xref: /external/webkit/Source/WebCore/page/EventHandler.cpp

/*
 * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
 *
 * 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 "EventHandler.h"

#include "AXObjectCache.h"
#include "CachedImage.h"
#include "Chrome.h"
#include "ChromeClient.h"
#include "Cursor.h"
#include "CursorList.h"
#include "Document.h"
#include "DragController.h"
#include "Editor.h"
#include "EventNames.h"
#include "EventQueue.h"
#include "FloatPoint.h"
#include "FloatRect.h"
#include "FocusController.h"
#include "Frame.h"
#include "FrameLoader.h"
#include "FrameTree.h"
#include "FrameView.h"
#include "htmlediting.h"
#include "HTMLFrameElementBase.h"
#include "HTMLFrameSetElement.h"
#include "HTMLInputElement.h"
#include "HTMLNames.h"
#include "HitTestRequest.h"
#include "HitTestResult.h"
#include "Image.h"
#include "InspectorInstrumentation.h"
#include "KeyboardEvent.h"
#include "MouseEvent.h"
#include "MouseEventWithHitTestResults.h"
#include "Page.h"
#include "PlatformKeyboardEvent.h"
#include "PlatformWheelEvent.h"
#include "PluginDocument.h"
#if defined(ANDROID_PLUGINS)
#include "PluginView.h"
#endif
#include "RenderFrameSet.h"
#include "RenderLayer.h"
#include "RenderTextControlSingleLine.h"
#include "RenderView.h"
#include "RenderWidget.h"
#include "ScrollAnimator.h"
#include "Scrollbar.h"
#include "SelectionController.h"
#include "Settings.h"
#include "StyleCachedImage.h"
#include "TextEvent.h"
#include "TextIterator.h"
#include "UserGestureIndicator.h"
#include "UserTypingGestureIndicator.h"
#include "WheelEvent.h"
#include <wtf/CurrentTime.h>
#include <wtf/StdLibExtras.h>

#if ENABLE(GESTURE_EVENTS)
#include "PlatformGestureEvent.h"
#endif

#if ENABLE(SVG)
#include "SVGDocument.h"
#include "SVGElementInstance.h"
#include "SVGNames.h"
#include "SVGUseElement.h"
#endif

#if ENABLE(TOUCH_EVENTS)
#include "PlatformTouchEvent.h"
#include "TouchEvent.h"
#endif

<<<<<<< HEAD
#if defined(ANDROID_PLUGINS)
#include "WebViewCore.h"
=======
#if ENABLE(GESTURE_RECOGNIZER)
#include "PlatformGestureRecognizer.h"
>>>>>>> webkit.org at r82507
#endif

namespace WebCore {

using namespace HTMLNames;

#if ENABLE(DRAG_SUPPORT)
// The link drag hysteresis is much larger than the others because there
// needs to be enough space to cancel the link press without starting a link drag,
// and because dragging links is rare.
const int LinkDragHysteresis = 40;
const int ImageDragHysteresis = 5;
const int TextDragHysteresis = 3;
const int GeneralDragHysteresis = 3;
#endif // ENABLE(DRAG_SUPPORT)

// Match key code of composition keydown event on windows.
// IE sends VK_PROCESSKEY which has value 229;
const int CompositionEventKeyCode = 229;

#if ENABLE(SVG)
using namespace SVGNames;
#endif

// When the autoscroll or the panScroll is triggered when do the scroll every 0.05s to make it smooth
const double autoscrollInterval = 0.05;

const double fakeMouseMoveInterval = 0.1;

static Frame* subframeForHitTestResult(const MouseEventWithHitTestResults&);

static inline bool scrollNode(float delta, WheelEvent::Granularity granularity, ScrollDirection positiveDirection, ScrollDirection negativeDirection, Node* node, Node** stopNode)
{
    if (!delta)
        return false;

    if (!node->renderer())
        return false;

    // Find the nearest enclosing box.
    RenderBox* enclosingBox = node->renderer()->enclosingBox();

    float absDelta = delta > 0 ? delta : -delta;

    if (granularity == WheelEvent::Page)
        return enclosingBox->scroll(delta < 0 ? negativeDirection : positiveDirection, ScrollByPage, absDelta, stopNode);

    if (granularity == WheelEvent::Line)
        return enclosingBox->scroll(delta < 0 ? negativeDirection : positiveDirection, ScrollByLine, absDelta, stopNode);

    if (granularity == WheelEvent::Pixel)
        return enclosingBox->scroll(delta < 0 ? negativeDirection : positiveDirection, ScrollByPixel, absDelta, stopNode);

    return false;
}

#if !PLATFORM(MAC)

inline bool EventHandler::eventLoopHandleMouseUp(const MouseEventWithHitTestResults&)
{
    return false;
}

#if ENABLE(DRAG_SUPPORT)
inline bool EventHandler::eventLoopHandleMouseDragged(const MouseEventWithHitTestResults&)
{
    return false;
}
#endif

#endif

EventHandler::EventHandler(Frame* frame)
    : m_frame(frame)
    , m_mousePressed(false)
    , m_capturesDragging(false)
    , m_mouseDownMayStartSelect(false)
#if ENABLE(DRAG_SUPPORT)
    , m_mouseDownMayStartDrag(false)
#endif
    , m_mouseDownWasSingleClickInSelection(false)
    , m_beganSelectingText(false)
    , m_panScrollInProgress(false)
    , m_panScrollButtonPressed(false)
    , m_springLoadedPanScrollInProgress(false)
    , m_hoverTimer(this, &EventHandler::hoverTimerFired)
    , m_autoscrollTimer(this, &EventHandler::autoscrollTimerFired)
    , m_autoscrollRenderer(0)
    , m_autoscrollInProgress(false)
    , m_mouseDownMayStartAutoscroll(false)
    , m_mouseDownWasInSubframe(false)
    , m_fakeMouseMoveEventTimer(this, &EventHandler::fakeMouseMoveEventTimerFired)
#if ENABLE(SVG)
    , m_svgPan(false)
#endif
    , m_resizeLayer(0)
    , m_eventHandlerWillResetCapturingMouseEventsNode(0)
    , m_clickCount(0)
    , m_mouseDownTimestamp(0)
    , m_useLatchedWheelEventNode(false)
    , m_widgetIsLatched(false)
#if PLATFORM(MAC)
    , m_mouseDownView(nil)
    , m_sendingEventToSubview(false)
    , m_activationEventNumber(-1)
#endif
#if ENABLE(TOUCH_EVENTS)
    , m_touchPressed(false)
#endif
#if ENABLE(GESTURE_RECOGNIZER)
    , m_gestureRecognizer(PlatformGestureRecognizer::create())
#endif
{
}

