Source/core/editing/FrameSelection.cpp

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This source file includes following definitions.
NoXPosForVerticalArrowNavigation
shouldAlwaysUseDirectionalSelection
m_shouldShowBlockCursor
rootEditableElementOrDocumentElement
rootEditableElementOrTreeScopeRootNode
moveTo
moveTo
moveTo
adjustEndpointsAtBidiBoundary
setNonDirectionalSelectionIfNeeded
setSelection
removingNodeRemovesPosition
nodeWillBeRemoved
respondToNodeModification
updatePositionAfterAdoptingTextReplacement
didUpdateCharacterData
updatePostionAfterAdoptingTextNodesMerged
didMergeTextNodes
updatePostionAfterAdoptingTextNodeSplit
didSplitTextNode
updateSelectionIfNeeded
directionOfEnclosingBlock
directionOfSelection
didChangeFocus
willBeModified
positionForPlatform
startForPlatform
endForPlatform
nextWordPositionForPlatform
adjustPositionForUserSelectAll
modifyExtendingRight
modifyExtendingForward
modifyMovingRight
modifyMovingForward
modifyExtendingLeft
modifyExtendingBackward
modifyMovingLeft
modifyMovingBackward
isBoundary
modify
absoluteCaretY
modify
lineDirectionPointForBlockDirectionNavigation
clear
prepareForDestruction
setStart
setEnd
setBase
setExtent
caretRenderer
isNonOrphanedCaret
localCaretRect
absoluteCaretBounds
recomputeCaretRect
invalidateCaretRect
paintCaret
contains
selectFrameElementInParentIfFullySelected
selectAll
setSelectedRange
firstRange
isInPasswordField
notifyAccessibilityForSelectionChange
focusedOrActiveStateChanged
pageActivationChanged
updateSecureKeyboardEntryIfActive
setUseSecureKeyboardEntry
setFocused
isFocusedAndActive
shouldStopBlinkingDueToTypingCommand
updateAppearance
setCaretVisibility
shouldBlinkCaret
caretBlinkTimerFired
notifyRendererOfSelectionChange
isFrameElement
setFocusedNodeIfNeeded
extractSelectedText
selectedText
selectedTextForClipboard
bounds
associatedFormElement
scanForForm
currentForm
revealSelection
setSelectionFromNone
dispatchSelectStart
setShouldShowBlockCursor
didChangeVisibleSelection
startObservingVisibleSelectionChange
stopObservingVisibleSelectionChangeIfNecessary
formatForDebugger
showTreeForThis
showTree
showTree
/*
 * Copyright (C) 2004, 2008, 2009, 2010 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "core/editing/FrameSelection.h"

#include <stdio.h>
#include "HTMLNames.h"
#include "bindings/v8/ExceptionState.h"
#include "core/accessibility/AXObjectCache.h"
#include "core/css/StylePropertySet.h"
#include "core/dom/CharacterData.h"
#include "core/dom/Document.h"
#include "core/dom/Element.h"
#include "core/dom/ElementTraversal.h"
#include "core/dom/NodeTraversal.h"
#include "core/dom/Text.h"
#include "core/editing/Editor.h"
#include "core/editing/InputMethodController.h"
#include "core/editing/RenderedPosition.h"
#include "core/editing/SpellChecker.h"
#include "core/editing/TextIterator.h"
#include "core/editing/TypingCommand.h"
#include "core/editing/VisibleUnits.h"
#include "core/editing/htmlediting.h"
#include "core/frame/DOMWindow.h"
#include "core/frame/LocalFrame.h"
#include "core/html/HTMLBodyElement.h"
#include "core/html/HTMLFormElement.h"
#include "core/html/HTMLFrameElementBase.h"
#include "core/html/HTMLInputElement.h"
#include "core/html/HTMLSelectElement.h"
#include "core/page/EditorClient.h"
#include "core/page/EventHandler.h"
#include "core/page/FocusController.h"
#include "core/page/FrameTree.h"
#include "core/frame/FrameView.h"
#include "core/page/Page.h"
#include "core/frame/Settings.h"
#include "core/page/SpatialNavigation.h"
#include "core/rendering/HitTestRequest.h"
#include "core/rendering/HitTestResult.h"
#include "core/rendering/InlineTextBox.h"
#include "core/rendering/RenderLayer.h"
#include "core/rendering/RenderText.h"
#include "core/rendering/RenderTheme.h"
#include "core/rendering/RenderView.h"
#include "core/rendering/RenderWidget.h"
#include "platform/SecureTextInput.h"
#include "platform/geometry/FloatQuad.h"
#include "platform/graphics/GraphicsContext.h"
#include "wtf/text/CString.h"

#define EDIT_DEBUG 0

namespace WebCore {

using namespace HTMLNames;

static inline LayoutUnit NoXPosForVerticalArrowNavigation()
{
    return LayoutUnit::min();
}

static inline bool shouldAlwaysUseDirectionalSelection(LocalFrame* frame)
{
    return !frame || frame->editor().behavior().shouldConsiderSelectionAsDirectional();
}

FrameSelection::FrameSelection(LocalFrame* frame)
    : m_frame(frame)
    , m_xPosForVerticalArrowNavigation(NoXPosForVerticalArrowNavigation())
    , m_observingVisibleSelection(false)
    , m_granularity(CharacterGranularity)
    , m_caretBlinkTimer(this, &FrameSelection::caretBlinkTimerFired)
    , m_absCaretBoundsDirty(true)
    , m_caretPaint(true)
    , m_isCaretBlinkingSuspended(false)
    , m_focused(frame && frame->page() && frame->page()->focusController().focusedFrame() == frame)
    , m_shouldShowBlockCursor(false)
{
    if (shouldAlwaysUseDirectionalSelection(m_frame))
        m_selection.setIsDirectional(true);
}

FrameSelection::~FrameSelection()
{
    stopObservingVisibleSelectionChangeIfNecessary();
}

Element* FrameSelection::rootEditableElementOrDocumentElement() const
{
    Element* selectionRoot = m_selection.rootEditableElement();
    return selectionRoot ? selectionRoot : m_frame->document()->documentElement();
}

Node* FrameSelection::rootEditableElementOrTreeScopeRootNode() const
{
    Element* selectionRoot = m_selection.rootEditableElement();
    if (selectionRoot)
        return selectionRoot;

    Node* node = m_selection.base().containerNode();
    return node ? &node->treeScope().rootNode() : 0;
}

void FrameSelection::moveTo(const VisiblePosition &pos, EUserTriggered userTriggered, CursorAlignOnScroll align)
{
    SetSelectionOptions options = CloseTyping | ClearTypingStyle | userTriggered;
    setSelection(VisibleSelection(pos.deepEquivalent(), pos.deepEquivalent(), pos.affinity(), m_selection.isDirectional()), options, align);
}

void FrameSelection::moveTo(const VisiblePosition &base, const VisiblePosition &extent, EUserTriggered userTriggered)
{
    const bool selectionHasDirection = true;
    SetSelectionOptions options = CloseTyping | ClearTypingStyle | userTriggered;
    setSelection(VisibleSelection(base.deepEquivalent(), extent.deepEquivalent(), base.affinity(), selectionHasDirection), options);
}

void FrameSelection::moveTo(const Position &pos, EAffinity affinity, EUserTriggered userTriggered)
{
    SetSelectionOptions options = CloseTyping | ClearTypingStyle | userTriggered;
    setSelection(VisibleSelection(pos, affinity, m_selection.isDirectional()), options);
}

static void adjustEndpointsAtBidiBoundary(VisiblePosition& visibleBase, VisiblePosition& visibleExtent)
{
    RenderedPosition base(visibleBase);
    RenderedPosition extent(visibleExtent);

    if (base.isNull() || extent.isNull() || base.isEquivalent(extent))
        return;

    if (base.atLeftBoundaryOfBidiRun()) {
        if (!extent.atRightBoundaryOfBidiRun(base.bidiLevelOnRight())
            && base.isEquivalent(extent.leftBoundaryOfBidiRun(base.bidiLevelOnRight()))) {
            visibleBase = VisiblePosition(base.positionAtLeftBoundaryOfBiDiRun());
            return;
        }
        return;
    }

    if (base.atRightBoundaryOfBidiRun()) {
        if (!extent.atLeftBoundaryOfBidiRun(base.bidiLevelOnLeft())
            && base.isEquivalent(extent.rightBoundaryOfBidiRun(base.bidiLevelOnLeft()))) {
            visibleBase = VisiblePosition(base.positionAtRightBoundaryOfBiDiRun());
            return;
        }
        return;
    }

    if (extent.atLeftBoundaryOfBidiRun() && extent.isEquivalent(base.leftBoundaryOfBidiRun(extent.bidiLevelOnRight()))) {
        visibleExtent = VisiblePosition(extent.positionAtLeftBoundaryOfBiDiRun());
        return;
    }

    if (extent.atRightBoundaryOfBidiRun() && extent.isEquivalent(base.rightBoundaryOfBidiRun(extent.bidiLevelOnLeft()))) {
        visibleExtent = VisiblePosition(extent.positionAtRightBoundaryOfBiDiRun());
        return;
    }
}

void FrameSelection::setNonDirectionalSelectionIfNeeded(const VisibleSelection& passedNewSelection, TextGranularity granularity,
    EndPointsAdjustmentMode endpointsAdjustmentMode)
{
    VisibleSelection newSelection = passedNewSelection;
    bool isDirectional = shouldAlwaysUseDirectionalSelection(m_frame) || newSelection.isDirectional();

