPoint(const LayoutPoint& point)
{
    // no children...return this render object's element, if there is one, and offset 0
    if (!firstChild())
        return createPositionWithAffinity(nonPseudoNode() ? firstPositionInOrBeforeNode(nonPseudoNode()) : Position());

    if (isTable() && nonPseudoNode()) {
        LayoutUnit right = contentWidth() + borderAndPaddingWidth();
        LayoutUnit bottom = contentHeight() + borderAndPaddingHeight();

        if (point.x() < 0 || point.x() > right || point.y() < 0 || point.y() > bottom) {
            if (point.x() <= right / 2)
                return createPositionWithAffinity(firstPositionInOrBeforeNode(nonPseudoNode()));
            return createPositionWithAffinity(lastPositionInOrAfterNode(nonPseudoNode()));
        }
    }

    // Pass off to the closest child.
    LayoutUnit minDist = LayoutUnit::max();
    RenderBox* closestRenderer = 0;
    LayoutPoint adjustedPoint = point;
    if (isTableRow())
        adjustedPoint.moveBy(location());

    for (RenderObject* renderObject = firstChild(); renderObject; renderObject = renderObject->nextSibling()) {
        if ((!renderObject->firstChild() && !renderObject->isInline() && !renderObject->isRenderBlockFlow() )
            || renderObject->style()->visibility() != VISIBLE)
            continue;

        if (!renderObject->isBox())
            continue;

        RenderBox* renderer = toRenderBox(renderObject);

        LayoutUnit top = renderer->borderTop() + renderer->paddingTop() + (isTableRow() ? LayoutUnit() : renderer->y());
        LayoutUnit bottom = top + renderer->contentHeight();
        LayoutUnit left = renderer->borderLeft() + renderer->paddingLeft() + (isTableRow() ? LayoutUnit() : renderer->x());
        LayoutUnit right = left + renderer->contentWidth();

        if (point.x() <= right && point.x() >= left && point.y() <= top && point.y() >= bottom) {
            if (renderer->isTableRow())
                return renderer->positionForPoint(point + adjustedPoint - renderer->locationOffset());
            return renderer->positionForPoint(point - renderer->locationOffset());
        }

        // Find the distance from (x, y) to the box.  Split the space around the box into 8 pieces
        // and use a different compare depending on which piece (x, y) is in.
        LayoutPoint cmp;
        if (point.x() > right) {
            if (point.y() < top)
                cmp = LayoutPoint(right, top);
            else if (point.y() > bottom)
                cmp = LayoutPoint(right, bottom);
            else
                cmp = LayoutPoint(right, point.y());
        } else if (point.x() < left) {
            if (point.y() < top)
                cmp = LayoutPoint(left, top);
            else if (point.y() > bottom)
                cmp = LayoutPoint(left, bottom);
            else
                cmp = LayoutPoint(left, point.y());
        } else {
            if (point.y() < top)
                cmp = LayoutPoint(point.x(), top);
            else
                cmp = LayoutPoint(point.x(), bottom);
        }

        LayoutSize difference = cmp - point;

        LayoutUnit dist = difference.width() * difference.width() + difference.height() * difference.height();
        if (dist < minDist) {
            closestRenderer = renderer;
            minDist = dist;
        }
    }

    if (closestRenderer)
        return closestRenderer->positionForPoint(adjustedPoint - closestRenderer->locationOffset());
    return createPositionWithAffinity(firstPositionInOrBeforeNode(nonPseudoNode()));
}

bool RenderBox::shrinkToAvoidFloats() const
{
    // Floating objects don't shrink.  Objects that don't avoid floats don't shrink.  Marquees don't shrink.
    if ((isInline() && !isMarquee()) || !avoidsFloats() || isFloating())
        return false;