EventHandler::~EventHandler()
{
    ASSERT(!m_fakeMouseMoveEventTimer.isActive());
}

#if ENABLE(DRAG_SUPPORT)
EventHandler::EventHandlerDragState& EventHandler::dragState()
{
    DEFINE_STATIC_LOCAL(EventHandlerDragState, state, ());
    return state;
}
#endif // ENABLE(DRAG_SUPPORT)

void EventHandler::clear()
{
    m_hoverTimer.stop();
    m_fakeMouseMoveEventTimer.stop();
    m_resizeLayer = 0;
    m_nodeUnderMouse = 0;
    m_lastNodeUnderMouse = 0;
#if ENABLE(SVG)
    m_instanceUnderMouse = 0;
    m_lastInstanceUnderMouse = 0;
#endif
    m_lastMouseMoveEventSubframe = 0;
    m_lastScrollbarUnderMouse = 0;
    m_clickCount = 0;
    m_clickNode = 0;
    m_frameSetBeingResized = 0;
#if ENABLE(DRAG_SUPPORT)
    m_dragTarget = 0;
    m_shouldOnlyFireDragOverEvent = false;
#endif
    m_currentMousePosition = IntPoint();
    m_mousePressNode = 0;
    m_mousePressed = false;
    m_capturesDragging = false;
    m_capturingMouseEventsNode = 0;
    m_latchedWheelEventNode = 0;
    m_previousWheelScrolledNode = 0;
#if ENABLE(TOUCH_EVENTS)
    m_originatingTouchPointTargets.clear();
#if PLATFORM(ANDROID)
    m_capturingTouchEventsNode = 0;
#endif
#endif
}

static void setSelectionIfNeeded(SelectionController* selection, const VisibleSelection& newSelection)
{
    ASSERT(selection);
    if (selection->selection() != newSelection && selection->shouldChangeSelection(newSelection))
        selection->setSelection(newSelection);
}

static void setNonDirectionalSelectionIfNeeded(SelectionController* selection, const VisibleSelection& newSelection, TextGranularity granularity)
{
    ASSERT(selection);
    if (selection->selection() != newSelection && selection->shouldChangeSelection(newSelection))
        selection->setSelection(newSelection, granularity, MakeNonDirectionalSelection);
}

void EventHandler::selectClosestWordFromMouseEvent(const MouseEventWithHitTestResults& result)
{
    Node* innerNode = result.targetNode();
    VisibleSelection newSelection;

    if (innerNode && innerNode->renderer() && m_mouseDownMayStartSelect) {
        VisiblePosition pos(innerNode->renderer()->positionForPoint(result.localPoint()));
        TextGranularity granularity = CharacterGranularity;
        if (pos.isNotNull()) {
            newSelection = VisibleSelection(pos);
            newSelection.expandUsingGranularity(WordGranularity);
        }

        if (newSelection.isRange()) {
            granularity = WordGranularity;
            m_beganSelectingText = true;
            if (result.event().clickCount() == 2 && m_frame->editor()->isSelectTrailingWhitespaceEnabled())
                newSelection.appendTrailingWhitespace();
        }

        setNonDirectionalSelectionIfNeeded(m_frame->selection(), newSelection, granularity);
    }
}

void EventHandler::selectClosestWordOrLinkFromMouseEvent(const MouseEventWithHitTestResults& result)
{
    if (!result.hitTestResult().isLiveLink())
        return selectClosestWordFromMouseEvent(result);

    Node* innerNode = result.targetNode();

    if (innerNode && innerNode->renderer() && m_mouseDownMayStartSelect) {
        VisibleSelection newSelection;
        Element* URLElement = result.hitTestResult().URLElement();
        VisiblePosition pos(innerNode->renderer()->positionForPoint(result.localPoint()));
        if (pos.isNotNull() && pos.deepEquivalent().deprecatedNode()->isDescendantOf(URLElement))
            newSelection = VisibleSelection::selectionFromContentsOfNode(URLElement);

        TextGranularity granularity = CharacterGranularity;
        if (newSelection.isRange()) {
            granularity = WordGranularity;
            m_beganSelectingText = true;
        }

        setNonDirectionalSelectionIfNeeded(m_frame->selection(), newSelection, granularity);
    }
}

bool EventHandler::handleMousePressEventDoubleClick(const MouseEventWithHitTestResults& event)
{
    if (event.event().button() != LeftButton)
        return false;

    if (m_frame->selection()->isRange())
        // A double-click when range is already selected
        // should not change the selection.  So, do not call
        // selectClosestWordFromMouseEvent, but do set
        // m_beganSelectingText to prevent handleMouseReleaseEvent
        // from setting caret selection.
        m_beganSelectingText = true;
    else
        selectClosestWordFromMouseEvent(event);

    return true;
}

bool EventHandler::handleMousePressEventTripleClick(const MouseEventWithHitTestResults& event)
{
    if (event.event().button() != LeftButton)
        return false;

    Node* innerNode = event.targetNode();
    if (!(innerNode && innerNode->renderer() && m_mouseDownMayStartSelect))
        return false;

    VisibleSelection newSelection;
    VisiblePosition pos(innerNode->renderer()->positionForPoint(event.localPoint()));
    if (pos.isNotNull()) {
        newSelection = VisibleSelection(pos);
        newSelection.expandUsingGranularity(ParagraphGranularity);
    }

    TextGranularity granularity = CharacterGranularity;
    if (newSelection.isRange()) {
        granularity = ParagraphGranularity;
        m_beganSelectingText = true;
    }

    setNonDirectionalSelectionIfNeeded(m_frame->selection(), newSelection, granularity);

    return true;
}

static int textDistance(const Position& start, const Position& end)
{
     RefPtr<Range> range = Range::create(start.anchorNode()->document(), start, end);
     return TextIterator::rangeLength(range.get(), true);
}

bool EventHandler::handleMousePressEventSingleClick(const MouseEventWithHitTestResults& event)
{
    Node* innerNode = event.targetNode();
    if (!(innerNode && innerNode->renderer() && m_mouseDownMayStartSelect))
        return false;

    // Extend the selection if the Shift key is down, unless the click is in a link.
    bool extendSelection = event.event().shiftKey() && !event.isOverLink();

    // Don't restart the selection when the mouse is pressed on an
    // existing selection so we can allow for text dragging.
    if (FrameView* view = m_frame->view()) {
        IntPoint vPoint = view->windowToContents(event.event().pos());
        if (!extendSelection && m_frame->selection()->contains(vPoint)) {
            m_mouseDownWasSingleClickInSelection = true;
            return false;
        }
    }

