root/Source/core/page/FocusController.cpp

DEFINITIONS

1. isShadowInsertionPointFocusScopeOwner
2. rootNode
3. owner
4. focusNavigationScopeOf
5. ownedByNonFocusableFocusScopeOwner
6. ownedByShadowHost
7. ownedByIFrame
8. ownedByShadowInsertionPoint
9. dispatchEventsOnWindowAndFocusedNode
10. hasCustomFocusLogic
11. isNonFocusableShadowHost
12. isNonKeyboardFocusableShadowHost
13. isKeyboardFocusableShadowHost
14. isNonFocusableFocusScopeOwner
15. adjustedTabIndex
16. shouldVisit
17. m_containingWindowIsVisible
18. create
19. setFocusedFrame
20. focusedOrMainFrame
21. setFocused
22. findFocusableNodeDecendingDownIntoFrameDocument
23. setInitialFocus
24. advanceFocus
25. advanceFocusInDocumentOrder
26. findFocusableNodeAcrossFocusScope
27. findFocusableNodeRecursively
28. findFocusableNode
29. findNodeWithExactTabIndex
30. nextNodeWithGreaterTabIndex
31. previousNodeWithLowerTabIndex
32. nextFocusableNode
33. previousFocusableNode
34. relinquishesEditingFocus
35. clearSelectionIfNeeded
36. setFocusedElement
37. setActive
38. contentAreaDidShowOrHide
39. setContainingWindowIsVisible
40. updateFocusCandidateIfNeeded
41. findFocusCandidateInContainer
42. advanceFocusDirectionallyInContainer
43. advanceFocusDirectionally

/*
 * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Nuanti Ltd.
 *
 * 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/page/FocusController.h"

#include <limits>
#include "HTMLNames.h"
#include "core/accessibility/AXObjectCache.h"
#include "core/dom/Document.h"
#include "core/dom/Element.h"
#include "core/dom/ElementTraversal.h"
#include "core/dom/NodeTraversal.h"
#include "core/dom/Range.h"
#include "core/dom/shadow/ElementShadow.h"
#include "core/dom/shadow/ShadowRoot.h"
#include "core/editing/Editor.h"
#include "core/editing/FrameSelection.h"
#include "core/editing/htmlediting.h" // For firstPositionInOrBeforeNode
#include "core/events/Event.h"
#include "core/frame/DOMWindow.h"
#include "core/frame/FrameView.h"
#include "core/frame/LocalFrame.h"
#include "core/html/HTMLAreaElement.h"
#include "core/html/HTMLImageElement.h"
#include "core/html/HTMLPlugInElement.h"
#include "core/html/HTMLShadowElement.h"
#include "core/page/Chrome.h"
#include "core/page/ChromeClient.h"
#include "core/page/EventHandler.h"
#include "core/page/FrameTree.h"
#include "core/page/Page.h"
#include "core/frame/Settings.h"
#include "core/page/SpatialNavigation.h"
#include "core/rendering/HitTestResult.h"
#include "core/rendering/RenderLayer.h"

namespace WebCore {

using namespace HTMLNames;

static inline bool isShadowInsertionPointFocusScopeOwner(Node& node)
{
    return isActiveShadowInsertionPoint(node) && toHTMLShadowElement(node).olderShadowRoot();
}

// FIXME: Some of Node* return values and Node* arguments should be Element*.

FocusNavigationScope::FocusNavigationScope(TreeScope* treeScope)
    : m_rootTreeScope(treeScope)
{
    ASSERT(treeScope);
}

Node* FocusNavigationScope::rootNode() const
{
    return &m_rootTreeScope->rootNode();
}

Element* FocusNavigationScope::owner() const
{
    Node* root = rootNode();
    if (root->isShadowRoot()) {
        ShadowRoot* shadowRoot = toShadowRoot(root);
        return shadowRoot->isYoungest() ? shadowRoot->host() : shadowRoot->shadowInsertionPointOfYoungerShadowRoot();
    }
    if (Frame* frame = root->document().frame())
        return frame->ownerElement();
    return 0;
}

FocusNavigationScope FocusNavigationScope::focusNavigationScopeOf(Node* node)
{
    ASSERT(node);
    Node* root = node;
    for (Node* n = node; n; n = n->parentNode())
        root = n;
    // The result is not always a ShadowRoot nor a DocumentNode since
    // a starting node is in an orphaned tree in composed shadow tree.
    return FocusNavigationScope(&root->treeScope());
}