    VisiblePosition base = m_originalBase.isNotNull() ? m_originalBase : newSelection.visibleBase();
    VisiblePosition newBase = base;
    VisiblePosition extent = newSelection.visibleExtent();
    VisiblePosition newExtent = extent;
    if (endpointsAdjustmentMode == AdjustEndpointsAtBidiBoundary)
        adjustEndpointsAtBidiBoundary(newBase, newExtent);

    if (newBase != base || newExtent != extent) {
        m_originalBase = base;
        newSelection.setBase(newBase);
        newSelection.setExtent(newExtent);
    } else if (m_originalBase.isNotNull()) {
        if (m_selection.base() == newSelection.base())
            newSelection.setBase(m_originalBase);
        m_originalBase.clear();
    }

    newSelection.setIsDirectional(isDirectional); // Adjusting base and extent will make newSelection always directional
    if (m_selection == newSelection)
        return;

    setSelection(newSelection, granularity);
}

void FrameSelection::setSelection(const VisibleSelection& newSelection, SetSelectionOptions options, CursorAlignOnScroll align, TextGranularity granularity)
{
    bool closeTyping = options & CloseTyping;
    bool shouldClearTypingStyle = options & ClearTypingStyle;
    EUserTriggered userTriggered = selectionOptionsToUserTriggered(options);

    VisibleSelection s = newSelection;
    if (shouldAlwaysUseDirectionalSelection(m_frame))
        s.setIsDirectional(true);

    if (!m_frame) {
        m_selection = s;
        return;
    }

    // <http://bugs.webkit.org/show_bug.cgi?id=23464>: Infinite recursion at FrameSelection::setSelection
    // if document->frame() == m_frame we can get into an infinite loop
    if (s.base().anchorNode()) {
        Document& document = *s.base().document();
        if (document.frame() && document.frame() != m_frame && document != m_frame->document()) {
            RefPtr<LocalFrame> guard = document.frame();
            document.frame()->selection().setSelection(s, options, align, granularity);
            // It's possible that during the above set selection, this FrameSelection has been modified by
            // selectFrameElementInParentIfFullySelected, but that the selection is no longer valid since
            // the frame is about to be destroyed. If this is the case, clear our selection.
            if (guard->hasOneRef() && !m_selection.isNonOrphanedCaretOrRange())
                clear();
            return;
        }
    }

    m_granularity = granularity;

    if (closeTyping)
        TypingCommand::closeTyping(m_frame);

    if (shouldClearTypingStyle)
        clearTypingStyle();

    if (m_selection == s) {
        // Even if selection was not changed, selection offsets may have been changed.
        m_frame->inputMethodController().cancelCompositionIfSelectionIsInvalid();
        notifyRendererOfSelectionChange(userTriggered);
        return;
    }

    VisibleSelection oldSelection = m_selection;

    m_selection = s;
    setCaretRectNeedsUpdate();

    if (!s.isNone() && !(options & DoNotSetFocus))
        setFocusedNodeIfNeeded();

    if (!(options & DoNotUpdateAppearance)) {
        m_frame->document()->updateLayoutIgnorePendingStylesheets();

        // Hits in compositing/overflow/do-not-paint-outline-into-composited-scrolling-contents.html
        DisableCompositingQueryAsserts disabler;
        updateAppearance();
    }

    // Always clear the x position used for vertical arrow navigation.
    // It will be restored by the vertical arrow navigation code if necessary.
    m_xPosForVerticalArrowNavigation = NoXPosForVerticalArrowNavigation();
    selectFrameElementInParentIfFullySelected();
    notifyRendererOfSelectionChange(userTriggered);
    m_frame->editor().respondToChangedSelection(oldSelection, options);
    if (userTriggered == UserTriggered) {
        ScrollAlignment alignment;

        if (m_frame->editor().behavior().shouldCenterAlignWhenSelectionIsRevealed())
            alignment = (align == AlignCursorOnScrollAlways) ? ScrollAlignment::alignCenterAlways : ScrollAlignment::alignCenterIfNeeded;
        else
            alignment = (align == AlignCursorOnScrollAlways) ? ScrollAlignment::alignTopAlways : ScrollAlignment::alignToEdgeIfNeeded;

        revealSelection(alignment, RevealExtent);
    }

    notifyAccessibilityForSelectionChange();
    m_frame->domWindow()->enqueueDocumentEvent(Event::create(EventTypeNames::selectionchange));
}

static bool removingNodeRemovesPosition(Node& node, const Position& position)
{
    if (!position.anchorNode())
        return false;

    if (position.anchorNode() == node)
        return true;

    if (!node.isElementNode())
        return false;

    Element& element = toElement(node);
    return element.containsIncludingShadowDOM(position.anchorNode());
}

void FrameSelection::nodeWillBeRemoved(Node& node)
{
    // There can't be a selection inside a fragment, so if a fragment's node is being removed,
    // the selection in the document that created the fragment needs no adjustment.
    if (isNone() || !node.inActiveDocument())
        return;

    respondToNodeModification(node, removingNodeRemovesPosition(node, m_selection.base()), removingNodeRemovesPosition(node, m_selection.extent()),
        removingNodeRemovesPosition(node, m_selection.start()), removingNodeRemovesPosition(node, m_selection.end()));
}

void FrameSelection::respondToNodeModification(Node& node, bool baseRemoved, bool extentRemoved, bool startRemoved, bool endRemoved)
{
    ASSERT(node.document().isActive());

    bool clearRenderTreeSelection = false;
    bool clearDOMTreeSelection = false;

    if (startRemoved || endRemoved) {
        Position start = m_selection.start();
        Position end = m_selection.end();
        if (startRemoved)
            updatePositionForNodeRemoval(start, node);
        if (endRemoved)
            updatePositionForNodeRemoval(end, node);

        if (start.isNotNull() && end.isNotNull()) {
            if (m_selection.isBaseFirst())
                m_selection.setWithoutValidation(start, end);
            else
                m_selection.setWithoutValidation(end, start);
        } else
            clearDOMTreeSelection = true;

        clearRenderTreeSelection = true;
    } else if (baseRemoved || extentRemoved) {
        // The base and/or extent are about to be removed, but the start and end aren't.
        // Change the base and extent to the start and end, but don't re-validate the
        // selection, since doing so could move the start and end into the node
        // that is about to be removed.
        if (m_selection.isBaseFirst())
            m_selection.setWithoutValidation(m_selection.start(), m_selection.end());
        else
            m_selection.setWithoutValidation(m_selection.end(), m_selection.start());
    } else if (RefPtrWillBeRawPtr<Range> range = m_selection.firstRange()) {
        TrackExceptionState exceptionState;
        Range::CompareResults compareResult = range->compareNode(&node, exceptionState);
        if (!exceptionState.hadException() && (compareResult == Range::NODE_BEFORE_AND_AFTER || compareResult == Range::NODE_INSIDE)) {
            // If we did nothing here, when this node's renderer was destroyed, the rect that it
            // occupied would be invalidated, but, selection gaps that change as a result of
            // the removal wouldn't be invalidated.
            // FIXME: Don't do so much unnecessary invalidation.
            clearRenderTreeSelection = true;
        }
    }

    if (clearRenderTreeSelection)
        m_selection.start().document()->renderView()->clearSelection();

    if (clearDOMTreeSelection)
        setSelection(VisibleSelection(), DoNotSetFocus);
}

static Position updatePositionAfterAdoptingTextReplacement(const Position& position, CharacterData* node, unsigned offset, unsigned oldLength, unsigned newLength)
{
    if (!position.anchorNode() || position.anchorNode() != node || position.anchorType() != Position::PositionIsOffsetInAnchor)
        return position;

    // See: http://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html#Level-2-Range-Mutation
    ASSERT(position.offsetInContainerNode() >= 0);
    unsigned positionOffset = static_cast<unsigned>(position.offsetInContainerNode());
    // Replacing text can be viewed as a deletion followed by insertion.
    if (positionOffset >= offset && positionOffset <= offset + oldLength)
        positionOffset = offset;

    // Adjust the offset if the position is after the end of the deleted contents
    // (positionOffset > offset + oldLength) to avoid having a stale offset.
    if (positionOffset > offset + oldLength)
        positionOffset = positionOffset - oldLength + newLength;