    VisiblePosition visiblePos(innerNode->renderer()->positionForPoint(event.localPoint()));
    if (visiblePos.isNull())
        visiblePos = VisiblePosition(firstPositionInOrBeforeNode(innerNode), DOWNSTREAM);
    Position pos = visiblePos.deepEquivalent();

    VisibleSelection newSelection = m_frame->selection()->selection();
    TextGranularity granularity = CharacterGranularity;

    if (extendSelection && newSelection.isCaretOrRange()) {
        m_frame->selection()->setIsDirectional(false);

        ASSERT(m_frame->settings());
        if (m_frame->settings()->editingBehaviorType() == EditingMacBehavior) {
            // See <rdar://problem/3668157> REGRESSION (Mail): shift-click deselects when selection
            // was created right-to-left
            Position start = newSelection.start();
            Position end = newSelection.end();
            int distanceToStart = textDistance(start, pos);
            int distanceToEnd = textDistance(pos, end);
            if (distanceToStart <= distanceToEnd)
                newSelection = VisibleSelection(end, pos);
            else
                newSelection = VisibleSelection(start, pos);
        } else {
            newSelection.setExtent(pos);
        }

        if (m_frame->selection()->granularity() != CharacterGranularity) {
            granularity = m_frame->selection()->granularity();
            newSelection.expandUsingGranularity(m_frame->selection()->granularity());
        }

        m_beganSelectingText = true;
    } else
        newSelection = VisibleSelection(visiblePos);

    setNonDirectionalSelectionIfNeeded(m_frame->selection(), newSelection, granularity);

    return true;
}

bool EventHandler::handleMousePressEvent(const MouseEventWithHitTestResults& event)
{
#if ENABLE(DRAG_SUPPORT)
    // Reset drag state.
    dragState().m_dragSrc = 0;
#endif

    cancelFakeMouseMoveEvent();

    if (ScrollView* scrollView = m_frame->view()) {
        if (scrollView->isPointInScrollbarCorner(event.event().pos()))
            return false;
    }

    bool singleClick = event.event().clickCount() <= 1;

    // If we got the event back, that must mean it wasn't prevented,
    // so it's allowed to start a drag or selection.
    m_mouseDownMayStartSelect = canMouseDownStartSelect(event.targetNode());

#if ENABLE(DRAG_SUPPORT)
    // Careful that the drag starting logic stays in sync with eventMayStartDrag()
    m_mouseDownMayStartDrag = singleClick;
#endif

    m_mouseDownWasSingleClickInSelection = false;

    m_mouseDown = event.event();

    if (event.isOverWidget() && passWidgetMouseDownEventToWidget(event))
        return true;

#if ENABLE(SVG)
    if (m_frame->document()->isSVGDocument()
        && static_cast<SVGDocument*>(m_frame->document())->zoomAndPanEnabled()) {
        if (event.event().shiftKey() && singleClick) {
            m_svgPan = true;
            static_cast<SVGDocument*>(m_frame->document())->startPan(event.event().pos());
            return true;
        }
    }
#endif

    // We don't do this at the start of mouse down handling,
    // because we don't want to do it until we know we didn't hit a widget.
    if (singleClick)
        focusDocumentView();

    Node* innerNode = event.targetNode();

    m_mousePressNode = innerNode;
#if ENABLE(DRAG_SUPPORT)
    m_dragStartPos = event.event().pos();
#endif

    bool swallowEvent = false;
    m_mousePressed = true;
    m_beganSelectingText = false;

    if (event.event().clickCount() == 2)
        swallowEvent = handleMousePressEventDoubleClick(event);
    else if (event.event().clickCount() >= 3)
        swallowEvent = handleMousePressEventTripleClick(event);
    else
        swallowEvent = handleMousePressEventSingleClick(event);

    m_mouseDownMayStartAutoscroll = m_mouseDownMayStartSelect
        || (m_mousePressNode && m_mousePressNode->renderBox() && m_mousePressNode->renderBox()->canBeProgramaticallyScrolled(true));

    return swallowEvent;
}

// There are two kinds of renderer that can autoscroll.
static bool canAutoscroll(RenderObject* renderer)
{
    if (!renderer->isBox())
        return false;

    // Check for a box that can be scrolled in its own right.
    if (toRenderBox(renderer)->canBeScrolledAndHasScrollableArea())
        return true;

    // Check for a box that represents the top level of a web page.
    // This can be scrolled by calling Chrome::scrollRectIntoView.
    // This only has an effect on the Mac platform in applications
    // that put web views into scrolling containers, such as Mac OS X Mail.
    // The code for this is in RenderLayer::scrollRectToVisible.
    if (renderer->node() != renderer->document())
        return false;
    Frame* frame = renderer->frame();
    if (!frame)
        return false;
    Page* page = frame->page();
    return page && page->mainFrame() == frame;
}

#if ENABLE(DRAG_SUPPORT)
bool EventHandler::handleMouseDraggedEvent(const MouseEventWithHitTestResults& event)
{
    if (handleDrag(event))
        return true;

    if (!m_mousePressed)
        return false;

    Node* targetNode = event.targetNode();
    if (event.event().button() != LeftButton || !targetNode || !targetNode->renderer())
        return false;

#if PLATFORM(MAC) // FIXME: Why does this assertion fire on other platforms?
    ASSERT(m_mouseDownMayStartSelect || m_mouseDownMayStartAutoscroll);
#endif

    m_mouseDownMayStartDrag = false;

    if (m_mouseDownMayStartAutoscroll && !m_panScrollInProgress) {
        // Find a renderer that can autoscroll.
        RenderObject* renderer = targetNode->renderer();
        while (renderer && !canAutoscroll(renderer)) {
            if (!renderer->parent() && renderer->node() == renderer->document() && renderer->document()->ownerElement())
                renderer = renderer->document()->ownerElement()->renderer();
            else
                renderer = renderer->parent();
        }

        if (renderer) {
            m_autoscrollInProgress = true;
            handleAutoscroll(renderer);
        }

        m_mouseDownMayStartAutoscroll = false;
    }

    if (!m_beganSelectingText) {
        HitTestRequest request(HitTestRequest::ReadOnly | HitTestRequest::Active);
        HitTestResult result(m_mouseDownPos);
        m_frame->document()->renderView()->layer()->hitTest(request, result);
        updateSelectionForMouseDrag(result.innerNode(), result.localPoint());
    }
    updateSelectionForMouseDrag(targetNode, event.localPoint());
    return true;
}

bool EventHandler::eventMayStartDrag(const PlatformMouseEvent& event) const
{
    // This is a pre-flight check of whether the event might lead to a drag being started.  Be careful
    // that its logic needs to stay in sync with handleMouseMoveEvent() and the way we setMouseDownMayStartDrag
    // in handleMousePressEvent

    if (!m_frame->contentRenderer() || !m_frame->contentRenderer()->hasLayer())
        return false;

    if (event.button() != LeftButton || event.clickCount() != 1)
        return false;

    bool DHTMLFlag;
    bool UAFlag;
    allowDHTMLDrag(DHTMLFlag, UAFlag);
    if (!DHTMLFlag && !UAFlag)
        return false;