FocusNavigationScope FocusNavigationScope::ownedByNonFocusableFocusScopeOwner(Node* node)
{
    ASSERT(node);
    if (isShadowHost(node))
        return FocusNavigationScope::ownedByShadowHost(node);
    ASSERT(isShadowInsertionPointFocusScopeOwner(*node));
    return FocusNavigationScope::ownedByShadowInsertionPoint(toHTMLShadowElement(node));
}

FocusNavigationScope FocusNavigationScope::ownedByShadowHost(Node* node)
{
    ASSERT(isShadowHost(node));
    return FocusNavigationScope(toElement(node)->shadow()->youngestShadowRoot());
}

FocusNavigationScope FocusNavigationScope::ownedByIFrame(HTMLFrameOwnerElement* frame)
{
    ASSERT(frame && frame->contentFrame());
    return FocusNavigationScope(frame->contentFrame()->document());
}

FocusNavigationScope FocusNavigationScope::ownedByShadowInsertionPoint(HTMLShadowElement* shadowInsertionPoint)
{
    ASSERT(isShadowInsertionPointFocusScopeOwner(*shadowInsertionPoint));
    return FocusNavigationScope(shadowInsertionPoint->olderShadowRoot());
}

static inline void dispatchEventsOnWindowAndFocusedNode(Document* document, bool focused)
{
    // If we have a focused node we should dispatch blur on it before we blur the window.
    // If we have a focused node we should dispatch focus on it after we focus the window.
    // https://bugs.webkit.org/show_bug.cgi?id=27105

    // Do not fire events while modal dialogs are up.  See https://bugs.webkit.org/show_bug.cgi?id=33962
    if (Page* page = document->page()) {
        if (page->defersLoading())
            return;
    }

    if (!focused && document->focusedElement()) {
        RefPtr<Element> focusedElement(document->focusedElement());
        focusedElement->setFocus(false);
        focusedElement->dispatchBlurEvent(0);
        if (focusedElement == document->focusedElement()) {
            focusedElement->dispatchFocusOutEvent(EventTypeNames::focusout, 0);
            if (focusedElement == document->focusedElement())
                focusedElement->dispatchFocusOutEvent(EventTypeNames::DOMFocusOut, 0);
        }
    }

    if (DOMWindow* window = document->domWindow())
        window->dispatchEvent(Event::create(focused ? EventTypeNames::focus : EventTypeNames::blur));
    if (focused && document->focusedElement()) {
        RefPtr<Element> focusedElement(document->focusedElement());
        focusedElement->setFocus(true);
        focusedElement->dispatchFocusEvent(0, FocusTypePage);
        if (focusedElement == document->focusedElement()) {
            document->focusedElement()->dispatchFocusInEvent(EventTypeNames::focusin, 0);
            if (focusedElement == document->focusedElement())
                document->focusedElement()->dispatchFocusInEvent(EventTypeNames::DOMFocusIn, 0);
        }
    }
}

static inline bool hasCustomFocusLogic(Element* element)
{
    return element->isHTMLElement() && toHTMLElement(element)->hasCustomFocusLogic();
}

#if !ASSERT_DISABLED
static inline bool isNonFocusableShadowHost(Node* node)
{
    ASSERT(node);
    if (!node->isElementNode())
        return false;
    Element* element = toElement(node);
    return !element->isFocusable() && isShadowHost(element) && !hasCustomFocusLogic(element);
}
#endif

static inline bool isNonKeyboardFocusableShadowHost(Node* node)
{
    ASSERT(node);
    if (!node->isElementNode())
        return false;
    Element* element = toElement(node);
    return !element->isKeyboardFocusable() && isShadowHost(element) && !hasCustomFocusLogic(element);
}

static inline bool isKeyboardFocusableShadowHost(Node* node)
{
    ASSERT(node);
    if (!node->isElementNode())
        return false;
    Element* element = toElement(node);
    return element->isKeyboardFocusable() && isShadowHost(element) && !hasCustomFocusLogic(element);
}

static inline bool isNonFocusableFocusScopeOwner(Node* node)
{
    ASSERT(node);
    return isNonKeyboardFocusableShadowHost(node) || isShadowInsertionPointFocusScopeOwner(*node);
}

static inline int adjustedTabIndex(Node* node)
{
    ASSERT(node);
    return isNonFocusableFocusScopeOwner(node) ? 0 : node->tabIndex();
}

static inline bool shouldVisit(Node* node)
{
    ASSERT(node);
    return (node->isElementNode() && toElement(node)->isKeyboardFocusable()) || isNonFocusableFocusScopeOwner(node);
}

FocusController::FocusController(Page* page)
    : m_page(page)
    , m_isActive(false)
    , m_isFocused(false)
    , m_isChangingFocusedFrame(false)
    , m_containingWindowIsVisible(false)
{
}