    // Only auto width objects can possibly shrink to avoid floats.
    return style()->width().isAuto();
}

bool RenderBox::avoidsFloats() const
{
    return isReplaced() || hasOverflowClip() || isHR() || isLegend() || isWritingModeRoot() || isFlexItemIncludingDeprecated();
}

void RenderBox::markForPaginationRelayoutIfNeeded(SubtreeLayoutScope& layoutScope)
{
    ASSERT(!needsLayout());
    // If fragmentation height has changed, we need to lay out. No need to enter the renderer if it
    // is childless, though.
    if (view()->layoutState()->pageLogicalHeightChanged() && firstChild())
        layoutScope.setChildNeedsLayout(this);
}

void RenderBox::addVisualEffectOverflow()
{
    if (!style()->boxShadow() && !style()->hasBorderImageOutsets() && !style()->hasOutline())
        return;

    bool isFlipped = style()->isFlippedBlocksWritingMode();
    bool isHorizontal = isHorizontalWritingMode();

    LayoutRect borderBox = borderBoxRect();
    LayoutUnit overflowMinX = borderBox.x();
    LayoutUnit overflowMaxX = borderBox.maxX();
    LayoutUnit overflowMinY = borderBox.y();
    LayoutUnit overflowMaxY = borderBox.maxY();

    // Compute box-shadow overflow first.
    if (style()->boxShadow()) {
        LayoutUnit shadowLeft;
        LayoutUnit shadowRight;
        LayoutUnit shadowTop;
        LayoutUnit shadowBottom;
        style()->getBoxShadowExtent(shadowTop, shadowRight, shadowBottom, shadowLeft);

        // In flipped blocks writing modes such as vertical-rl, the physical right shadow value is actually at the lower x-coordinate.
        overflowMinX = borderBox.x() + ((!isFlipped || isHorizontal) ? shadowLeft : -shadowRight);
        overflowMaxX = borderBox.maxX() + ((!isFlipped || isHorizontal) ? shadowRight : -shadowLeft);
        overflowMinY = borderBox.y() + ((!isFlipped || !isHorizontal) ? shadowTop : -shadowBottom);
        overflowMaxY = borderBox.maxY() + ((!isFlipped || !isHorizontal) ? shadowBottom : -shadowTop);
    }

    // Now compute border-image-outset overflow.
    if (style()->hasBorderImageOutsets()) {
        LayoutBoxExtent borderOutsets = style()->borderImageOutsets();

        // In flipped blocks writing modes, the physical sides are inverted. For example in vertical-rl, the right
        // border is at the lower x coordinate value.
        overflowMinX = min(overflowMinX, borderBox.x() - ((!isFlipped || isHorizontal) ? borderOutsets.left() : borderOutsets.right()));
        overflowMaxX = max(overflowMaxX, borderBox.maxX() + ((!isFlipped || isHorizontal) ? borderOutsets.right() : borderOutsets.left()));
        overflowMinY = min(overflowMinY, borderBox.y() - ((!isFlipped || !isHorizontal) ? borderOutsets.top() : borderOutsets.bottom()));
        overflowMaxY = max(overflowMaxY, borderBox.maxY() + ((!isFlipped || !isHorizontal) ? borderOutsets.bottom() : borderOutsets.top()));
    }

    if (style()->hasOutline()) {
        LayoutUnit outlineSize = style()->outlineSize();

        overflowMinX = min(overflowMinX, borderBox.x() - outlineSize);
        overflowMaxX = max(overflowMaxX, borderBox.maxX() + outlineSize);
        overflowMinY = min(overflowMinY, borderBox.y() - outlineSize);
        overflowMaxY = max(overflowMaxY, borderBox.maxY() + outlineSize);
    }

    // Add in the final overflow with shadows, outsets and outline combined.
    LayoutRect visualEffectOverflow(overflowMinX, overflowMinY, overflowMaxX - overflowMinX, overflowMaxY - overflowMinY);
    addVisualOverflow(visualEffectOverflow);
}

void RenderBox::addOverflowFromChild(RenderBox* child, const LayoutSize& delta)
{
    // Never allow flow threads to propagate overflow up to a parent.
    if (child->isRenderFlowThread())
        return;

    // Only propagate layout overflow from the child if the child isn't clipping its overflow.  If it is, then
    // its overflow is internal to it, and we don't care about it.  layoutOverflowRectForPropagation takes care of this
    // and just propagates the border box rect instead.
    LayoutRect childLayoutOverflowRect = child->layoutOverflowRectForPropagation(style());
    childLayoutOverflowRect.move(delta);
    addLayoutOverflow(childLayoutOverflowRect);