    ASSERT(positionOffset <= node->length());
    // CharacterNode in VisibleSelection must be Text node, because Comment
    // and ProcessingInstruction node aren't visible.
    return Position(toText(node), positionOffset);
}

void FrameSelection::didUpdateCharacterData(CharacterData* node, unsigned offset, unsigned oldLength, unsigned newLength)
{
    // The fragment check is a performance optimization. See http://trac.webkit.org/changeset/30062.
    if (isNone() || !node || !node->inDocument())
        return;

    Position base = updatePositionAfterAdoptingTextReplacement(m_selection.base(), node, offset, oldLength, newLength);
    Position extent = updatePositionAfterAdoptingTextReplacement(m_selection.extent(), node, offset, oldLength, newLength);
    Position start = updatePositionAfterAdoptingTextReplacement(m_selection.start(), node, offset, oldLength, newLength);
    Position end = updatePositionAfterAdoptingTextReplacement(m_selection.end(), node, offset, oldLength, newLength);
    updateSelectionIfNeeded(base, extent, start, end);
}

static Position updatePostionAfterAdoptingTextNodesMerged(const Position& position, const Text& oldNode, unsigned offset)
{
    if (!position.anchorNode() || position.anchorType() != Position::PositionIsOffsetInAnchor)
        return position;

    ASSERT(position.offsetInContainerNode() >= 0);
    unsigned positionOffset = static_cast<unsigned>(position.offsetInContainerNode());

    if (position.anchorNode() == &oldNode)
        return Position(toText(oldNode.previousSibling()), positionOffset + offset);

    if (position.anchorNode() == oldNode.parentNode() && positionOffset == offset)
        return Position(toText(oldNode.previousSibling()), offset);

    return position;
}

void FrameSelection::didMergeTextNodes(const Text& oldNode, unsigned offset)
{
    if (isNone() || !oldNode.inDocument())
        return;
    Position base = updatePostionAfterAdoptingTextNodesMerged(m_selection.base(), oldNode, offset);
    Position extent = updatePostionAfterAdoptingTextNodesMerged(m_selection.extent(), oldNode, offset);
    Position start = updatePostionAfterAdoptingTextNodesMerged(m_selection.start(), oldNode, offset);
    Position end = updatePostionAfterAdoptingTextNodesMerged(m_selection.end(), oldNode, offset);
    updateSelectionIfNeeded(base, extent, start, end);
}

static Position updatePostionAfterAdoptingTextNodeSplit(const Position& position, const Text& oldNode)
{
    if (!position.anchorNode() || position.anchorNode() != &oldNode || position.anchorType() != Position::PositionIsOffsetInAnchor)
        return position;
    // See: http://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html#Level-2-Range-Mutation
    ASSERT(position.offsetInContainerNode() >= 0);
    unsigned positionOffset = static_cast<unsigned>(position.offsetInContainerNode());
    unsigned oldLength = oldNode.length();
    if (positionOffset <= oldLength)
        return position;
    return Position(toText(oldNode.nextSibling()), positionOffset - oldLength);
}

void FrameSelection::didSplitTextNode(const Text& oldNode)
{
    if (isNone() || !oldNode.inDocument())
        return;
    Position base = updatePostionAfterAdoptingTextNodeSplit(m_selection.base(), oldNode);
    Position extent = updatePostionAfterAdoptingTextNodeSplit(m_selection.extent(), oldNode);
    Position start = updatePostionAfterAdoptingTextNodeSplit(m_selection.start(), oldNode);
    Position end = updatePostionAfterAdoptingTextNodeSplit(m_selection.end(), oldNode);
    updateSelectionIfNeeded(base, extent, start, end);
}

void FrameSelection::updateSelectionIfNeeded(const Position& base, const Position& extent, const Position& start, const Position& end)
{
    if (base == m_selection.base() && extent == m_selection.extent() && start == m_selection.start() && end == m_selection.end())
        return;
    VisibleSelection newSelection;
    newSelection.setWithoutValidation(base, extent);
    m_frame->document()->updateLayout();
    setSelection(newSelection, DoNotSetFocus);
}

TextDirection FrameSelection::directionOfEnclosingBlock()
{
    return WebCore::directionOfEnclosingBlock(m_selection.extent());
}

TextDirection FrameSelection::directionOfSelection()
{
    InlineBox* startBox = 0;
    InlineBox* endBox = 0;
    int unusedOffset;
    // Cache the VisiblePositions because visibleStart() and visibleEnd()
    // can cause layout, which has the potential to invalidate lineboxes.
    VisiblePosition startPosition = m_selection.visibleStart();
    VisiblePosition endPosition = m_selection.visibleEnd();
    if (startPosition.isNotNull())
        startPosition.getInlineBoxAndOffset(startBox, unusedOffset);
    if (endPosition.isNotNull())
        endPosition.getInlineBoxAndOffset(endBox, unusedOffset);
    if (startBox && endBox && startBox->direction() == endBox->direction())
        return startBox->direction();

    return directionOfEnclosingBlock();
}

void FrameSelection::didChangeFocus()
{
    // Hits in virtual/gpu/compositedscrolling/scrollbars/scrollbar-miss-mousemove-disabled.html
    DisableCompositingQueryAsserts disabler;
    updateAppearance();
}

void FrameSelection::willBeModified(EAlteration alter, SelectionDirection direction)
{
    if (alter != AlterationExtend)
        return;

    Position start = m_selection.start();
    Position end = m_selection.end();

    bool baseIsStart = true;

    if (m_selection.isDirectional()) {
        // Make base and extent match start and end so we extend the user-visible selection.
        // This only matters for cases where base and extend point to different positions than
        // start and end (e.g. after a double-click to select a word).
        if (m_selection.isBaseFirst())
            baseIsStart = true;
        else
            baseIsStart = false;
    } else {
        switch (direction) {
        case DirectionRight:
            if (directionOfSelection() == LTR)
                baseIsStart = true;
            else
                baseIsStart = false;
            break;
        case DirectionForward:
            baseIsStart = true;
            break;
        case DirectionLeft:
            if (directionOfSelection() == LTR)
                baseIsStart = false;
            else
                baseIsStart = true;
            break;
        case DirectionBackward:
            baseIsStart = false;
            break;
        }
    }
    if (baseIsStart) {
        m_selection.setBase(start);
        m_selection.setExtent(end);
    } else {
        m_selection.setBase(end);
        m_selection.setExtent(start);
    }
}

VisiblePosition FrameSelection::positionForPlatform(bool isGetStart) const
{
    Settings* settings = m_frame ? m_frame->settings() : 0;
    if (settings && settings->editingBehaviorType() == EditingMacBehavior)
        return isGetStart ? m_selection.visibleStart() : m_selection.visibleEnd();
    // Linux and Windows always extend selections from the extent endpoint.
    // FIXME: VisibleSelection should be fixed to ensure as an invariant that
    // base/extent always point to the same nodes as start/end, but which points
    // to which depends on the value of isBaseFirst. Then this can be changed
    // to just return m_sel.extent().
    return m_selection.isBaseFirst() ? m_selection.visibleEnd() : m_selection.visibleStart();
}

VisiblePosition FrameSelection::startForPlatform() const
{
    return positionForPlatform(true);
}

VisiblePosition FrameSelection::endForPlatform() const
{
    return positionForPlatform(false);
}

VisiblePosition FrameSelection::nextWordPositionForPlatform(const VisiblePosition &originalPosition)
{
    VisiblePosition positionAfterCurrentWord = nextWordPosition(originalPosition);

    if (m_frame && m_frame->editor().behavior().shouldSkipSpaceWhenMovingRight()) {
        // In order to skip spaces when moving right, we advance one
        // word further and then move one word back. Given the
        // semantics of previousWordPosition() this will put us at the
        // beginning of the word following.
        VisiblePosition positionAfterSpacingAndFollowingWord = nextWordPosition(positionAfterCurrentWord);
        if (positionAfterSpacingAndFollowingWord.isNotNull() && positionAfterSpacingAndFollowingWord != positionAfterCurrentWord)
            positionAfterCurrentWord = previousWordPosition(positionAfterSpacingAndFollowingWord);

        bool movingBackwardsMovedPositionToStartOfCurrentWord = positionAfterCurrentWord == previousWordPosition(nextWordPosition(originalPosition));
        if (movingBackwardsMovedPositionToStartOfCurrentWord)
            positionAfterCurrentWord = positionAfterSpacingAndFollowingWord;
    }
    return positionAfterCurrentWord;
}

static void adjustPositionForUserSelectAll(VisiblePosition& pos, bool isForward)
{
    if (Node* rootUserSelectAll = Position::rootUserSelectAllForNode(pos.deepEquivalent().anchorNode()))
        pos = VisiblePosition(isForward ? positionAfterNode(rootUserSelectAll).downstream(CanCrossEditingBoundary) : positionBeforeNode(rootUserSelectAll).upstream(CanCrossEditingBoundary));
}