PassOwnPtr<FocusController> FocusController::create(Page* page)
{
    return adoptPtr(new FocusController(page));
}

void FocusController::setFocusedFrame(PassRefPtr<Frame> frame)
{
    ASSERT(!frame || frame->page() == m_page);
    if (m_focusedFrame == frame || m_isChangingFocusedFrame)
        return;

    m_isChangingFocusedFrame = true;

    RefPtr<LocalFrame> oldFrame = (m_focusedFrame && m_focusedFrame->isLocalFrame()) ? toLocalFrame(m_focusedFrame.get()) : 0;
    RefPtr<LocalFrame> newFrame = (frame && frame->isLocalFrame()) ? toLocalFrame(frame.get()) : 0;

    m_focusedFrame = frame.get();

    // Now that the frame is updated, fire events and update the selection focused states of both frames.
    if (oldFrame && oldFrame->view()) {
        oldFrame->selection().setFocused(false);
        oldFrame->domWindow()->dispatchEvent(Event::create(EventTypeNames::blur));
    }

    if (newFrame && newFrame->view() && isFocused()) {
        newFrame->selection().setFocused(true);
        newFrame->domWindow()->dispatchEvent(Event::create(EventTypeNames::focus));
    }

    m_isChangingFocusedFrame = false;

    m_page->chrome().client().focusedFrameChanged(newFrame.get());
}

Frame* FocusController::focusedOrMainFrame() const
{
    if (Frame* frame = focusedFrame())
        return frame;
    return m_page->mainFrame();
}

void FocusController::setFocused(bool focused)
{
    if (isFocused() == focused)
        return;

    m_isFocused = focused;

    if (!m_isFocused && focusedOrMainFrame()->isLocalFrame())
        toLocalFrame(focusedOrMainFrame())->eventHandler().stopAutoscroll();

    if (!m_focusedFrame)
        setFocusedFrame(m_page->mainFrame());

    // setFocusedFrame above might reject to update m_focusedFrame, or
    // m_focusedFrame might be changed by blur/focus event handlers.
    if (m_focusedFrame && m_focusedFrame->isLocalFrame() && toLocalFrame(m_focusedFrame.get())->view()) {
        toLocalFrame(m_focusedFrame.get())->selection().setFocused(focused);
        dispatchEventsOnWindowAndFocusedNode(toLocalFrame(m_focusedFrame.get())->document(), focused);
    }
}

Node* FocusController::findFocusableNodeDecendingDownIntoFrameDocument(FocusType type, Node* node)
{
    // The node we found might be a HTMLFrameOwnerElement, so descend down the tree until we find either:
    // 1) a focusable node, or
    // 2) the deepest-nested HTMLFrameOwnerElement.
    while (node && node->isFrameOwnerElement()) {
        HTMLFrameOwnerElement* owner = toHTMLFrameOwnerElement(node);
        if (!owner->contentFrame())
            break;
        Node* foundNode = findFocusableNode(type, FocusNavigationScope::ownedByIFrame(owner), 0);
        if (!foundNode)
            break;
        ASSERT(node != foundNode);
        node = foundNode;
    }
    return node;
}

bool FocusController::setInitialFocus(FocusType type)
{
    bool didAdvanceFocus = advanceFocus(type, true);

    // If focus is being set initially, accessibility needs to be informed that system focus has moved
    // into the web area again, even if focus did not change within WebCore. PostNotification is called instead
    // of handleFocusedUIElementChanged, because this will send the notification even if the element is the same.
    if (AXObjectCache* cache = focusedOrMainFrame()->document()->existingAXObjectCache())
        cache->postNotification(focusedOrMainFrame()->document(), AXObjectCache::AXFocusedUIElementChanged, true);

    return didAdvanceFocus;
}

bool FocusController::advanceFocus(FocusType type, bool initialFocus)
{
    switch (type) {
    case FocusTypeForward:
    case FocusTypeBackward:
        return advanceFocusInDocumentOrder(type, initialFocus);
    case FocusTypeLeft:
    case FocusTypeRight:
    case FocusTypeUp:
    case FocusTypeDown:
        return advanceFocusDirectionally(type);
    default:
        ASSERT_NOT_REACHED();
    }

    return false;
}

bool FocusController::advanceFocusInDocumentOrder(FocusType type, bool initialFocus)
{
    // FIXME: Focus advancement won't work with externally rendered frames until after
    // inter-frame focus control is moved out of Blink.
    if (!focusedOrMainFrame()->isLocalFrame())
        return false;
    LocalFrame* frame = toLocalFrame(focusedOrMainFrame());
    ASSERT(frame);
    Document* document = frame->document();