    FrameView* view = m_frame->view();
    if (!view)
        return false;

    HitTestRequest request(HitTestRequest::ReadOnly);
    HitTestResult result(view->windowToContents(event.pos()));
    m_frame->contentRenderer()->layer()->hitTest(request, result);
    bool srcIsDHTML;
    return result.innerNode() && result.innerNode()->renderer()->draggableNode(DHTMLFlag, UAFlag, result.point().x(), result.point().y(), srcIsDHTML);
}

void EventHandler::updateSelectionForMouseDrag()
{
    FrameView* view = m_frame->view();
    if (!view)
        return;
    RenderView* renderer = m_frame->contentRenderer();
    if (!renderer)
        return;
    RenderLayer* layer = renderer->layer();
    if (!layer)
        return;

    HitTestRequest request(HitTestRequest::ReadOnly |
                           HitTestRequest::Active |
                           HitTestRequest::MouseMove);
    HitTestResult result(view->windowToContents(m_currentMousePosition));
    layer->hitTest(request, result);
    updateSelectionForMouseDrag(result.innerNode(), result.localPoint());
}

void EventHandler::updateSelectionForMouseDrag(Node* targetNode, const IntPoint& localPoint)
{
    if (!m_mouseDownMayStartSelect)
        return;

    if (!targetNode)
        return;

    if (!canMouseDragExtendSelect(targetNode))
        return;

    RenderObject* targetRenderer = targetNode->renderer();
    if (!targetRenderer)
        return;

    VisiblePosition targetPosition(targetRenderer->positionForPoint(localPoint));

    // Don't modify the selection if we're not on a node.
    if (targetPosition.isNull())
        return;

    // Restart the selection if this is the first mouse move. This work is usually
    // done in handleMousePressEvent, but not if the mouse press was on an existing selection.
    VisibleSelection newSelection = m_frame->selection()->selection();

#if ENABLE(SVG)
    // Special case to limit selection to the containing block for SVG text.
    // FIXME: Isn't there a better non-SVG-specific way to do this?
    if (Node* selectionBaseNode = newSelection.base().deprecatedNode())
        if (RenderObject* selectionBaseRenderer = selectionBaseNode->renderer())
            if (selectionBaseRenderer->isSVGText())
                if (targetNode->renderer()->containingBlock() != selectionBaseRenderer->containingBlock())
                    return;
#endif

    if (!m_beganSelectingText) {
        m_beganSelectingText = true;
        newSelection = VisibleSelection(targetPosition);
    }

    newSelection.setExtent(targetPosition);
    if (m_frame->selection()->granularity() != CharacterGranularity)
        newSelection.expandUsingGranularity(m_frame->selection()->granularity());

    setNonDirectionalSelectionIfNeeded(m_frame->selection(), newSelection, m_frame->selection()->granularity());
}
#endif // ENABLE(DRAG_SUPPORT)

void EventHandler::lostMouseCapture()
{
    m_frame->selection()->setCaretBlinkingSuspended(false);
}

bool EventHandler::handleMouseUp(const MouseEventWithHitTestResults& event)
{
    if (eventLoopHandleMouseUp(event))
        return true;

    // If this was the first click in the window, we don't even want to clear the selection.
    // This case occurs when the user clicks on a draggable element, since we have to process
    // the mouse down and drag events to see if we might start a drag.  For other first clicks
    // in a window, we just don't acceptFirstMouse, and the whole down-drag-up sequence gets
    // ignored upstream of this layer.
    return eventActivatedView(event.event());
}

bool EventHandler::handleMouseReleaseEvent(const MouseEventWithHitTestResults& event)
{
    if (m_autoscrollInProgress)
        stopAutoscrollTimer();

    if (handleMouseUp(event))
        return true;

    // Used to prevent mouseMoveEvent from initiating a drag before
    // the mouse is pressed again.
    m_frame->selection()->setCaretBlinkingSuspended(false);
    m_mousePressed = false;
    m_capturesDragging = false;
#if ENABLE(DRAG_SUPPORT)
    m_mouseDownMayStartDrag = false;
#endif
    m_mouseDownMayStartSelect = false;
    m_mouseDownMayStartAutoscroll = false;
    m_mouseDownWasInSubframe = false;

    bool handled = false;

    // Clear the selection if the mouse didn't move after the last mouse
    // press and it's not a context menu click.  We do this so when clicking
    // on the selection, the selection goes away.  However, if we are
    // editing, place the caret.
    if (m_mouseDownWasSingleClickInSelection && !m_beganSelectingText
#if ENABLE(DRAG_SUPPORT)
            && m_dragStartPos == event.event().pos()
#endif
            && m_frame->selection()->isRange()
            && event.event().button() != RightButton) {
        VisibleSelection newSelection;
        Node* node = event.targetNode();
        bool caretBrowsing = m_frame->settings()->caretBrowsingEnabled();
        if (node && (caretBrowsing || node->rendererIsEditable()) && node->renderer()) {
            VisiblePosition pos = node->renderer()->positionForPoint(event.localPoint());
            newSelection = VisibleSelection(pos);
        }

        setSelectionIfNeeded(m_frame->selection(), newSelection);

        handled = true;
    }

    m_frame->selection()->notifyRendererOfSelectionChange(true);

    m_frame->selection()->selectFrameElementInParentIfFullySelected();

    return handled;
}

void EventHandler::handleAutoscroll(RenderObject* renderer)
{
    // We don't want to trigger the autoscroll or the panScroll if it's already active
    if (m_autoscrollTimer.isActive())
        return;

    setAutoscrollRenderer(renderer);