VisiblePosition FrameSelection::modifyExtendingRight(TextGranularity granularity)
{
    VisiblePosition pos(m_selection.extent(), m_selection.affinity());

    // The difference between modifyExtendingRight and modifyExtendingForward is:
    // modifyExtendingForward always extends forward logically.
    // modifyExtendingRight behaves the same as modifyExtendingForward except for extending character or word,
    // it extends forward logically if the enclosing block is LTR direction,
    // but it extends backward logically if the enclosing block is RTL direction.
    switch (granularity) {
    case CharacterGranularity:
        if (directionOfEnclosingBlock() == LTR)
            pos = pos.next(CanSkipOverEditingBoundary);
        else
            pos = pos.previous(CanSkipOverEditingBoundary);
        break;
    case WordGranularity:
        if (directionOfEnclosingBlock() == LTR)
            pos = nextWordPositionForPlatform(pos);
        else
            pos = previousWordPosition(pos);
        break;
    case LineBoundary:
        if (directionOfEnclosingBlock() == LTR)
            pos = modifyExtendingForward(granularity);
        else
            pos = modifyExtendingBackward(granularity);
        break;
    case SentenceGranularity:
    case LineGranularity:
    case ParagraphGranularity:
    case SentenceBoundary:
    case ParagraphBoundary:
    case DocumentBoundary:
        // FIXME: implement all of the above?
        pos = modifyExtendingForward(granularity);
        break;
    }
    adjustPositionForUserSelectAll(pos, directionOfEnclosingBlock() == LTR);
    return pos;
}

VisiblePosition FrameSelection::modifyExtendingForward(TextGranularity granularity)
{
    VisiblePosition pos(m_selection.extent(), m_selection.affinity());
    switch (granularity) {
    case CharacterGranularity:
        pos = pos.next(CanSkipOverEditingBoundary);
        break;
    case WordGranularity:
        pos = nextWordPositionForPlatform(pos);
        break;
    case SentenceGranularity:
        pos = nextSentencePosition(pos);
        break;
    case LineGranularity:
        pos = nextLinePosition(pos, lineDirectionPointForBlockDirectionNavigation(EXTENT));
        break;
    case ParagraphGranularity:
        pos = nextParagraphPosition(pos, lineDirectionPointForBlockDirectionNavigation(EXTENT));
        break;
    case SentenceBoundary:
        pos = endOfSentence(endForPlatform());
        break;
    case LineBoundary:
        pos = logicalEndOfLine(endForPlatform());
        break;
    case ParagraphBoundary:
        pos = endOfParagraph(endForPlatform());
        break;
    case DocumentBoundary:
        pos = endForPlatform();
        if (isEditablePosition(pos.deepEquivalent()))
            pos = endOfEditableContent(pos);
        else
            pos = endOfDocument(pos);
        break;
    }
    adjustPositionForUserSelectAll(pos, directionOfEnclosingBlock() == LTR);
    return pos;
}

VisiblePosition FrameSelection::modifyMovingRight(TextGranularity granularity)
{
    VisiblePosition pos;
    switch (granularity) {
    case CharacterGranularity:
        if (isRange()) {
            if (directionOfSelection() == LTR)
                pos = VisiblePosition(m_selection.end(), m_selection.affinity());
            else
                pos = VisiblePosition(m_selection.start(), m_selection.affinity());
        } else
            pos = VisiblePosition(m_selection.extent(), m_selection.affinity()).right(true);
        break;
    case WordGranularity: {
        bool skipsSpaceWhenMovingRight = m_frame && m_frame->editor().behavior().shouldSkipSpaceWhenMovingRight();
        pos = rightWordPosition(VisiblePosition(m_selection.extent(), m_selection.affinity()), skipsSpaceWhenMovingRight);
        break;
    }
    case SentenceGranularity:
    case LineGranularity:
    case ParagraphGranularity:
    case SentenceBoundary:
    case ParagraphBoundary:
    case DocumentBoundary:
        // FIXME: Implement all of the above.
        pos = modifyMovingForward(granularity);
        break;
    case LineBoundary:
        pos = rightBoundaryOfLine(startForPlatform(), directionOfEnclosingBlock());
        break;
    }
    return pos;
}

VisiblePosition FrameSelection::modifyMovingForward(TextGranularity granularity)
{
    VisiblePosition pos;
    // FIXME: Stay in editable content for the less common granularities.
    switch (granularity) {
    case CharacterGranularity:
        if (isRange())
            pos = VisiblePosition(m_selection.end(), m_selection.affinity());
        else
            pos = VisiblePosition(m_selection.extent(), m_selection.affinity()).next(CanSkipOverEditingBoundary);
        break;
    case WordGranularity:
        pos = nextWordPositionForPlatform(VisiblePosition(m_selection.extent(), m_selection.affinity()));
        break;
    case SentenceGranularity:
        pos = nextSentencePosition(VisiblePosition(m_selection.extent(), m_selection.affinity()));
        break;
    case LineGranularity: {
        // down-arrowing from a range selection that ends at the start of a line needs
        // to leave the selection at that line start (no need to call nextLinePosition!)
        pos = endForPlatform();
        if (!isRange() || !isStartOfLine(pos))
            pos = nextLinePosition(pos, lineDirectionPointForBlockDirectionNavigation(START));
        break;
    }
    case ParagraphGranularity:
        pos = nextParagraphPosition(endForPlatform(), lineDirectionPointForBlockDirectionNavigation(START));
        break;
    case SentenceBoundary:
        pos = endOfSentence(endForPlatform());
        break;
    case LineBoundary:
        pos = logicalEndOfLine(endForPlatform());
        break;
    case ParagraphBoundary:
        pos = endOfParagraph(endForPlatform());
        break;
    case DocumentBoundary:
        pos = endForPlatform();
        if (isEditablePosition(pos.deepEquivalent()))
            pos = endOfEditableContent(pos);
        else
            pos = endOfDocument(pos);
        break;
    }
    return pos;
}

VisiblePosition FrameSelection::modifyExtendingLeft(TextGranularity granularity)
{
    VisiblePosition pos(m_selection.extent(), m_selection.affinity());

    // The difference between modifyExtendingLeft and modifyExtendingBackward is:
    // modifyExtendingBackward always extends backward logically.
    // modifyExtendingLeft behaves the same as modifyExtendingBackward except for extending character or word,
    // it extends backward logically if the enclosing block is LTR direction,
    // but it extends forward logically if the enclosing block is RTL direction.
    switch (granularity) {
    case CharacterGranularity:
        if (directionOfEnclosingBlock() == LTR)
            pos = pos.previous(CanSkipOverEditingBoundary);
        else
            pos = pos.next(CanSkipOverEditingBoundary);
        break;
    case WordGranularity:
        if (directionOfEnclosingBlock() == LTR)
            pos = previousWordPosition(pos);
        else
            pos = nextWordPositionForPlatform(pos);
        break;
    case LineBoundary:
        if (directionOfEnclosingBlock() == LTR)
            pos = modifyExtendingBackward(granularity);
        else
            pos = modifyExtendingForward(granularity);
        break;
    case SentenceGranularity:
    case LineGranularity:
    case ParagraphGranularity:
    case SentenceBoundary:
    case ParagraphBoundary:
    case DocumentBoundary:
        pos = modifyExtendingBackward(granularity);
        break;
    }
    adjustPositionForUserSelectAll(pos, !(directionOfEnclosingBlock() == LTR));
    return pos;
}

VisiblePosition FrameSelection::modifyExtendingBackward(TextGranularity granularity)
{
    VisiblePosition pos(m_selection.extent(), m_selection.affinity());

    // Extending a selection backward by word or character from just after a table selects
    // the table.  This "makes sense" from the user perspective, esp. when deleting.
    // It was done here instead of in VisiblePosition because we want VPs to iterate
    // over everything.
    switch (granularity) {
    case CharacterGranularity:
        pos = pos.previous(CanSkipOverEditingBoundary);
        break;
    case WordGranularity:
        pos = previousWordPosition(pos);
        break;
    case SentenceGranularity:
        pos = previousSentencePosition(pos);
        break;
    case LineGranularity:
        pos = previousLinePosition(pos, lineDirectionPointForBlockDirectionNavigation(EXTENT));
        break;
    case ParagraphGranularity:
        pos = previousParagraphPosition(pos, lineDirectionPointForBlockDirectionNavigation(EXTENT));
        break;
    case SentenceBoundary:
        pos = startOfSentence(startForPlatform());
        break;
    case LineBoundary:
        pos = logicalStartOfLine(startForPlatform());
        break;
    case ParagraphBoundary:
        pos = startOfParagraph(startForPlatform());
        break;
    case DocumentBoundary:
        pos = startForPlatform();
        if (isEditablePosition(pos.deepEquivalent()))
            pos = startOfEditableContent(pos);
        else
            pos = startOfDocument(pos);
        break;
    }
    adjustPositionForUserSelectAll(pos, !(directionOfEnclosingBlock() == LTR));
    return pos;
}