    // Add in visual overflow from the child.  Even if the child clips its overflow, it may still
    // have visual overflow of its own set from box shadows or reflections.  It is unnecessary to propagate this
    // overflow if we are clipping our own overflow.
    if (child->hasSelfPaintingLayer())
        return;
    LayoutRect childVisualOverflowRect = child->visualOverflowRectForPropagation(style());
    childVisualOverflowRect.move(delta);
    addContentsVisualOverflow(childVisualOverflowRect);
}

void RenderBox::addLayoutOverflow(const LayoutRect& rect)
{
    LayoutRect clientBox = noOverflowRect();
    if (clientBox.contains(rect) || rect.isEmpty())
        return;

    // For overflow clip objects, we don't want to propagate overflow into unreachable areas.
    LayoutRect overflowRect(rect);
    if (hasOverflowClip() || isRenderView()) {
        // Overflow is in the block's coordinate space and thus is flipped for horizontal-bt and vertical-rl
        // writing modes.  At this stage that is actually a simplification, since we can treat horizontal-tb/bt as the same
        // and vertical-lr/rl as the same.
        bool hasTopOverflow = !style()->isLeftToRightDirection() && !isHorizontalWritingMode();
        bool hasLeftOverflow = !style()->isLeftToRightDirection() && isHorizontalWritingMode();
        if (isFlexibleBox() && style()->isReverseFlexDirection()) {
            RenderFlexibleBox* flexibleBox = toRenderFlexibleBox(this);
            if (flexibleBox->isHorizontalFlow())
                hasLeftOverflow = true;
            else
                hasTopOverflow = true;
        }

        if (!hasTopOverflow)
            overflowRect.shiftYEdgeTo(max(overflowRect.y(), clientBox.y()));
        else
            overflowRect.shiftMaxYEdgeTo(min(overflowRect.maxY(), clientBox.maxY()));
        if (!hasLeftOverflow)
            overflowRect.shiftXEdgeTo(max(overflowRect.x(), clientBox.x()));
        else
            overflowRect.shiftMaxXEdgeTo(min(overflowRect.maxX(), clientBox.maxX()));

        // Now re-test with the adjusted rectangle and see if it has become unreachable or fully
        // contained.
        if (clientBox.contains(overflowRect) || overflowRect.isEmpty())
            return;
    }

    if (!m_overflow)
        m_overflow = adoptPtr(new RenderOverflow(clientBox, borderBoxRect()));

    m_overflow->addLayoutOverflow(overflowRect);
}

void RenderBox::addVisualOverflow(const LayoutRect& rect)
{
    LayoutRect borderBox = borderBoxRect();
    if (borderBox.contains(rect) || rect.isEmpty())
        return;

    if (!m_overflow)
        m_overflow = adoptPtr(new RenderOverflow(noOverflowRect(), borderBox));

    m_overflow->addVisualOverflow(rect);
}

void RenderBox::addContentsVisualOverflow(const LayoutRect& rect)
{
    if (!hasOverflowClip()) {
        addVisualOverflow(rect);
        return;
    }

    if (!m_overflow) {
        LayoutRect clientBox = clientBoxRect();
        if (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
            clientBox.move(-verticalScrollbarWidth(), 0);
        m_overflow = adoptPtr(new RenderOverflow(clientBox, borderBoxRect()));
    }
    m_overflow->addContentsVisualOverflow(rect);
}

void RenderBox::clearLayoutOverflow()
{
    if (!m_overflow)
        return;

    if (!hasVisualOverflow() && contentsVisualOverflowRect().isEmpty()) {
        m_overflow.clear();
        return;
    }

    m_overflow->setLayoutOverflow(noOverflowRect());
}

inline static bool percentageLogicalHeightIsResolvable(const RenderBox* box)
{
    return RenderBox::percentageLogicalHeightIsResolvableFromBlock(box->containingBlock(), box->isOutOfFlowPositioned());
}