    Node* currentNode = document->focusedElement();
    // FIXME: Not quite correct when it comes to focus transitions leaving/entering the WebView itself
    bool caretBrowsing = frame->settings() && frame->settings()->caretBrowsingEnabled();

    if (caretBrowsing && !currentNode)
        currentNode = frame->selection().start().deprecatedNode();

    document->updateLayoutIgnorePendingStylesheets();

    RefPtr<Node> node = findFocusableNodeAcrossFocusScope(type, FocusNavigationScope::focusNavigationScopeOf(currentNode ? currentNode : document), currentNode);

    if (!node) {
        // We didn't find a node to focus, so we should try to pass focus to Chrome.
        if (!initialFocus && m_page->chrome().canTakeFocus(type)) {
            document->setFocusedElement(nullptr);
            setFocusedFrame(nullptr);
            m_page->chrome().takeFocus(type);
            return true;
        }

        // Chrome doesn't want focus, so we should wrap focus.
        node = findFocusableNodeRecursively(type, FocusNavigationScope::focusNavigationScopeOf(m_page->mainFrame()->document()), 0);
        node = findFocusableNodeDecendingDownIntoFrameDocument(type, node.get());

        if (!node)
            return false;
    }

    ASSERT(node);

    if (node == document->focusedElement())
        // Focus wrapped around to the same node.
        return true;

    if (!node->isElementNode())
        // FIXME: May need a way to focus a document here.
        return false;

    Element* element = toElement(node);
    if (element->isFrameOwnerElement() && (!isHTMLPlugInElement(*element) || !element->isKeyboardFocusable())) {
        // We focus frames rather than frame owners.
        // FIXME: We should not focus frames that have no scrollbars, as focusing them isn't useful to the user.
        HTMLFrameOwnerElement* owner = toHTMLFrameOwnerElement(element);
        if (!owner->contentFrame())
            return false;

        document->setFocusedElement(nullptr);
        setFocusedFrame(owner->contentFrame());
        return true;
    }

    // FIXME: It would be nice to just be able to call setFocusedElement(node)
    // here, but we can't do that because some elements (e.g. HTMLInputElement
    // and HTMLTextAreaElement) do extra work in their focus() methods.
    Document& newDocument = element->document();

    if (&newDocument != document) {
        // Focus is going away from this document, so clear the focused node.
        document->setFocusedElement(nullptr);
    }

    setFocusedFrame(newDocument.frame());

    if (caretBrowsing) {
        Position position = firstPositionInOrBeforeNode(element);
        VisibleSelection newSelection(position, position, DOWNSTREAM);
        frame->selection().setSelection(newSelection);
    }

    element->focus(false, type);
    return true;
}

Node* FocusController::findFocusableNodeAcrossFocusScope(FocusType type, FocusNavigationScope scope, Node* currentNode)
{
    ASSERT(!currentNode || !isNonFocusableShadowHost(currentNode));
    Node* found;
    if (currentNode && type == FocusTypeForward && isKeyboardFocusableShadowHost(currentNode)) {
        Node* foundInInnerFocusScope = findFocusableNodeRecursively(type, FocusNavigationScope::ownedByShadowHost(currentNode), 0);
        found = foundInInnerFocusScope ? foundInInnerFocusScope : findFocusableNodeRecursively(type, scope, currentNode);
    } else {
        found = findFocusableNodeRecursively(type, scope, currentNode);
    }

    // If there's no focusable node to advance to, move up the focus scopes until we find one.
    while (!found) {
        Node* owner = scope.owner();
        if (!owner)
            break;
        scope = FocusNavigationScope::focusNavigationScopeOf(owner);
        if (type == FocusTypeBackward && isKeyboardFocusableShadowHost(owner)) {
            found = owner;
            break;
        }
        found = findFocusableNodeRecursively(type, scope, owner);
    }
    found = findFocusableNodeDecendingDownIntoFrameDocument(type, found);
    return found;
}