VisiblePosition FrameSelection::modifyMovingLeft(TextGranularity granularity)
{
    VisiblePosition pos;
    switch (granularity) {
    case CharacterGranularity:
        if (isRange())
            if (directionOfSelection() == LTR)
                pos = VisiblePosition(m_selection.start(), m_selection.affinity());
            else
                pos = VisiblePosition(m_selection.end(), m_selection.affinity());
        else
            pos = VisiblePosition(m_selection.extent(), m_selection.affinity()).left(true);
        break;
    case WordGranularity: {
        bool skipsSpaceWhenMovingRight = m_frame && m_frame->editor().behavior().shouldSkipSpaceWhenMovingRight();
        pos = leftWordPosition(VisiblePosition(m_selection.extent(), m_selection.affinity()), skipsSpaceWhenMovingRight);
        break;
    }
    case SentenceGranularity:
    case LineGranularity:
    case ParagraphGranularity:
    case SentenceBoundary:
    case ParagraphBoundary:
    case DocumentBoundary:
        // FIXME: Implement all of the above.
        pos = modifyMovingBackward(granularity);
        break;
    case LineBoundary:
        pos = leftBoundaryOfLine(startForPlatform(), directionOfEnclosingBlock());
        break;
    }
    return pos;
}

VisiblePosition FrameSelection::modifyMovingBackward(TextGranularity granularity)
{
    VisiblePosition pos;
    switch (granularity) {
    case CharacterGranularity:
        if (isRange())
            pos = VisiblePosition(m_selection.start(), m_selection.affinity());
        else
            pos = VisiblePosition(m_selection.extent(), m_selection.affinity()).previous(CanSkipOverEditingBoundary);
        break;
    case WordGranularity:
        pos = previousWordPosition(VisiblePosition(m_selection.extent(), m_selection.affinity()));
        break;
    case SentenceGranularity:
        pos = previousSentencePosition(VisiblePosition(m_selection.extent(), m_selection.affinity()));
        break;
    case LineGranularity:
        pos = previousLinePosition(startForPlatform(), lineDirectionPointForBlockDirectionNavigation(START));
        break;
    case ParagraphGranularity:
        pos = previousParagraphPosition(startForPlatform(), lineDirectionPointForBlockDirectionNavigation(START));
        break;
    case SentenceBoundary:
        pos = startOfSentence(startForPlatform());
        break;
    case LineBoundary:
        pos = logicalStartOfLine(startForPlatform());
        break;
    case ParagraphBoundary:
        pos = startOfParagraph(startForPlatform());
        break;
    case DocumentBoundary:
        pos = startForPlatform();
        if (isEditablePosition(pos.deepEquivalent()))
            pos = startOfEditableContent(pos);
        else
            pos = startOfDocument(pos);
        break;
    }
    return pos;
}

static bool isBoundary(TextGranularity granularity)
{
    return granularity == LineBoundary || granularity == ParagraphBoundary || granularity == DocumentBoundary;
}

bool FrameSelection::modify(EAlteration alter, SelectionDirection direction, TextGranularity granularity, EUserTriggered userTriggered)
{
    if (userTriggered == UserTriggered) {
        FrameSelection trialFrameSelection;
        trialFrameSelection.setSelection(m_selection);
        trialFrameSelection.modify(alter, direction, granularity, NotUserTriggered);

        if (trialFrameSelection.selection().isRange() && m_selection.isCaret() && !dispatchSelectStart())
            return false;
    }

    willBeModified(alter, direction);

    bool wasRange = m_selection.isRange();
    VisiblePosition originalStartPosition = m_selection.visibleStart();
    VisiblePosition position;
    switch (direction) {
    case DirectionRight:
        if (alter == AlterationMove)
            position = modifyMovingRight(granularity);
        else
            position = modifyExtendingRight(granularity);
        break;
    case DirectionForward:
        if (alter == AlterationExtend)
            position = modifyExtendingForward(granularity);
        else
            position = modifyMovingForward(granularity);
        break;
    case DirectionLeft:
        if (alter == AlterationMove)
            position = modifyMovingLeft(granularity);
        else
            position = modifyExtendingLeft(granularity);
        break;
    case DirectionBackward:
        if (alter == AlterationExtend)
            position = modifyExtendingBackward(granularity);
        else
            position = modifyMovingBackward(granularity);
        break;
    }

    if (position.isNull())
        return false;

    if (isSpatialNavigationEnabled(m_frame))
        if (!wasRange && alter == AlterationMove && position == originalStartPosition)
            return false;

    // Some of the above operations set an xPosForVerticalArrowNavigation.
    // Setting a selection will clear it, so save it to possibly restore later.
    // Note: the START position type is arbitrary because it is unused, it would be
    // the requested position type if there were no xPosForVerticalArrowNavigation set.
    LayoutUnit x = lineDirectionPointForBlockDirectionNavigation(START);
    m_selection.setIsDirectional(shouldAlwaysUseDirectionalSelection(m_frame) || alter == AlterationExtend);

    switch (alter) {
    case AlterationMove:
        moveTo(position, userTriggered);
        break;
    case AlterationExtend:

        if (!m_selection.isCaret()
            && (granularity == WordGranularity || granularity == ParagraphGranularity || granularity == LineGranularity)
            && m_frame && !m_frame->editor().behavior().shouldExtendSelectionByWordOrLineAcrossCaret()) {
            // Don't let the selection go across the base position directly. Needed to match mac
            // behavior when, for instance, word-selecting backwards starting with the caret in
            // the middle of a word and then word-selecting forward, leaving the caret in the
            // same place where it was, instead of directly selecting to the end of the word.
            VisibleSelection newSelection = m_selection;
            newSelection.setExtent(position);
            if (m_selection.isBaseFirst() != newSelection.isBaseFirst())
                position = m_selection.visibleBase();
        }

        // Standard Mac behavior when extending to a boundary is grow the selection rather than leaving the
        // base in place and moving the extent. Matches NSTextView.
        if (!m_frame || !m_frame->editor().behavior().shouldAlwaysGrowSelectionWhenExtendingToBoundary() || m_selection.isCaret() || !isBoundary(granularity))
            setExtent(position, userTriggered);
        else {
            TextDirection textDirection = directionOfEnclosingBlock();
            if (direction == DirectionForward || (textDirection == LTR && direction == DirectionRight) || (textDirection == RTL && direction == DirectionLeft))
                setEnd(position, userTriggered);
            else
                setStart(position, userTriggered);
        }
        break;
    }

    if (granularity == LineGranularity || granularity == ParagraphGranularity)
        m_xPosForVerticalArrowNavigation = x;

    if (userTriggered == UserTriggered)
        m_granularity = CharacterGranularity;

    setCaretRectNeedsUpdate();

    return true;
}

// FIXME: Maybe baseline would be better?
static bool absoluteCaretY(const VisiblePosition &c, int &y)
{
    IntRect rect = c.absoluteCaretBounds();
    if (rect.isEmpty())
        return false;
    y = rect.y() + rect.height() / 2;
    return true;
}

bool FrameSelection::modify(EAlteration alter, unsigned verticalDistance, VerticalDirection direction, EUserTriggered userTriggered, CursorAlignOnScroll align)
{
    if (!verticalDistance)
        return false;

    if (userTriggered == UserTriggered) {
        FrameSelection trialFrameSelection;
        trialFrameSelection.setSelection(m_selection);
        trialFrameSelection.modify(alter, verticalDistance, direction, NotUserTriggered);
    }

    willBeModified(alter, direction == DirectionUp ? DirectionBackward : DirectionForward);

    VisiblePosition pos;
    LayoutUnit xPos = 0;
    switch (alter) {
    case AlterationMove:
        pos = VisiblePosition(direction == DirectionUp ? m_selection.start() : m_selection.end(), m_selection.affinity());
        xPos = lineDirectionPointForBlockDirectionNavigation(direction == DirectionUp ? START : END);
        m_selection.setAffinity(direction == DirectionUp ? UPSTREAM : DOWNSTREAM);
        break;
    case AlterationExtend:
        pos = VisiblePosition(m_selection.extent(), m_selection.affinity());
        xPos = lineDirectionPointForBlockDirectionNavigation(EXTENT);
        m_selection.setAffinity(DOWNSTREAM);
        break;
    }

    int startY;
    if (!absoluteCaretY(pos, startY))
        return false;
    if (direction == DirectionUp)
        startY = -startY;
    int lastY = startY;