bool RenderBox::percentageLogicalHeightIsResolvableFromBlock(const RenderBlock* containingBlock, bool isOutOfFlowPositioned)
{
    // In quirks mode, blocks with auto height are skipped, and we keep looking for an enclosing
    // block that may have a specified height and then use it. In strict mode, this violates the
    // specification, which states that percentage heights just revert to auto if the containing
    // block has an auto height. We still skip anonymous containing blocks in both modes, though, and look
    // only at explicit containers.
    const RenderBlock* cb = containingBlock;
    bool inQuirksMode = cb->document().inQuirksMode();
    while (!cb->isRenderView() && !cb->isBody() && !cb->isTableCell() && !cb->isOutOfFlowPositioned() && cb->style()->logicalHeight().isAuto()) {
        if (!inQuirksMode && !cb->isAnonymousBlock())
            break;
        cb = cb->containingBlock();
    }

    // A positioned element that specified both top/bottom or that specifies height should be treated as though it has a height
    // explicitly specified that can be used for any percentage computations.
    // FIXME: We can't just check top/bottom here.
    // https://bugs.webkit.org/show_bug.cgi?id=46500
    bool isOutOfFlowPositionedWithSpecifiedHeight = cb->isOutOfFlowPositioned() && (!cb->style()->logicalHeight().isAuto() || (!cb->style()->top().isAuto() && !cb->style()->bottom().isAuto()));

    // Table cells violate what the CSS spec says to do with heights.  Basically we
    // don't care if the cell specified a height or not.  We just always make ourselves
    // be a percentage of the cell's current content height.
    if (cb->isTableCell())
        return true;

    // Otherwise we only use our percentage height if our containing block had a specified
    // height.
    if (cb->style()->logicalHeight().isFixed())
        return true;
    if (cb->style()->logicalHeight().isPercent() && !isOutOfFlowPositionedWithSpecifiedHeight)
        return percentageLogicalHeightIsResolvableFromBlock(cb->containingBlock(), cb->isOutOfFlowPositioned());
    if (cb->isRenderView() || inQuirksMode || isOutOfFlowPositionedWithSpecifiedHeight)
        return true;
    if (cb->isRoot() && isOutOfFlowPositioned) {
        // Match the positioned objects behavior, which is that positioned objects will fill their viewport
        // always.  Note we could only hit this case by recurring into computePercentageLogicalHeight on a positioned containing block.
        return true;
    }

    return false;
}

bool RenderBox::hasUnsplittableScrollingOverflow() const
{
    // We will paginate as long as we don't scroll overflow in the pagination direction.
    bool isHorizontal = isHorizontalWritingMode();
    if ((isHorizontal && !scrollsOverflowY()) || (!isHorizontal && !scrollsOverflowX()))
        return false;

    // We do have overflow. We'll still be willing to paginate as long as the block
    // has auto logical height, auto or undefined max-logical-height and a zero or auto min-logical-height.
    // Note this is just a heuristic, and it's still possible to have overflow under these
    // conditions, but it should work out to be good enough for common cases. Paginating overflow
    // with scrollbars present is not the end of the world and is what we used to do in the old model anyway.
    return !style()->logicalHeight().isIntrinsicOrAuto()
        || (!style()->logicalMaxHeight().isIntrinsicOrAuto() && !style()->logicalMaxHeight().isUndefined() && (!style()->logicalMaxHeight().isPercent() || percentageLogicalHeightIsResolvable(this)))
        || (!style()->logicalMinHeight().isIntrinsicOrAuto() && style()->logicalMinHeight().isPositive() && (!style()->logicalMinHeight().isPercent() || percentageLogicalHeightIsResolvable(this)));
}

bool RenderBox::isUnsplittableForPagination() const
{
    return isReplaced() || hasUnsplittableScrollingOverflow() || (parent() && isWritingModeRoot());
}