#if ENABLE(PAN_SCROLLING)
    if (m_panScrollInProgress) {
        m_panScrollStartPos = currentMousePosition();
        if (FrameView* view = m_frame->view())
            view->addPanScrollIcon(m_panScrollStartPos);
        // If we're not in the top frame we notify it that we doing a panScroll.
        if (Page* page = m_frame->page()) {
            Frame* mainFrame = page->mainFrame();
            if (m_frame != mainFrame)
                mainFrame->eventHandler()->setPanScrollInProgress(true);
        }
    }
#endif

    startAutoscrollTimer();
}

void EventHandler::autoscrollTimerFired(Timer<EventHandler>*)
{
    RenderObject* r = autoscrollRenderer();
    if (!r || !r->isBox()) {
        stopAutoscrollTimer();
        return;
    }

    if (m_autoscrollInProgress) {
        if (!m_mousePressed) {
            stopAutoscrollTimer();
            return;
        }
        toRenderBox(r)->autoscroll();
    } else {
        // we verify that the main frame hasn't received the order to stop the panScroll
        if (Page* page = m_frame->page()) {
            if (!page->mainFrame()->eventHandler()->panScrollInProgress()) {
                stopAutoscrollTimer();
                return;
            }
        }
#if ENABLE(PAN_SCROLLING)
        updatePanScrollState();
        toRenderBox(r)->panScroll(m_panScrollStartPos);
#endif
    }
}

#if ENABLE(PAN_SCROLLING)

void EventHandler::startPanScrolling(RenderObject* renderer)
{
    m_panScrollInProgress = true;
    m_panScrollButtonPressed = true;
    handleAutoscroll(renderer);
    invalidateClick();
}

void EventHandler::updatePanScrollState()
{
    FrameView* view = m_frame->view();
    if (!view)
        return;

    // At the original click location we draw a 4 arrowed icon. Over this icon there won't be any scroll
    // So we don't want to change the cursor over this area
    bool east = m_panScrollStartPos.x() < (m_currentMousePosition.x() - ScrollView::noPanScrollRadius);
    bool west = m_panScrollStartPos.x() > (m_currentMousePosition.x() + ScrollView::noPanScrollRadius);
    bool north = m_panScrollStartPos.y() > (m_currentMousePosition.y() + ScrollView::noPanScrollRadius);
    bool south = m_panScrollStartPos.y() < (m_currentMousePosition.y() - ScrollView::noPanScrollRadius);

    if ((east || west || north || south) && m_panScrollButtonPressed)
        m_springLoadedPanScrollInProgress = true;

    if (north) {
        if (east)
            view->setCursor(northEastPanningCursor());
        else if (west)
            view->setCursor(northWestPanningCursor());
        else
            view->setCursor(northPanningCursor());
    } else if (south) {
        if (east)
            view->setCursor(southEastPanningCursor());
        else if (west)
            view->setCursor(southWestPanningCursor());
        else
            view->setCursor(southPanningCursor());
    } else if (east)
        view->setCursor(eastPanningCursor());
    else if (west)
        view->setCursor(westPanningCursor());
    else
        view->setCursor(middlePanningCursor());
}

#endif // ENABLE(PAN_SCROLLING)

RenderObject* EventHandler::autoscrollRenderer() const
{
    return m_autoscrollRenderer;
}

void EventHandler::updateAutoscrollRenderer()
{
    if (!m_autoscrollRenderer)
        return;

    HitTestResult hitTest = hitTestResultAtPoint(m_panScrollStartPos, true);

    if (Node* nodeAtPoint = hitTest.innerNode())
        m_autoscrollRenderer = nodeAtPoint->renderer();

    while (m_autoscrollRenderer && !canAutoscroll(m_autoscrollRenderer))
        m_autoscrollRenderer = m_autoscrollRenderer->parent();
}

void EventHandler::setAutoscrollRenderer(RenderObject* renderer)
{
    m_autoscrollRenderer = renderer;
}

#if ENABLE(DRAG_SUPPORT)
void EventHandler::allowDHTMLDrag(bool& flagDHTML, bool& flagUA) const
{
    flagDHTML = false;
    flagUA = false;

    if (!m_frame)
        return;

    Page* page = m_frame->page();
    if (!page)
        return;

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

    unsigned mask = page->dragController()->delegateDragSourceAction(view->contentsToWindow(m_mouseDownPos));
    flagDHTML = (mask & DragSourceActionDHTML) != DragSourceActionNone;
    flagUA = ((mask & DragSourceActionImage) || (mask & DragSourceActionLink) || (mask & DragSourceActionSelection));
}
#endif // ENABLE(DRAG_SUPPORT)

HitTestResult EventHandler::hitTestResultAtPoint(const IntPoint& point, bool allowShadowContent, bool ignoreClipping, HitTestScrollbars testScrollbars, HitTestRequest::HitTestRequestType hitType, const IntSize& padding)
{
    HitTestResult result(point, padding.height(), padding.width(), padding.height(), padding.width());
    if (!m_frame->contentRenderer())
        return result;
    if (ignoreClipping)
        hitType |= HitTestRequest::IgnoreClipping;
    m_frame->contentRenderer()->layer()->hitTest(HitTestRequest(hitType), result);

    while (true) {
        Node* n = result.innerNode();
        if (!result.isOverWidget() || !n || !n->renderer() || !n->renderer()->isWidget())
            break;
        RenderWidget* renderWidget = toRenderWidget(n->renderer());
        Widget* widget = renderWidget->widget();
        if (!widget || !widget->isFrameView())
            break;
        Frame* frame = static_cast<HTMLFrameElementBase*>(n)->contentFrame();
        if (!frame || !frame->contentRenderer())
            break;
        FrameView* view = static_cast<FrameView*>(widget);
        IntPoint widgetPoint(result.localPoint().x() + view->scrollX() - renderWidget->borderLeft() - renderWidget->paddingLeft(),
            result.localPoint().y() + view->scrollY() - renderWidget->borderTop() - renderWidget->paddingTop());
        HitTestResult widgetHitTestResult(widgetPoint, padding.height(), padding.width(), padding.height(), padding.width());
        frame->contentRenderer()->layer()->hitTest(HitTestRequest(hitType), widgetHitTestResult);
        result = widgetHitTestResult;

        if (testScrollbars == ShouldHitTestScrollbars) {
            Scrollbar* eventScrollbar = view->scrollbarAtPoint(point);
            if (eventScrollbar)
                result.setScrollbar(eventScrollbar);
        }
    }