    VisiblePosition result;
    VisiblePosition next;
    for (VisiblePosition p = pos; ; p = next) {
        if (direction == DirectionUp)
            next = previousLinePosition(p, xPos);
        else
            next = nextLinePosition(p, xPos);

        if (next.isNull() || next == p)
            break;
        int nextY;
        if (!absoluteCaretY(next, nextY))
            break;
        if (direction == DirectionUp)
            nextY = -nextY;
        if (nextY - startY > static_cast<int>(verticalDistance))
            break;
        if (nextY >= lastY) {
            lastY = nextY;
            result = next;
        }
    }

    if (result.isNull())
        return false;

    switch (alter) {
    case AlterationMove:
        moveTo(result, userTriggered, align);
        break;
    case AlterationExtend:
        setExtent(result, userTriggered);
        break;
    }

    if (userTriggered == UserTriggered)
        m_granularity = CharacterGranularity;

    m_selection.setIsDirectional(shouldAlwaysUseDirectionalSelection(m_frame) || alter == AlterationExtend);

    return true;
}

LayoutUnit FrameSelection::lineDirectionPointForBlockDirectionNavigation(EPositionType type)
{
    LayoutUnit x = 0;

    if (isNone())
        return x;

    Position pos;
    switch (type) {
    case START:
        pos = m_selection.start();
        break;
    case END:
        pos = m_selection.end();
        break;
    case BASE:
        pos = m_selection.base();
        break;
    case EXTENT:
        pos = m_selection.extent();
        break;
    }

    LocalFrame* frame = pos.document()->frame();
    if (!frame)
        return x;

    if (m_xPosForVerticalArrowNavigation == NoXPosForVerticalArrowNavigation()) {
        VisiblePosition visiblePosition(pos, m_selection.affinity());
        // VisiblePosition creation can fail here if a node containing the selection becomes visibility:hidden
        // after the selection is created and before this function is called.
        x = visiblePosition.isNotNull() ? visiblePosition.lineDirectionPointForBlockDirectionNavigation() : 0;
        m_xPosForVerticalArrowNavigation = x;
    } else
        x = m_xPosForVerticalArrowNavigation;

    return x;
}

void FrameSelection::clear()
{
    m_granularity = CharacterGranularity;
    setSelection(VisibleSelection());
}

void FrameSelection::prepareForDestruction()
{
    m_granularity = CharacterGranularity;

    m_caretBlinkTimer.stop();

    RenderView* view = m_frame->contentRenderer();
    if (view)
        view->clearSelection();

    setSelection(VisibleSelection(), CloseTyping | ClearTypingStyle | DoNotUpdateAppearance);
    m_previousCaretNode.clear();
}

void FrameSelection::setStart(const VisiblePosition &pos, EUserTriggered trigger)
{
    if (m_selection.isBaseFirst())
        setBase(pos, trigger);
    else
        setExtent(pos, trigger);
}

void FrameSelection::setEnd(const VisiblePosition &pos, EUserTriggered trigger)
{
    if (m_selection.isBaseFirst())
        setExtent(pos, trigger);
    else
        setBase(pos, trigger);
}

void FrameSelection::setBase(const VisiblePosition &pos, EUserTriggered userTriggered)
{
    const bool selectionHasDirection = true;
    setSelection(VisibleSelection(pos.deepEquivalent(), m_selection.extent(), pos.affinity(), selectionHasDirection), CloseTyping | ClearTypingStyle | userTriggered);
}

void FrameSelection::setExtent(const VisiblePosition &pos, EUserTriggered userTriggered)
{
    const bool selectionHasDirection = true;
    setSelection(VisibleSelection(m_selection.base(), pos.deepEquivalent(), pos.affinity(), selectionHasDirection), CloseTyping | ClearTypingStyle | userTriggered);
}

RenderObject* FrameSelection::caretRenderer() const
{
    return CaretBase::caretRenderer(m_selection.start().deprecatedNode());
}

static bool isNonOrphanedCaret(const VisibleSelection& selection)
{
    return selection.isCaret() && !selection.start().isOrphan() && !selection.end().isOrphan();
}

LayoutRect FrameSelection::localCaretRect()
{
    if (shouldUpdateCaretRect()) {
        if (!isNonOrphanedCaret(m_selection))
            clearCaretRect();
        else if (updateCaretRect(m_frame->document(), VisiblePosition(m_selection.start(), m_selection.affinity())))
            m_absCaretBoundsDirty = true;
    }

    return localCaretRectWithoutUpdate();
}

IntRect FrameSelection::absoluteCaretBounds()
{
    recomputeCaretRect();
    return m_absCaretBounds;
}

bool FrameSelection::recomputeCaretRect()
{
    if (!shouldUpdateCaretRect())
        return false;

    if (!m_frame || !m_frame->document()->view())
        return false;

    LayoutRect oldRect = localCaretRectWithoutUpdate();
    LayoutRect newRect = localCaretRect();
    if (oldRect == newRect && !m_absCaretBoundsDirty)
        return false;

    IntRect oldAbsCaretBounds = m_absCaretBounds;
    m_absCaretBounds = absoluteBoundsForLocalRect(m_selection.start().deprecatedNode(), localCaretRectWithoutUpdate());
    m_absCaretBoundsDirty = false;

    if (oldAbsCaretBounds == m_absCaretBounds)
        return false;

    if (RenderView* view = m_frame->document()->renderView()) {
        if (m_previousCaretNode && shouldRepaintCaret(view, m_previousCaretNode->isContentEditable()))
            repaintCaretForLocalRect(m_previousCaretNode.get(), oldRect);
        Node* node = m_selection.start().deprecatedNode();
        m_previousCaretNode = node;
        if (shouldRepaintCaret(view, isContentEditable()))
            repaintCaretForLocalRect(node, newRect);
    }

    return true;
}

void FrameSelection::invalidateCaretRect()
{
    if (!isCaret())
        return;

    CaretBase::invalidateCaretRect(m_selection.start().deprecatedNode(), recomputeCaretRect());
}

void FrameSelection::paintCaret(GraphicsContext* context, const LayoutPoint& paintOffset, const LayoutRect& clipRect)
{
    if (m_selection.isCaret() && m_caretPaint)
        CaretBase::paintCaret(m_selection.start().deprecatedNode(), context, paintOffset, clipRect);
}

bool FrameSelection::contains(const LayoutPoint& point)
{
    Document* document = m_frame->document();

    // Treat a collapsed selection like no selection.
    if (!isRange())
        return false;
    if (!document->renderView())
        return false;

    HitTestRequest request(HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::ConfusingAndOftenMisusedDisallowShadowContent);
    HitTestResult result(point);
    document->renderView()->hitTest(request, result);
    Node* innerNode = result.innerNode();
    if (!innerNode || !innerNode->renderer())
        return false;

    VisiblePosition visiblePos(innerNode->renderer()->positionForPoint(result.localPoint()));
    if (visiblePos.isNull())
        return false;

    if (m_selection.visibleStart().isNull() || m_selection.visibleEnd().isNull())
        return false;

    Position start(m_selection.visibleStart().deepEquivalent());
    Position end(m_selection.visibleEnd().deepEquivalent());
    Position p(visiblePos.deepEquivalent());

    return comparePositions(start, p) <= 0 && comparePositions(p, end) <= 0;
}

// Workaround for the fact that it's hard to delete a frame.
// Call this after doing user-triggered selections to make it easy to delete the frame you entirely selected.
// Can't do this implicitly as part of every setSelection call because in some contexts it might not be good
// for the focus to move to another frame. So instead we call it from places where we are selecting with the
// mouse or the keyboard after setting the selection.
void FrameSelection::selectFrameElementInParentIfFullySelected()
{
    // Find the parent frame; if there is none, then we have nothing to do.
    LocalFrame* parent = m_frame->tree().parent();
    if (!parent)
        return;
    Page* page = m_frame->page();
    if (!page)
        return;

    // Check if the selection contains the entire frame contents; if not, then there is nothing to do.
    if (!isRange())
        return;
    if (!isStartOfDocument(selection().visibleStart()))
        return;
    if (!isEndOfDocument(selection().visibleEnd()))
        return;

    // Get to the <iframe> or <frame> (or even <object>) element in the parent frame.
    Element* ownerElement = m_frame->ownerElement();
    if (!ownerElement)
        return;
    ContainerNode* ownerElementParent = ownerElement->parentNode();
    if (!ownerElementParent)
        return;

    // This method's purpose is it to make it easier to select iframes (in order to delete them).  Don't do anything if the iframe isn't deletable.
    if (!ownerElementParent->rendererIsEditable())
        return;

    // Create compute positions before and after the element.
    unsigned ownerElementNodeIndex = ownerElement->nodeIndex();
    VisiblePosition beforeOwnerElement(VisiblePosition(Position(ownerElementParent, ownerElementNodeIndex, Position::PositionIsOffsetInAnchor)));
    VisiblePosition afterOwnerElement(VisiblePosition(Position(ownerElementParent, ownerElementNodeIndex + 1, Position::PositionIsOffsetInAnchor), VP_UPSTREAM_IF_POSSIBLE));