Node* FocusController::findFocusableNodeRecursively(FocusType type, FocusNavigationScope scope, Node* start)
{
    // Starting node is exclusive.
    Node* found = findFocusableNode(type, scope, start);
    if (!found)
        return 0;
    if (type == FocusTypeForward) {
        if (!isNonFocusableFocusScopeOwner(found))
            return found;
        Node* foundInInnerFocusScope = findFocusableNodeRecursively(type, FocusNavigationScope::ownedByNonFocusableFocusScopeOwner(found), 0);
        return foundInInnerFocusScope ? foundInInnerFocusScope : findFocusableNodeRecursively(type, scope, found);
    }
    ASSERT(type == FocusTypeBackward);
    if (isKeyboardFocusableShadowHost(found)) {
        Node* foundInInnerFocusScope = findFocusableNodeRecursively(type, FocusNavigationScope::ownedByShadowHost(found), 0);
        return foundInInnerFocusScope ? foundInInnerFocusScope : found;
    }
    if (isNonFocusableFocusScopeOwner(found)) {
        Node* foundInInnerFocusScope = findFocusableNodeRecursively(type, FocusNavigationScope::ownedByNonFocusableFocusScopeOwner(found), 0);
        return foundInInnerFocusScope ? foundInInnerFocusScope :findFocusableNodeRecursively(type, scope, found);
    }
    return found;
}

Node* FocusController::findFocusableNode(FocusType type, FocusNavigationScope scope, Node* node)
{
    return type == FocusTypeForward ? nextFocusableNode(scope, node) : previousFocusableNode(scope, node);
}

Node* FocusController::findNodeWithExactTabIndex(Node* start, int tabIndex, FocusType type)
{
    // Search is inclusive of start
    for (Node* node = start; node; node = type == FocusTypeForward ? NodeTraversal::next(*node) : NodeTraversal::previous(*node)) {
        if (shouldVisit(node) && adjustedTabIndex(node) == tabIndex)
            return node;
    }
    return 0;
}

static Node* nextNodeWithGreaterTabIndex(Node* start, int tabIndex)
{
    // Search is inclusive of start
    int winningTabIndex = std::numeric_limits<short>::max() + 1;
    Node* winner = 0;
    for (Node* node = start; node; node = NodeTraversal::next(*node)) {
        if (shouldVisit(node) && node->tabIndex() > tabIndex && node->tabIndex() < winningTabIndex) {
            winner = node;
            winningTabIndex = node->tabIndex();
        }
    }

    return winner;
}

static Node* previousNodeWithLowerTabIndex(Node* start, int tabIndex)
{
    // Search is inclusive of start
    int winningTabIndex = 0;
    Node* winner = 0;
    for (Node* node = start; node; node = NodeTraversal::previous(*node)) {
        int currentTabIndex = adjustedTabIndex(node);
        if ((shouldVisit(node) || isNonKeyboardFocusableShadowHost(node)) && currentTabIndex < tabIndex && currentTabIndex > winningTabIndex) {
            winner = node;
            winningTabIndex = currentTabIndex;
        }
    }
    return winner;
}

Node* FocusController::nextFocusableNode(FocusNavigationScope scope, Node* start)
{
    if (start) {
        int tabIndex = adjustedTabIndex(start);
        // If a node is excluded from the normal tabbing cycle, the next focusable node is determined by tree order
        if (tabIndex < 0) {
            for (Node* node = NodeTraversal::next(*start); node; node = NodeTraversal::next(*node)) {
                if (shouldVisit(node) && adjustedTabIndex(node) >= 0)
                    return node;
            }
        }

        // First try to find a node with the same tabindex as start that comes after start in the scope.
        if (Node* winner = findNodeWithExactTabIndex(NodeTraversal::next(*start), tabIndex, FocusTypeForward))
            return winner;

        if (!tabIndex)
            // We've reached the last node in the document with a tabindex of 0. This is the end of the tabbing order.
            return 0;
    }

    // Look for the first node in the scope that:
    // 1) has the lowest tabindex that is higher than start's tabindex (or 0, if start is null), and
    // 2) comes first in the scope, if there's a tie.
    if (Node* winner = nextNodeWithGreaterTabIndex(scope.rootNode(), start ? adjustedTabIndex(start) : 0))
        return winner;

    // There are no nodes with a tabindex greater than start's tabindex,
    // so find the first node with a tabindex of 0.
    return findNodeWithExactTabIndex(scope.rootNode(), 0, FocusTypeForward);
}

Node* FocusController::previousFocusableNode(FocusNavigationScope scope, Node* start)
{
    Node* last = 0;
    for (Node* node = scope.rootNode(); node; node = node->lastChild())
        last = node;
    ASSERT(last);

    // First try to find the last node in the scope that comes before start and has the same tabindex as start.
    // If start is null, find the last node in the scope with a tabindex of 0.
    Node* startingNode;
    int startingTabIndex;
    if (start) {
        startingNode = NodeTraversal::previous(*start);
        startingTabIndex = adjustedTabIndex(start);
    } else {
        startingNode = last;
        startingTabIndex = 0;
    }