    // If our HitTestResult is not visible, then we started hit testing too far down the frame chain.
    // Another hit test at the main frame level should get us the correct visible result.
    Frame* resultFrame = result.innerNonSharedNode() ? result.innerNonSharedNode()->document()->frame() : 0;
    if (Page* page = m_frame->page()) {
        Frame* mainFrame = page->mainFrame();
        if (m_frame != mainFrame && resultFrame && resultFrame != mainFrame && !resultFrame->editor()->insideVisibleArea(result.point())) {
            FrameView* resultView = resultFrame->view();
            FrameView* mainView = mainFrame->view();
            if (resultView && mainView) {
                IntPoint windowPoint = resultView->contentsToWindow(result.point());
                IntPoint mainFramePoint = mainView->windowToContents(windowPoint);
                result = mainFrame->eventHandler()->hitTestResultAtPoint(mainFramePoint, allowShadowContent, ignoreClipping, testScrollbars, hitType, padding);
            }
        }
    }

    if (!allowShadowContent)
        result.setToNonShadowAncestor();

    return result;
}


void EventHandler::startAutoscrollTimer()
{
    m_autoscrollTimer.startRepeating(autoscrollInterval);
}

void EventHandler::stopAutoscrollTimer(bool rendererIsBeingDestroyed)
{
    if (m_autoscrollInProgress) {
        if (m_mouseDownWasInSubframe) {
            if (Frame* subframe = subframeForTargetNode(m_mousePressNode.get()))
                subframe->eventHandler()->stopAutoscrollTimer(rendererIsBeingDestroyed);
            return;
        }
    }

    if (autoscrollRenderer()) {
        if (!rendererIsBeingDestroyed && (m_autoscrollInProgress || m_panScrollInProgress))
            toRenderBox(autoscrollRenderer())->stopAutoscroll();
#if ENABLE(PAN_SCROLLING)
        if (m_panScrollInProgress) {
            if (FrameView* view = m_frame->view()) {
                view->removePanScrollIcon();
                view->setCursor(pointerCursor());
            }
        }
#endif

        setAutoscrollRenderer(0);
    }

    m_autoscrollTimer.stop();

    m_panScrollInProgress = false;
    m_springLoadedPanScrollInProgress = false;

    // If we're not in the top frame we notify it that we are not doing a panScroll any more.
    if (Page* page = m_frame->page()) {
        Frame* mainFrame = page->mainFrame();
        if (m_frame != mainFrame)
            mainFrame->eventHandler()->setPanScrollInProgress(false);
    }

    m_autoscrollInProgress = false;
}

Node* EventHandler::mousePressNode() const
{
    return m_mousePressNode.get();
}

void EventHandler::setMousePressNode(PassRefPtr<Node> node)
{
    m_mousePressNode = node;
}

bool EventHandler::scrollOverflow(ScrollDirection direction, ScrollGranularity granularity, Node* startingNode)
{
    Node* node = startingNode;

    if (!node)
        node = m_frame->document()->focusedNode();

    if (!node)
        node = m_mousePressNode.get();

    if (node) {
        RenderObject* r = node->renderer();
        if (r && !r->isListBox() && r->enclosingBox()->scroll(direction, granularity)) {
            setFrameWasScrolledByUser();
            return true;
        }
    }

    return false;
}

bool EventHandler::logicalScrollOverflow(ScrollLogicalDirection direction, ScrollGranularity granularity, Node* startingNode)
{
    Node* node = startingNode;

    if (!node)
        node = m_frame->document()->focusedNode();

    if (!node)
        node = m_mousePressNode.get();

    if (node) {
        RenderObject* r = node->renderer();
        if (r && !r->isListBox() && r->enclosingBox()->logicalScroll(direction, granularity)) {
            setFrameWasScrolledByUser();
            return true;
        }
    }

    return false;
}

bool EventHandler::scrollRecursively(ScrollDirection direction, ScrollGranularity granularity, Node* startingNode)
{
    // The layout needs to be up to date to determine if we can scroll. We may be
    // here because of an onLoad event, in which case the final layout hasn't been performed yet.
    m_frame->document()->updateLayoutIgnorePendingStylesheets();
    if (scrollOverflow(direction, granularity, startingNode))
        return true;
    Frame* frame = m_frame;
    FrameView* view = frame->view();
    if (view && view->scroll(direction, granularity))
        return true;
    frame = frame->tree()->parent();
    if (!frame)
        return false;
    return frame->eventHandler()->scrollRecursively(direction, granularity, m_frame->ownerElement());
}

bool EventHandler::logicalScrollRecursively(ScrollLogicalDirection direction, ScrollGranularity granularity, Node* startingNode)
{
    // The layout needs to be up to date to determine if we can scroll. We may be
    // here because of an onLoad event, in which case the final layout hasn't been performed yet.
    m_frame->document()->updateLayoutIgnorePendingStylesheets();
    if (logicalScrollOverflow(direction, granularity, startingNode))
        return true;
    Frame* frame = m_frame;
    FrameView* view = frame->view();

    bool scrolled = false;
#if PLATFORM(MAC)
    // Mac also resets the scroll position in the inline direction.
    if (granularity == ScrollByDocument && view && view->logicalScroll(ScrollInlineDirectionBackward, ScrollByDocument))
        scrolled = true;
#endif
    if (view && view->logicalScroll(direction, granularity))
        scrolled = true;

    if (scrolled)
        return true;

    frame = frame->tree()->parent();
    if (!frame)
        return false;

    return frame->eventHandler()->logicalScrollRecursively(direction, granularity, m_frame->ownerElement());
}

IntPoint EventHandler::currentMousePosition() const
{
    return m_currentMousePosition;
}

Frame* subframeForHitTestResult(const MouseEventWithHitTestResults& hitTestResult)
{
    if (!hitTestResult.isOverWidget())
        return 0;
    return EventHandler::subframeForTargetNode(hitTestResult.targetNode());
}

Frame* EventHandler::subframeForTargetNode(Node* node)
{
    if (!node)
        return 0;

    RenderObject* renderer = node->renderer();
    if (!renderer || !renderer->isWidget())
        return 0;

    Widget* widget = toRenderWidget(renderer)->widget();
    if (!widget || !widget->isFrameView())
        return 0;

    return static_cast<FrameView*>(widget)->frame();
}

static bool isSubmitImage(Node* node)
{
    return node && node->hasTagName(inputTag) && static_cast<HTMLInputElement*>(node)->isImageButton();
}

// Returns true if the node's editable block is not current focused for editing
static bool nodeIsNotBeingEdited(Node* node, Frame* frame)
{
    return frame->selection()->rootEditableElement() != node->rootEditableElement();
}

Cursor EventHandler::selectCursor(const MouseEventWithHitTestResults& event, Scrollbar* scrollbar)
{
    Node* node = event.targetNode();
    RenderObject* renderer = node ? node->renderer() : 0;
    RenderStyle* style = renderer ? renderer->style() : 0;

    bool horizontalText = !style || style->isHorizontalWritingMode();
    const Cursor& iBeam = horizontalText ? iBeamCursor() : verticalTextCursor();