LayoutUnit RenderBox::lineHeight(bool /*firstLine*/, LineDirectionMode direction, LinePositionMode /*linePositionMode*/) const
{
    if (isReplaced())
        return direction == HorizontalLine ? m_marginBox.top() + height() + m_marginBox.bottom() : m_marginBox.right() + width() + m_marginBox.left();
    return 0;
}

int RenderBox::baselinePosition(FontBaseline baselineType, bool /*firstLine*/, LineDirectionMode direction, LinePositionMode linePositionMode) const
{
    ASSERT(linePositionMode == PositionOnContainingLine);
    if (isReplaced()) {
        int result = direction == HorizontalLine ? m_marginBox.top() + height() + m_marginBox.bottom() : m_marginBox.right() + width() + m_marginBox.left();
        if (baselineType == AlphabeticBaseline)
            return result;
        return result - result / 2;
    }
    return 0;
}


RenderLayer* RenderBox::enclosingFloatPaintingLayer() const
{
    const RenderObject* curr = this;
    while (curr) {
        RenderLayer* layer = curr->hasLayer() && curr->isBox() ? toRenderBox(curr)->layer() : 0;
        if (layer && layer->isSelfPaintingLayer())
            return layer;
        curr = curr->parent();
    }
    return 0;
}

LayoutRect RenderBox::logicalVisualOverflowRectForPropagation(RenderStyle* parentStyle) const
{
    LayoutRect rect = visualOverflowRectForPropagation(parentStyle);
    if (!parentStyle->isHorizontalWritingMode())
        return rect.transposedRect();
    return rect;
}

LayoutRect RenderBox::visualOverflowRectForPropagation(RenderStyle* parentStyle) const
{
    // If the writing modes of the child and parent match, then we don't have to
    // do anything fancy. Just return the result.
    LayoutRect rect = visualOverflowRect();
    if (parentStyle->writingMode() == style()->writingMode())
        return rect;

    // We are putting ourselves into our parent's coordinate space.  If there is a flipped block mismatch
    // in a particular axis, then we have to flip the rect along that axis.
    if (style()->writingMode() == RightToLeftWritingMode || parentStyle->writingMode() == RightToLeftWritingMode)
        rect.setX(width() - rect.maxX());
    else if (style()->writingMode() == BottomToTopWritingMode || parentStyle->writingMode() == BottomToTopWritingMode)
        rect.setY(height() - rect.maxY());

    return rect;
}

LayoutRect RenderBox::logicalLayoutOverflowRectForPropagation(RenderStyle* parentStyle) const
{
    LayoutRect rect = layoutOverflowRectForPropagation(parentStyle);
    if (!parentStyle->isHorizontalWritingMode())
        return rect.transposedRect();
    return rect;
}

LayoutRect RenderBox::layoutOverflowRectForPropagation(RenderStyle* parentStyle) const
{
    // Only propagate interior layout overflow if we don't clip it.
    LayoutRect rect = borderBoxRect();
    // We want to include the margin, but only when it adds height. Quirky margins don't contribute height
    // nor do the margins of self-collapsing blocks.
    if (!style()->hasMarginAfterQuirk() && !isSelfCollapsingBlock())
        rect.expand(isHorizontalWritingMode() ? LayoutSize(LayoutUnit(), marginAfter()) : LayoutSize(marginAfter(), LayoutUnit()));

    if (!hasOverflowClip())
        rect.unite(layoutOverflowRect());

    bool hasTransform = hasLayer() && layer()->transform();
    if (isInFlowPositioned() || hasTransform) {
        // If we are relatively positioned or if we have a transform, then we have to convert
        // this rectangle into physical coordinates, apply relative positioning and transforms
        // to it, and then convert it back.
        flipForWritingMode(rect);

        if (hasTransform)
            rect = layer()->currentTransform().mapRect(rect);

        if (isInFlowPositioned())
            rect.move(offsetForInFlowPosition());

        // Now we need to flip back.
        flipForWritingMode(rect);
    }

    // If the writing modes of the child and parent match, then we don't have to
    // do anything fancy. Just return the result.
    if (parentStyle->writingMode() == style()->writingMode())
        return rect;