    // However, if a node is excluded from the normal tabbing cycle, the previous focusable node is determined by tree order
    if (startingTabIndex < 0) {
        for (Node* node = startingNode; node; node = NodeTraversal::previous(*node)) {
            if (shouldVisit(node) && adjustedTabIndex(node) >= 0)
                return node;
        }
    }

    if (Node* winner = findNodeWithExactTabIndex(startingNode, startingTabIndex, FocusTypeBackward))
        return winner;

    // There are no nodes before start with the same tabindex as start, so look for a node that:
    // 1) has the highest non-zero tabindex (that is less than start's tabindex), and
    // 2) comes last in the scope, if there's a tie.
    startingTabIndex = (start && startingTabIndex) ? startingTabIndex : std::numeric_limits<short>::max();
    return previousNodeWithLowerTabIndex(last, startingTabIndex);
}

static bool relinquishesEditingFocus(Node *node)
{
    ASSERT(node);
    ASSERT(node->rendererIsEditable());
    return node->document().frame() && node->rootEditableElement();
}

static void clearSelectionIfNeeded(LocalFrame* oldFocusedFrame, LocalFrame* newFocusedFrame, Node* newFocusedNode)
{
    if (!oldFocusedFrame || !newFocusedFrame)
        return;

    if (oldFocusedFrame->document() != newFocusedFrame->document())
        return;

    FrameSelection& selection = oldFocusedFrame->selection();
    if (selection.isNone())
        return;

    bool caretBrowsing = oldFocusedFrame->settings()->caretBrowsingEnabled();
    if (caretBrowsing)
        return;

    Node* selectionStartNode = selection.selection().start().deprecatedNode();
    if (selectionStartNode == newFocusedNode || selectionStartNode->isDescendantOf(newFocusedNode) || selectionStartNode->deprecatedShadowAncestorNode() == newFocusedNode)
        return;

    if (Node* mousePressNode = newFocusedFrame->eventHandler().mousePressNode()) {
        if (mousePressNode->renderer() && !mousePressNode->canStartSelection()) {
            // Don't clear the selection for contentEditable elements, but do clear it for input and textarea. See bug 38696.
            Node* root = selection.rootEditableElement();
            if (!root)
                return;

            if (Node* shadowAncestorNode = root->deprecatedShadowAncestorNode()) {
                if (!isHTMLInputElement(*shadowAncestorNode) && !isHTMLTextAreaElement(*shadowAncestorNode))
                    return;
            }
        }
    }

    selection.clear();
}

bool FocusController::setFocusedElement(Element* element, PassRefPtr<Frame> newFocusedFrame, FocusType type)
{
    RefPtr<LocalFrame> oldFocusedFrame = toLocalFrame(focusedFrame());
    RefPtr<Document> oldDocument = oldFocusedFrame ? oldFocusedFrame->document() : 0;

    Element* oldFocusedElement = oldDocument ? oldDocument->focusedElement() : 0;
    if (element && oldFocusedElement == element)
        return true;

    // FIXME: Might want to disable this check for caretBrowsing
    if (oldFocusedElement && oldFocusedElement->isRootEditableElement() && !relinquishesEditingFocus(oldFocusedElement))
        return false;

    m_page->chrome().client().willSetInputMethodState();

    RefPtr<Document> newDocument;
    if (element)
        newDocument = &element->document();
    else if (newFocusedFrame)
        newDocument = newFocusedFrame->document();

    if (newDocument && oldDocument == newDocument && newDocument->focusedElement() == element)
        return true;

    clearSelectionIfNeeded(oldFocusedFrame.get(), toLocalFrame(newFocusedFrame.get()), element);

    if (oldDocument && oldDocument != newDocument)
        oldDocument->setFocusedElement(nullptr);

    if (newFocusedFrame && !newFocusedFrame->page()) {
        setFocusedFrame(nullptr);
        return false;
    }
    setFocusedFrame(newFocusedFrame);

    // Setting the focused node can result in losing our last reft to node when JS event handlers fire.
    RefPtr<Element> protect = element;
    if (newDocument) {
        bool successfullyFocused = newDocument->setFocusedElement(element, type);
        if (!successfullyFocused)
            return false;
    }

    return true;
}

void FocusController::setActive(bool active)
{
    if (m_isActive == active)
        return;

    m_isActive = active;

    if (FrameView* view = m_page->mainFrame()->view())
        view->updateControlTints();

    toLocalFrame(focusedOrMainFrame())->selection().pageActivationChanged();
}

static void contentAreaDidShowOrHide(ScrollableArea* scrollableArea, bool didShow)
{
    if (didShow)
        scrollableArea->contentAreaDidShow();
    else
        scrollableArea->contentAreaDidHide();
}

void FocusController::setContainingWindowIsVisible(bool containingWindowIsVisible)
{
    if (m_containingWindowIsVisible == containingWindowIsVisible)
        return;

    m_containingWindowIsVisible = containingWindowIsVisible;