    // During selection, use an I-beam no matter what we're over.
    // If you're capturing mouse events for a particular node, don't treat this as a selection.
    if (m_mousePressed && m_mouseDownMayStartSelect && m_frame->selection()->isCaretOrRange() && !m_capturingMouseEventsNode)
        return iBeam;

    if (renderer && renderer->isFrameSet()) {
        RenderFrameSet* frameSetRenderer = toRenderFrameSet(renderer);
        if (frameSetRenderer->canResizeRow(event.localPoint()))
            return rowResizeCursor();
        if (frameSetRenderer->canResizeColumn(event.localPoint()))
            return columnResizeCursor();
    }

    if (style && style->cursors()) {
        const CursorList* cursors = style->cursors();
        for (unsigned i = 0; i < cursors->size(); ++i) {
            const CachedImage* cimage = 0;
            StyleImage* image = (*cursors)[i].image();
            if (image && image->isCachedImage())
                cimage = static_cast<StyleCachedImage*>(image)->cachedImage();
            if (!cimage)
                continue;
            IntPoint hotSpot = (*cursors)[i].hotSpot();
            // Limit the size of cursors so that they cannot be used to cover UI elements in chrome.
            IntSize size = cimage->image()->size();
            if (size.width() > 128 || size.height() > 128)
                continue;
            if (cimage->image()->isNull())
                break;
            if (!cimage->errorOccurred())
                return Cursor(cimage->image(), hotSpot);
        }
    }

    switch (style ? style->cursor() : CURSOR_AUTO) {
    case CURSOR_AUTO: {
        bool editable = (node && node->rendererIsEditable());
        bool editableLinkEnabled = false;

        // If the link is editable, then we need to check the settings to see whether or not the link should be followed
        if (editable) {
            ASSERT(m_frame->settings());
            switch (m_frame->settings()->editableLinkBehavior()) {
            default:
            case EditableLinkDefaultBehavior:
            case EditableLinkAlwaysLive:
                editableLinkEnabled = true;
                break;

            case EditableLinkNeverLive:
                editableLinkEnabled = false;
                break;

            case EditableLinkLiveWhenNotFocused:
                editableLinkEnabled = nodeIsNotBeingEdited(node, m_frame) || event.event().shiftKey();
                break;

            case EditableLinkOnlyLiveWithShiftKey:
                editableLinkEnabled = event.event().shiftKey();
                break;
            }
        }

        if ((event.isOverLink() || isSubmitImage(node)) && (!editable || editableLinkEnabled))
            return handCursor();
        bool inResizer = false;
        if (renderer) {
            if (RenderLayer* layer = renderer->enclosingLayer()) {
                if (FrameView* view = m_frame->view())
                    inResizer = layer->isPointInResizeControl(view->windowToContents(event.event().pos()));
            }
        }
        if ((editable || (renderer && renderer->isText() && node->canStartSelection())) && !inResizer && !scrollbar)
            return iBeam;
        return pointerCursor();
    }
    case CURSOR_CROSS:
        return crossCursor();
    case CURSOR_POINTER:
        return handCursor();
    case CURSOR_MOVE:
        return moveCursor();
    case CURSOR_ALL_SCROLL:
        return moveCursor();
    case CURSOR_E_RESIZE:
        return eastResizeCursor();
    case CURSOR_W_RESIZE:
        return westResizeCursor();
    case CURSOR_N_RESIZE:
        return northResizeCursor();
    case CURSOR_S_RESIZE:
        return southResizeCursor();
    case CURSOR_NE_RESIZE:
        return northEastResizeCursor();
    case CURSOR_SW_RESIZE:
        return southWestResizeCursor();
    case CURSOR_NW_RESIZE:
        return northWestResizeCursor();
    case CURSOR_SE_RESIZE:
        return southEastResizeCursor();
    case CURSOR_NS_RESIZE:
        return northSouthResizeCursor();
    case CURSOR_EW_RESIZE:
        return eastWestResizeCursor();
    case CURSOR_NESW_RESIZE:
        return northEastSouthWestResizeCursor();
    case CURSOR_NWSE_RESIZE:
        return northWestSouthEastResizeCursor();
    case CURSOR_COL_RESIZE:
        return columnResizeCursor();
    case CURSOR_ROW_RESIZE:
        return rowResizeCursor();
    case CURSOR_TEXT:
        return iBeamCursor();
    case CURSOR_WAIT:
        return waitCursor();
    case CURSOR_HELP:
        return helpCursor();
    case CURSOR_VERTICAL_TEXT:
        return verticalTextCursor();
    case CURSOR_CELL:
        return cellCursor();
    case CURSOR_CONTEXT_MENU:
        return contextMenuCursor();
    case CURSOR_PROGRESS:
        return progressCursor();
    case CURSOR_NO_DROP:
        return noDropCursor();
    case CURSOR_ALIAS:
        return aliasCursor();
    case CURSOR_COPY:
        return copyCursor();
    case CURSOR_NONE:
        return noneCursor();
    case CURSOR_NOT_ALLOWED:
        return notAllowedCursor();
    case CURSOR_DEFAULT:
        return pointerCursor();
    case CURSOR_WEBKIT_ZOOM_IN:
        return zoomInCursor();
    case CURSOR_WEBKIT_ZOOM_OUT:
        return zoomOutCursor();
    case CURSOR_WEBKIT_GRAB:
        return grabCursor();
    case CURSOR_WEBKIT_GRABBING:
        return grabbingCursor();
    }
    return pointerCursor();
}

static IntPoint documentPointForWindowPoint(Frame* frame, const IntPoint& windowPoint)
{
    FrameView* view = frame->view();
    // FIXME: Is it really OK to use the wrong coordinates here when view is 0?
    // Historically the code would just crash; this is clearly no worse than that.
    return view ? view->windowToContents(windowPoint) : windowPoint;
}

bool EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
{
    RefPtr<FrameView> protector(m_frame->view());

    UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);

    cancelFakeMouseMoveEvent();
    m_mousePressed = true;
    m_capturesDragging = true;
    m_currentMousePosition = mouseEvent.pos();
    m_mouseDownTimestamp = mouseEvent.timestamp();
#if ENABLE(DRAG_SUPPORT)
    m_mouseDownMayStartDrag = false;
#endif
    m_mouseDownMayStartSelect = false;
    m_mouseDownMayStartAutoscroll = false;
    if (FrameView* view = m_frame->view())
        m_mouseDownPos = view->windowToContents(mouseEvent.pos());
    else {
        invalidateClick();
        return false;
    }
    m_mouseDownWasInSubframe = false;

#if ENABLE(COMPOSITED_FIXED_ELEMENTS)
    // Add IgnoreClipping because fixed position elements are moved only on the
    // UI thread.  Nodes in fixed position elements are clipped out by the view
    // without IgnoreClipping.
    HitTestRequest request(HitTestRequest::Active | HitTestRequest::IgnoreClipping);
#else
    HitTestRequest request(HitTestRequest::Active);
#endif
    // Save the document point we generate in case the window coordinate is invalidated by what happens
    // when we dispatch the event.
    IntPoint documentPoint = documentPointForWindowPoint(m_frame, mouseEvent.pos());
    MouseEventWithHitTestResults mev = m_frame->document()->prepareMouseEvent(request, documentPoint, mouseEvent);

    if (!mev.targetNode()) {
        invalidateClick();
        return false;
    }

    m_mousePressNode = mev.targetNode();

    if (InspectorInstrumentation::handleMousePress(m_frame->page())) {
        invalidateClick();
        return true;
    }