    // We are putting ourselves into our parent's coordinate space.  If there is a flipped block mismatch
    // in a particular axis, then we have to flip the rect along that axis.
    if (style()->writingMode() == RightToLeftWritingMode || parentStyle->writingMode() == RightToLeftWritingMode)
        rect.setX(width() - rect.maxX());
    else if (style()->writingMode() == BottomToTopWritingMode || parentStyle->writingMode() == BottomToTopWritingMode)
        rect.setY(height() - rect.maxY());

    return rect;
}

LayoutRect RenderBox::noOverflowRect() const
{
    // Because of the special coordinate system used for overflow rectangles and many other
    // rectangles (not quite logical, not quite physical), we need to flip the block progression
    // coordinate in vertical-rl and horizontal-bt writing modes. In other words, the rectangle
    // returned is physical, except for the block direction progression coordinate (y in horizontal
    // writing modes, x in vertical writing modes), which is always "logical top". Apart from the
    // flipping, this method does the same as clientBoxRect().

    const int scrollBarWidth = verticalScrollbarWidth();
    const int scrollBarHeight = horizontalScrollbarHeight();
    LayoutUnit left = borderLeft() + (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft() ? scrollBarWidth : 0);
    LayoutUnit top = borderTop();
    LayoutUnit right = borderRight();
    LayoutUnit bottom = borderBottom();
    LayoutRect rect(left, top, width() - left - right, height() - top - bottom);
    flipForWritingMode(rect);
    // Subtract space occupied by scrollbars. Order is important here: first flip, then subtract
    // scrollbars. This may seem backwards and weird, since one would think that a horizontal
    // scrollbar at the physical bottom in horizontal-bt ought to be at the logical top (physical
    // bottom), between the logical top (physical bottom) border and the logical top (physical
    // bottom) padding. But this is how the rest of the code expects us to behave. This is highly
    // related to https://bugs.webkit.org/show_bug.cgi?id=76129
    // FIXME: when the above mentioned bug is fixed, it should hopefully be possible to call
    // clientBoxRect() or paddingBoxRect() in this method, rather than fiddling with the edges on
    // our own.
    if (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
        rect.contract(0, scrollBarHeight);
    else
        rect.contract(scrollBarWidth, scrollBarHeight);
    return rect;
}

LayoutRect RenderBox::overflowRectForPaintRejection() const
{
    LayoutRect overflowRect = visualOverflowRect();
    if (!m_overflow || !usesCompositedScrolling())
        return overflowRect;

    overflowRect.unite(layoutOverflowRect());
    overflowRect.move(-scrolledContentOffset());
    return overflowRect;
}

LayoutUnit RenderBox::offsetLeft() const
{
    return adjustedPositionRelativeToOffsetParent(topLeftLocation()).x();
}

LayoutUnit RenderBox::offsetTop() const
{
    return adjustedPositionRelativeToOffsetParent(topLeftLocation()).y();
}

LayoutPoint RenderBox::flipForWritingModeForChild(const RenderBox* child, const LayoutPoint& point) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return point;

    // The child is going to add in its x() and y(), so we have to make sure it ends up in
    // the right place.
    if (isHorizontalWritingMode())
        return LayoutPoint(point.x(), point.y() + height() - child->height() - (2 * child->y()));
    return LayoutPoint(point.x() + width() - child->width() - (2 * child->x()), point.y());
}

void RenderBox::flipForWritingMode(LayoutRect& rect) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return;

    if (isHorizontalWritingMode())
        rect.setY(height() - rect.maxY());
    else
        rect.setX(width() - rect.maxX());
}

LayoutUnit RenderBox::flipForWritingMode(LayoutUnit position) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return position;
    return logicalHeight() - position;
}

LayoutPoint RenderBox::flipForWritingMode(const LayoutPoint& position) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return position;
    return isHorizontalWritingMode() ? LayoutPoint(position.x(), height() - position.y()) : LayoutPoint(width() - position.x(), position.y());
}

LayoutPoint RenderBox::flipForWritingModeIncludingColumns(const LayoutPoint& point) const
{
    if (!hasColumns() || !style()->isFlippedBlocksWritingMode())
        return flipForWritingMode(point);
    return toRenderBlock(this)->flipForWritingModeIncludingColumns(point);
}