    // Focus on the parent frame, and then select from before this element to after.
    VisibleSelection newSelection(beforeOwnerElement, afterOwnerElement);
    page->focusController().setFocusedFrame(parent);
    parent->selection().setSelection(newSelection);
}

void FrameSelection::selectAll()
{
    Document* document = m_frame->document();

    if (isHTMLSelectElement(document->focusedElement())) {
        HTMLSelectElement* selectElement = toHTMLSelectElement(document->focusedElement());
        if (selectElement->canSelectAll()) {
            selectElement->selectAll();
            return;
        }
    }

    RefPtr<Node> root = nullptr;
    Node* selectStartTarget = 0;
    if (isContentEditable()) {
        root = highestEditableRoot(m_selection.start());
        if (Node* shadowRoot = m_selection.nonBoundaryShadowTreeRootNode())
            selectStartTarget = shadowRoot->shadowHost();
        else
            selectStartTarget = root.get();
    } else {
        root = m_selection.nonBoundaryShadowTreeRootNode();
        if (root)
            selectStartTarget = root->shadowHost();
        else {
            root = document->documentElement();
            selectStartTarget = document->body();
        }
    }
    if (!root)
        return;

    if (selectStartTarget && !selectStartTarget->dispatchEvent(Event::createCancelableBubble(EventTypeNames::selectstart)))
        return;

    VisibleSelection newSelection(VisibleSelection::selectionFromContentsOfNode(root.get()));
    setSelection(newSelection);
    selectFrameElementInParentIfFullySelected();
    notifyRendererOfSelectionChange(UserTriggered);
}

bool FrameSelection::setSelectedRange(Range* range, EAffinity affinity, SetSelectionOptions options)
{
    if (!range || !range->startContainer() || !range->endContainer())
        return false;
    ASSERT(range->startContainer()->document() == range->endContainer()->document());

    m_frame->document()->updateLayoutIgnorePendingStylesheets();

    // Non-collapsed ranges are not allowed to start at the end of a line that is wrapped,
    // they start at the beginning of the next line instead
    TrackExceptionState exceptionState;
    bool collapsed = range->collapsed(exceptionState);
    if (exceptionState.hadException())
        return false;

    m_logicalRange = nullptr;
    stopObservingVisibleSelectionChangeIfNecessary();

    // FIXME: Can we provide extentAffinity?
    VisiblePosition visibleStart(range->startPosition(), collapsed ? affinity : DOWNSTREAM);
    VisiblePosition visibleEnd(range->endPosition(), SEL_DEFAULT_AFFINITY);
    setSelection(VisibleSelection(visibleStart, visibleEnd), options);

    m_logicalRange = range->cloneRange(ASSERT_NO_EXCEPTION);
    startObservingVisibleSelectionChange();

    return true;
}

PassRefPtrWillBeRawPtr<Range> FrameSelection::firstRange() const
{
    if (m_logicalRange)
        return m_logicalRange->cloneRange(ASSERT_NO_EXCEPTION);
    return m_selection.firstRange();
}

bool FrameSelection::isInPasswordField() const
{
    HTMLTextFormControlElement* textControl = enclosingTextFormControl(start());
    return isHTMLInputElement(textControl) && toHTMLInputElement(textControl)->isPasswordField();
}

void FrameSelection::notifyAccessibilityForSelectionChange()
{
    if (m_selection.start().isNotNull() && m_selection.end().isNotNull()) {
        if (AXObjectCache* cache = m_frame->document()->existingAXObjectCache())
            cache->selectionChanged(m_selection.start().containerNode());
    }
}

void FrameSelection::focusedOrActiveStateChanged()
{
    bool activeAndFocused = isFocusedAndActive();

    RefPtr<Document> document = m_frame->document();
    document->updateRenderTreeIfNeeded();

    // Because RenderObject::selectionBackgroundColor() and
    // RenderObject::selectionForegroundColor() check if the frame is active,
    // we have to update places those colors were painted.
    if (RenderView* view = document->renderView())
        view->repaintSelection();

    // Caret appears in the active frame.
    if (activeAndFocused)
        setSelectionFromNone();
    else
        m_frame->spellChecker().spellCheckAfterBlur();
    setCaretVisibility(activeAndFocused ? Visible : Hidden);

    // Update for caps lock state
    m_frame->eventHandler().capsLockStateMayHaveChanged();

    // We may have lost active status even though the focusElement hasn't changed
    // give the element a chance to recalc style if its affected by focus.
    if (Element* element = document->focusedElement())
        element->focusStateChanged();

    // Secure keyboard entry is set by the active frame.
    if (document->useSecureKeyboardEntryWhenActive())
        setUseSecureKeyboardEntry(activeAndFocused);
}

void FrameSelection::pageActivationChanged()
{
    focusedOrActiveStateChanged();
}

void FrameSelection::updateSecureKeyboardEntryIfActive()
{
    if (m_frame->document() && isFocusedAndActive())
        setUseSecureKeyboardEntry(m_frame->document()->useSecureKeyboardEntryWhenActive());
}

void FrameSelection::setUseSecureKeyboardEntry(bool enable)
{
    if (enable)
        enableSecureTextInput();
    else
        disableSecureTextInput();
}

void FrameSelection::setFocused(bool flag)
{
    if (m_focused == flag)
        return;
    m_focused = flag;

    focusedOrActiveStateChanged();
}

bool FrameSelection::isFocusedAndActive() const
{
    return m_focused && m_frame->page() && m_frame->page()->focusController().isActive();
}

inline static bool shouldStopBlinkingDueToTypingCommand(LocalFrame* frame)
{
    return frame->editor().lastEditCommand() && frame->editor().lastEditCommand()->shouldStopCaretBlinking();
}

void FrameSelection::updateAppearance()
{
    // Paint a block cursor instead of a caret in overtype mode unless the caret is at the end of a line (in this case
    // the FrameSelection will paint a blinking caret as usual).
    VisiblePosition forwardPosition;
    if (m_shouldShowBlockCursor && m_selection.isCaret()) {
        forwardPosition = modifyExtendingForward(CharacterGranularity);
        m_caretPaint = forwardPosition.isNull();
    }

    bool caretRectChangedOrCleared = recomputeCaretRect();
    bool shouldBlink = shouldBlinkCaret() && forwardPosition.isNull();

    // If the caret moved, stop the blink timer so we can restart with a
    // black caret in the new location.
    if (caretRectChangedOrCleared || !shouldBlink || shouldStopBlinkingDueToTypingCommand(m_frame)) {
        m_caretBlinkTimer.stop();
        if (!shouldBlink && m_caretPaint) {
            m_caretPaint = false;
            invalidateCaretRect();
        }
    }

    // Start blinking with a black caret. Be sure not to restart if we're
    // already blinking in the right location.
    if (shouldBlink && !m_caretBlinkTimer.isActive()) {
        if (double blinkInterval = RenderTheme::theme().caretBlinkInterval())
            m_caretBlinkTimer.startRepeating(blinkInterval, FROM_HERE);

        if (!m_caretPaint) {
            m_caretPaint = true;
            invalidateCaretRect();
        }
    }

    RenderView* view = m_frame->contentRenderer();
    if (!view)
        return;

    // Construct a new VisibleSolution, since m_selection is not necessarily valid, and the following steps
    // assume a valid selection. See <https://bugs.webkit.org/show_bug.cgi?id=69563> and <rdar://problem/10232866>.
    VisibleSelection selection(m_selection.visibleStart(), forwardPosition.isNotNull() ? forwardPosition : m_selection.visibleEnd());

    if (!selection.isRange()) {
        view->clearSelection();
        return;
    }

    // Use the rightmost candidate for the start of the selection, and the leftmost candidate for the end of the selection.
    // Example: foo <a>bar</a>.  Imagine that a line wrap occurs after 'foo', and that 'bar' is selected.   If we pass [foo, 3]
    // as the start of the selection, the selection painting code will think that content on the line containing 'foo' is selected
    // and will fill the gap before 'bar'.
    Position startPos = selection.start();
    Position candidate = startPos.downstream();
    if (candidate.isCandidate())
        startPos = candidate;
    Position endPos = selection.end();
    candidate = endPos.upstream();
    if (candidate.isCandidate())
        endPos = candidate;

    // We can get into a state where the selection endpoints map to the same VisiblePosition when a selection is deleted
    // because we don't yet notify the FrameSelection of text removal.
    if (startPos.isNotNull() && endPos.isNotNull() && selection.visibleStart() != selection.visibleEnd()) {
        RenderObject* startRenderer = startPos.deprecatedNode()->renderer();
        RenderObject* endRenderer = endPos.deprecatedNode()->renderer();
        view->setSelection(startRenderer, startPos.deprecatedEditingOffset(), endRenderer, endPos.deprecatedEditingOffset());
    }
}

void FrameSelection::setCaretVisibility(CaretVisibility visibility)
{
    if (caretVisibility() == visibility)
        return;

    m_frame->document()->updateLayoutIgnorePendingStylesheets();
    if (m_caretPaint) {
        m_caretPaint = false;
        invalidateCaretRect();
    }
    CaretBase::setCaretVisibility(visibility);

    updateAppearance();
}

bool FrameSelection::shouldBlinkCaret() const
{
    if (!caretIsVisible() || !isCaret())
        return false;

    if (m_frame->settings() && m_frame->settings()->caretBrowsingEnabled())
        return false;