    FrameView* view = m_page->mainFrame()->view();
    if (!view)
        return;

    contentAreaDidShowOrHide(view, containingWindowIsVisible);

    for (LocalFrame* frame = m_page->mainFrame(); frame; frame = frame->tree().traverseNext()) {
        FrameView* frameView = frame->view();
        if (!frameView)
            continue;

        const HashSet<ScrollableArea*>* scrollableAreas = frameView->scrollableAreas();
        if (!scrollableAreas)
            continue;

        for (HashSet<ScrollableArea*>::const_iterator it = scrollableAreas->begin(), end = scrollableAreas->end(); it != end; ++it) {
            ScrollableArea* scrollableArea = *it;
            ASSERT(scrollableArea->scrollbarsCanBeActive());

            contentAreaDidShowOrHide(scrollableArea, containingWindowIsVisible);
        }
    }
}

static void updateFocusCandidateIfNeeded(FocusType type, const FocusCandidate& current, FocusCandidate& candidate, FocusCandidate& closest)
{
    ASSERT(candidate.visibleNode->isElementNode());
    ASSERT(candidate.visibleNode->renderer());

    // Ignore iframes that don't have a src attribute
    if (frameOwnerElement(candidate) && (!frameOwnerElement(candidate)->contentFrame() || candidate.rect.isEmpty()))
        return;

    // Ignore off screen child nodes of containers that do not scroll (overflow:hidden)
    if (candidate.isOffscreen && !canBeScrolledIntoView(type, candidate))
        return;

    distanceDataForNode(type, current, candidate);
    if (candidate.distance == maxDistance())
        return;

    if (candidate.isOffscreenAfterScrolling && candidate.alignment < Full)
        return;

    if (closest.isNull()) {
        closest = candidate;
        return;
    }

    LayoutRect intersectionRect = intersection(candidate.rect, closest.rect);
    if (!intersectionRect.isEmpty() && !areElementsOnSameLine(closest, candidate)) {
        // If 2 nodes are intersecting, do hit test to find which node in on top.
        LayoutUnit x = intersectionRect.x() + intersectionRect.width() / 2;
        LayoutUnit y = intersectionRect.y() + intersectionRect.height() / 2;
        HitTestResult result = candidate.visibleNode->document().page()->mainFrame()->eventHandler().hitTestResultAtPoint(IntPoint(x, y), HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::IgnoreClipping | HitTestRequest::ConfusingAndOftenMisusedDisallowShadowContent);
        if (candidate.visibleNode->contains(result.innerNode())) {
            closest = candidate;
            return;
        }
        if (closest.visibleNode->contains(result.innerNode()))
            return;
    }

    if (candidate.alignment == closest.alignment) {
        if (candidate.distance < closest.distance)
            closest = candidate;
        return;
    }

    if (candidate.alignment > closest.alignment)
        closest = candidate;
}

void FocusController::findFocusCandidateInContainer(Node& container, const LayoutRect& startingRect, FocusType type, FocusCandidate& closest)
{
    Element* focusedElement = (focusedFrame() && focusedFrame()->document()) ? focusedFrame()->document()->focusedElement() : 0;

    Element* element = ElementTraversal::firstWithin(container);
    FocusCandidate current;
    current.rect = startingRect;
    current.focusableNode = focusedElement;
    current.visibleNode = focusedElement;

    for (; element; element = (element->isFrameOwnerElement() || canScrollInDirection(element, type))
        ? ElementTraversal::nextSkippingChildren(*element, &container)
        : ElementTraversal::next(*element, &container)) {
        if (element == focusedElement)
            continue;

        if (!element->isKeyboardFocusable() && !element->isFrameOwnerElement() && !canScrollInDirection(element, type))
            continue;

        FocusCandidate candidate = FocusCandidate(element, type);
        if (candidate.isNull())
            continue;

        candidate.enclosingScrollableBox = &container;
        updateFocusCandidateIfNeeded(type, current, candidate, closest);
    }
}

bool FocusController::advanceFocusDirectionallyInContainer(Node* container, const LayoutRect& startingRect, FocusType type)
{
    if (!container)
        return false;