LayoutSize RenderBox::flipForWritingMode(const LayoutSize& offset) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return offset;
    return isHorizontalWritingMode() ? LayoutSize(offset.width(), height() - offset.height()) : LayoutSize(width() - offset.width(), offset.height());
}

FloatPoint RenderBox::flipForWritingMode(const FloatPoint& position) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return position;
    return isHorizontalWritingMode() ? FloatPoint(position.x(), height() - position.y()) : FloatPoint(width() - position.x(), position.y());
}

void RenderBox::flipForWritingMode(FloatRect& rect) const
{
    if (!style()->isFlippedBlocksWritingMode())
        return;

    if (isHorizontalWritingMode())
        rect.setY(height() - rect.maxY());
    else
        rect.setX(width() - rect.maxX());
}

LayoutPoint RenderBox::topLeftLocation() const
{
    RenderBlock* containerBlock = containingBlock();
    if (!containerBlock || containerBlock == this)
        return location();
    return containerBlock->flipForWritingModeForChild(this, location());
}

LayoutSize RenderBox::topLeftLocationOffset() const
{
    RenderBlock* containerBlock = containingBlock();
    if (!containerBlock || containerBlock == this)
        return locationOffset();

    LayoutRect rect(frameRect());
    containerBlock->flipForWritingMode(rect); // FIXME: This is wrong if we are an absolutely positioned object enclosed by a relative-positioned inline.
    return LayoutSize(rect.x(), rect.y());
}

bool RenderBox::hasRelativeLogicalHeight() const
{
    return style()->logicalHeight().isPercent()
        || style()->logicalMinHeight().isPercent()
        || style()->logicalMaxHeight().isPercent();
}

static void markBoxForRelayoutAfterSplit(RenderBox* box)
{
    // FIXME: The table code should handle that automatically. If not,
    // we should fix it and remove the table part checks.
    if (box->isTable()) {
        // Because we may have added some sections with already computed column structures, we need to
        // sync the table structure with them now. This avoids crashes when adding new cells to the table.
        toRenderTable(box)->forceSectionsRecalc();
    } else if (box->isTableSection())
        toRenderTableSection(box)->setNeedsCellRecalc();

    box->setNeedsLayoutAndPrefWidthsRecalc();
}

RenderObject* RenderBox::splitAnonymousBoxesAroundChild(RenderObject* beforeChild)
{
    bool didSplitParentAnonymousBoxes = false;

    while (beforeChild->parent() != this) {
        RenderBox* boxToSplit = toRenderBox(beforeChild->parent());
        if (boxToSplit->firstChild() != beforeChild && boxToSplit->isAnonymous()) {
            didSplitParentAnonymousBoxes = true;

            // We have to split the parent box into two boxes and move children
            // from |beforeChild| to end into the new post box.
            RenderBox* postBox = boxToSplit->createAnonymousBoxWithSameTypeAs(this);
            postBox->setChildrenInline(boxToSplit->childrenInline());
            RenderBox* parentBox = toRenderBox(boxToSplit->parent());
            // We need to invalidate the |parentBox| before inserting the new node
            // so that the table repainting logic knows the structure is dirty.
            // See for example RenderTableCell:clippedOverflowRectForRepaint.
            markBoxForRelayoutAfterSplit(parentBox);
            parentBox->virtualChildren()->insertChildNode(parentBox, postBox, boxToSplit->nextSibling());
            boxToSplit->moveChildrenTo(postBox, beforeChild, 0, true);

            markBoxForRelayoutAfterSplit(boxToSplit);
            markBoxForRelayoutAfterSplit(postBox);

            beforeChild = postBox;
        } else
            beforeChild = boxToSplit;
    }

    if (didSplitParentAnonymousBoxes)
        markBoxForRelayoutAfterSplit(this);

    ASSERT(beforeChild->parent() == this);
    return beforeChild;
}

LayoutUnit RenderBox::offsetFromLogicalTopOfFirstPage() const
{
    LayoutState* layoutState = view()->layoutState();
    if (layoutState && !layoutState->isPaginated())
        return 0;

    if (!layoutState && !flowThreadContainingBlock())
        return 0;

    RenderBlock* containerBlock = containingBlock();
    return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
}

} // namespace WebCore