    Node* root = rootEditableElement();
    if (!root)
        return false;

    Element* focusedElement = root->document().focusedElement();
    if (!focusedElement)
        return false;

    return focusedElement->containsIncludingShadowDOM(m_selection.start().anchorNode());
}

void FrameSelection::caretBlinkTimerFired(Timer<FrameSelection>*)
{
    ASSERT(caretIsVisible());
    ASSERT(isCaret());
    bool caretPaint = m_caretPaint;
    if (isCaretBlinkingSuspended() && caretPaint)
        return;
    m_caretPaint = !caretPaint;
    invalidateCaretRect();
}

void FrameSelection::notifyRendererOfSelectionChange(EUserTriggered userTriggered)
{
    m_frame->document()->updateRenderTreeIfNeeded();

    if (HTMLTextFormControlElement* textControl = enclosingTextFormControl(start()))
        textControl->selectionChanged(userTriggered == UserTriggered);
}

// Helper function that tells whether a particular node is an element that has an entire
// LocalFrame and FrameView, a <frame>, <iframe>, or <object>.
static bool isFrameElement(const Node* n)
{
    if (!n)
        return false;
    RenderObject* renderer = n->renderer();
    if (!renderer || !renderer->isWidget())
        return false;
    Widget* widget = toRenderWidget(renderer)->widget();
    return widget && widget->isFrameView();
}

void FrameSelection::setFocusedNodeIfNeeded()
{
    if (isNone() || !isFocused())
        return;

    bool caretBrowsing = m_frame->settings() && m_frame->settings()->caretBrowsingEnabled();
    if (caretBrowsing) {
        if (Element* anchor = enclosingAnchorElement(base())) {
            m_frame->page()->focusController().setFocusedElement(anchor, m_frame);
            return;
        }
    }

    if (Element* target = rootEditableElement()) {
        // Walk up the DOM tree to search for a node to focus.
        while (target) {
            // We don't want to set focus on a subframe when selecting in a parent frame,
            // so add the !isFrameElement check here. There's probably a better way to make this
            // work in the long term, but this is the safest fix at this time.
            if (target->isMouseFocusable() && !isFrameElement(target)) {
                m_frame->page()->focusController().setFocusedElement(target, m_frame);
                return;
            }
            target = target->parentOrShadowHostElement();
        }
        m_frame->document()->setFocusedElement(nullptr);
    }

    if (caretBrowsing)
        m_frame->page()->focusController().setFocusedElement(0, m_frame);
}

static String extractSelectedText(const FrameSelection& selection, TextIteratorBehavior behavior)
{
    // We remove '\0' characters because they are not visibly rendered to the user.
    return plainText(selection.toNormalizedRange().get(), behavior).replace(0, "");
}

String FrameSelection::selectedText() const
{
    return extractSelectedText(*this, TextIteratorDefaultBehavior);
}

String FrameSelection::selectedTextForClipboard() const
{
    if (m_frame->settings() && m_frame->settings()->selectionIncludesAltImageText())
        return extractSelectedText(*this, TextIteratorEmitsImageAltText);
    return selectedText();
}

FloatRect FrameSelection::bounds(bool clipToVisibleContent) const
{
    m_frame->document()->updateRenderTreeIfNeeded();

    FrameView* view = m_frame->view();
    RenderView* renderView = m_frame->contentRenderer();

    if (!view || !renderView)
        return FloatRect();

    LayoutRect selectionRect = renderView->selectionBounds(clipToVisibleContent);
    return clipToVisibleContent ? intersection(selectionRect, view->visibleContentRect()) : selectionRect;
}

static inline HTMLFormElement* associatedFormElement(HTMLElement& element)
{
    if (isHTMLFormElement(element))
        return &toHTMLFormElement(element);
    return element.formOwner();
}

// Scans logically forward from "start", including any child frames.
static HTMLFormElement* scanForForm(Node* start)
{
    if (!start)
        return 0;

    HTMLElement* element = start->isHTMLElement() ? toHTMLElement(start) : Traversal<HTMLElement>::next(*start);
    for (; element; element = Traversal<HTMLElement>::next(*element)) {
        if (HTMLFormElement* form = associatedFormElement(*element))
            return form;

        if (isHTMLFrameElementBase(*element)) {
            Node* childDocument = toHTMLFrameElementBase(*element).contentDocument();
            if (HTMLFormElement* frameResult = scanForForm(childDocument))
                return frameResult;
        }
    }
    return 0;
}

// We look for either the form containing the current focus, or for one immediately after it
HTMLFormElement* FrameSelection::currentForm() const
{
    // Start looking either at the active (first responder) node, or where the selection is.
    Node* start = m_frame->document()->focusedElement();
    if (!start)
        start = this->start().deprecatedNode();
    if (!start)
        return 0;

    // Try walking up the node tree to find a form element.
    for (HTMLElement* element = Traversal<HTMLElement>::firstAncestorOrSelf(*start); element; element = Traversal<HTMLElement>::firstAncestor(*element)) {
        if (HTMLFormElement* form = associatedFormElement(*element))
            return form;
    }

    // Try walking forward in the node tree to find a form element.
    return scanForForm(start);
}

void FrameSelection::revealSelection(const ScrollAlignment& alignment, RevealExtentOption revealExtentOption)
{
    LayoutRect rect;

    switch (selectionType()) {
    case NoSelection:
        return;
    case CaretSelection:
        rect = absoluteCaretBounds();
        break;
    case RangeSelection:
        rect = revealExtentOption == RevealExtent ? VisiblePosition(extent()).absoluteCaretBounds() : enclosingIntRect(bounds(false));
        break;
    }

    Position start = this->start();
    ASSERT(start.deprecatedNode());
    if (start.deprecatedNode() && start.deprecatedNode()->renderer()) {
        // FIXME: This code only handles scrolling the startContainer's layer, but
        // the selection rect could intersect more than just that.
        // See <rdar://problem/4799899>.
        if (start.deprecatedNode()->renderer()->scrollRectToVisible(rect, alignment, alignment))
            updateAppearance();
    }
}

void FrameSelection::setSelectionFromNone()
{
    // Put a caret inside the body if the entire frame is editable (either the
    // entire WebView is editable or designMode is on for this document).

    Document* document = m_frame->document();
    bool caretBrowsing = m_frame->settings() && m_frame->settings()->caretBrowsingEnabled();
    if (!isNone() || !(document->rendererIsEditable() || caretBrowsing))
        return;

    Node* node = document->documentElement();
    if (!node)
        return;
    Node* body = isHTMLBodyElement(*node) ? node : Traversal<HTMLBodyElement>::next(*node);
    if (body)
        setSelection(VisibleSelection(firstPositionInOrBeforeNode(body), DOWNSTREAM));
}

bool FrameSelection::dispatchSelectStart()
{
    Node* selectStartTarget = m_selection.extent().containerNode();
    if (!selectStartTarget)
        return true;

    return selectStartTarget->dispatchEvent(Event::createCancelableBubble(EventTypeNames::selectstart));
}

void FrameSelection::setShouldShowBlockCursor(bool shouldShowBlockCursor)
{
    m_shouldShowBlockCursor = shouldShowBlockCursor;

    m_frame->document()->updateLayoutIgnorePendingStylesheets();

    updateAppearance();
}

void FrameSelection::didChangeVisibleSelection()
{
    ASSERT(m_observingVisibleSelection);
    // Invalidate the logical range when the underlying VisibleSelection has changed.
    m_logicalRange = nullptr;
    m_selection.clearChangeObserver();
    m_observingVisibleSelection = false;
}

void FrameSelection::startObservingVisibleSelectionChange()
{
    ASSERT(!m_observingVisibleSelection);
    m_selection.setChangeObserver(*this);
    m_observingVisibleSelection = true;
}

void FrameSelection::stopObservingVisibleSelectionChangeIfNecessary()
{
    if (m_observingVisibleSelection) {
        m_selection.clearChangeObserver();
        m_observingVisibleSelection = false;
    }
}

#ifndef NDEBUG

void FrameSelection::formatForDebugger(char* buffer, unsigned length) const
{
    m_selection.formatForDebugger(buffer, length);
}

void FrameSelection::showTreeForThis() const
{
    m_selection.showTreeForThis();
}

#endif

}

#ifndef NDEBUG

void showTree(const WebCore::FrameSelection& sel)
{
    sel.showTreeForThis();
}

void showTree(const WebCore::FrameSelection* sel)
{
    if (sel)
        sel->showTreeForThis();
}

#endif
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root/Source/core/editing/FrameSelection.cpp

DEFINITIONS