    LayoutRect newStartingRect = startingRect;

    if (startingRect.isEmpty())
        newStartingRect = virtualRectForDirection(type, nodeRectInAbsoluteCoordinates(container));

    // Find the closest node within current container in the direction of the navigation.
    FocusCandidate focusCandidate;
    findFocusCandidateInContainer(*container, newStartingRect, type, focusCandidate);

    if (focusCandidate.isNull()) {
        // Nothing to focus, scroll if possible.
        // NOTE: If no scrolling is performed (i.e. scrollInDirection returns false), the
        // spatial navigation algorithm will skip this container.
        return scrollInDirection(container, type);
    }

    if (HTMLFrameOwnerElement* frameElement = frameOwnerElement(focusCandidate)) {
        // If we have an iframe without the src attribute, it will not have a contentFrame().
        // We ASSERT here to make sure that
        // updateFocusCandidateIfNeeded() will never consider such an iframe as a candidate.
        ASSERT(frameElement->contentFrame());

        if (focusCandidate.isOffscreenAfterScrolling) {
            scrollInDirection(&focusCandidate.visibleNode->document(), type);
            return true;
        }
        // Navigate into a new frame.
        LayoutRect rect;
        Element* focusedElement = focusedOrMainFrame()->document()->focusedElement();
        if (focusedElement && !hasOffscreenRect(focusedElement))
            rect = nodeRectInAbsoluteCoordinates(focusedElement, true /* ignore border */);
        frameElement->contentFrame()->document()->updateLayoutIgnorePendingStylesheets();
        if (!advanceFocusDirectionallyInContainer(frameElement->contentFrame()->document(), rect, type)) {
            // The new frame had nothing interesting, need to find another candidate.
            return advanceFocusDirectionallyInContainer(container, nodeRectInAbsoluteCoordinates(focusCandidate.visibleNode, true), type);
        }
        return true;
    }

    if (canScrollInDirection(focusCandidate.visibleNode, type)) {
        if (focusCandidate.isOffscreenAfterScrolling) {
            scrollInDirection(focusCandidate.visibleNode, type);
            return true;
        }
        // Navigate into a new scrollable container.
        LayoutRect startingRect;
        Element* focusedElement = focusedOrMainFrame()->document()->focusedElement();
        if (focusedElement && !hasOffscreenRect(focusedElement))
            startingRect = nodeRectInAbsoluteCoordinates(focusedElement, true);
        return advanceFocusDirectionallyInContainer(focusCandidate.visibleNode, startingRect, type);
    }
    if (focusCandidate.isOffscreenAfterScrolling) {
        Node* container = focusCandidate.enclosingScrollableBox;
        scrollInDirection(container, type);
        return true;
    }

    // We found a new focus node, navigate to it.
    Element* element = toElement(focusCandidate.focusableNode);
    ASSERT(element);

    element->focus(false, type);
    return true;
}

bool FocusController::advanceFocusDirectionally(FocusType type)
{
    // FIXME: Directional focus changes don't yet work with RemoteFrames.
    if (!focusedOrMainFrame()->isLocalFrame())
        return false;
    LocalFrame* curFrame = toLocalFrame(focusedOrMainFrame());
    ASSERT(curFrame);

    Document* focusedDocument = curFrame->document();
    if (!focusedDocument)
        return false;

    Element* focusedElement = focusedDocument->focusedElement();
    Node* container = focusedDocument;

    if (container->isDocumentNode())
        toDocument(container)->updateLayoutIgnorePendingStylesheets();

    // Figure out the starting rect.
    LayoutRect startingRect;
    if (focusedElement) {
        if (!hasOffscreenRect(focusedElement)) {
            container = scrollableEnclosingBoxOrParentFrameForNodeInDirection(type, focusedElement);
            startingRect = nodeRectInAbsoluteCoordinates(focusedElement, true /* ignore border */);
        } else if (isHTMLAreaElement(*focusedElement)) {
            HTMLAreaElement& area = toHTMLAreaElement(*focusedElement);
            container = scrollableEnclosingBoxOrParentFrameForNodeInDirection(type, area.imageElement());
            startingRect = virtualRectForAreaElementAndDirection(area, type);
        }
    }

    bool consumed = false;
    do {
        consumed = advanceFocusDirectionallyInContainer(container, startingRect, type);
        startingRect = nodeRectInAbsoluteCoordinates(container, true /* ignore border */);
        container = scrollableEnclosingBoxOrParentFrameForNodeInDirection(type, container);
        if (container && container->isDocumentNode())
            toDocument(container)->updateLayoutIgnorePendingStylesheets();
    } while (!consumed && container);

    return consumed;
}

} // namespace WebCore