    Frame* subframe = subframeForHitTestResult(mev);
    if (subframe && passMousePressEventToSubframe(mev, subframe)) {
        // Start capturing future events for this frame.  We only do this if we didn't clear
        // the m_mousePressed flag, which may happen if an AppKit widget entered a modal event loop.
        m_capturesDragging = subframe->eventHandler()->capturesDragging();
        if (m_mousePressed && m_capturesDragging) {
            m_capturingMouseEventsNode = mev.targetNode();
            m_eventHandlerWillResetCapturingMouseEventsNode = true;
        }
        invalidateClick();
        return true;
    }

#if ENABLE(PAN_SCROLLING)
    Page* page = m_frame->page();
    if ((page && page->mainFrame()->eventHandler()->panScrollInProgress()) || m_autoscrollInProgress) {
        stopAutoscrollTimer();
        invalidateClick();
        return true;
    }
#endif

    m_clickCount = mouseEvent.clickCount();
    m_clickNode = mev.targetNode();

    if (FrameView* view = m_frame->view()) {
        RenderLayer* layer = m_clickNode->renderer() ? m_clickNode->renderer()->enclosingLayer() : 0;
        IntPoint p = view->windowToContents(mouseEvent.pos());
        if (layer && layer->isPointInResizeControl(p)) {
            layer->setInResizeMode(true);
            m_resizeLayer = layer;
            m_offsetFromResizeCorner = layer->offsetFromResizeCorner(p);
            invalidateClick();
            return true;
        }
    }

    m_frame->selection()->setCaretBlinkingSuspended(true);

    bool swallowEvent = dispatchMouseEvent(eventNames().mousedownEvent, mev.targetNode(), true, m_clickCount, mouseEvent, true);
    m_capturesDragging = !swallowEvent;

    // If the hit testing originally determined the event was in a scrollbar, refetch the MouseEventWithHitTestResults
    // in case the scrollbar widget was destroyed when the mouse event was handled.
    if (mev.scrollbar()) {
        const bool wasLastScrollBar = mev.scrollbar() == m_lastScrollbarUnderMouse.get();
        HitTestRequest request(HitTestRequest::ReadOnly | HitTestRequest::Active);
        mev = m_frame->document()->prepareMouseEvent(request, documentPoint, mouseEvent);
        if (wasLastScrollBar && mev.scrollbar() != m_lastScrollbarUnderMouse.get())
            m_lastScrollbarUnderMouse = 0;
    }

    if (swallowEvent) {
        // scrollbars should get events anyway, even disabled controls might be scrollable
        Scrollbar* scrollbar = mev.scrollbar();

        updateLastScrollbarUnderMouse(scrollbar, true);

        if (scrollbar)
            passMousePressEventToScrollbar(mev, scrollbar);
    } else {
        // Refetch the event target node if it currently is the shadow node inside an <input> element.
        // If a mouse event handler changes the input element type to one that has a widget associated,
        // we'd like to EventHandler::handleMousePressEvent to pass the event to the widget and thus the
        // event target node can't still be the shadow node.
        if (mev.targetNode()->isShadowRoot() && mev.targetNode()->shadowHost()->hasTagName(inputTag)) {
            HitTestRequest request(HitTestRequest::ReadOnly | HitTestRequest::Active);
            mev = m_frame->document()->prepareMouseEvent(request, documentPoint, mouseEvent);
        }

        FrameView* view = m_frame->view();
        Scrollbar* scrollbar = view ? view->scrollbarAtPoint(mouseEvent.pos()) : 0;
        if (!scrollbar)
            scrollbar = mev.scrollbar();

        updateLastScrollbarUnderMouse(scrollbar, true);

        if (scrollbar && passMousePressEventToScrollbar(mev, scrollbar))
            swallowEvent = true;
        else
            swallowEvent = handleMousePressEvent(mev);
    }

    return swallowEvent;
}

// This method only exists for platforms that don't know how to deliver
bool EventHandler::handleMouseDoubleClickEvent(const PlatformMouseEvent& mouseEvent)
{
    RefPtr<FrameView> protector(m_frame->view());

    UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);

    // We get this instead of a second mouse-up
    m_mousePressed = false;
    m_currentMousePosition = mouseEvent.pos();

    HitTestRequest request(HitTestRequest::Active);
    MouseEventWithHitTestResults mev = prepareMouseEvent(request, mouseEvent);
    Frame* subframe = subframeForHitTestResult(mev);
    if (m_eventHandlerWillResetCapturingMouseEventsNode)
        m_capturingMouseEventsNode = 0;
    if (subframe && passMousePressEventToSubframe(mev, subframe))
        return true;

    m_clickCount = mouseEvent.clickCount();
    bool swallowMouseUpEvent = dispatchMouseEvent(eventNames().mouseupEvent, mev.targetNode(), true, m_clickCount, mouseEvent, false);

    bool swallowClickEvent = mouseEvent.button() != RightButton && mev.targetNode() == m_clickNode && dispatchMouseEvent(eventNames().clickEvent, mev.targetNode(), true, m_clickCount, mouseEvent, true);

    if (m_lastScrollbarUnderMouse)
        swallowMouseUpEvent = m_lastScrollbarUnderMouse->mouseUp();

    bool swallowMouseReleaseEvent = !swallowMouseUpEvent && handleMouseReleaseEvent(mev);

    invalidateClick();

    return swallowMouseUpEvent || swallowClickEvent || swallowMouseReleaseEvent;
}

static RenderLayer* layerForNode(Node* node)
{
    if (!node)
        return 0;

    RenderObject* renderer = node->renderer();
    if (!renderer)
        return 0;

    RenderLayer* layer = renderer->enclosingLayer();
    if (!layer)
        return 0;

    return layer;
}

bool EventHandler::mouseMoved(const PlatformMouseEvent& event)
{
    HitTestResult hoveredNode = HitTestResult(IntPoint());
    bool result = handleMouseMoveEvent(event, &hoveredNode);

    Page* page = m_frame->page();
    if (!page)
        return result;

    if (RenderLayer* layer = layerForNode(hoveredNode.innerNode())) {
        if (page->containsScrollableArea(layer))
            layer->scrollAnimator()->mouseMovedInContentArea();
    }

    if (FrameView* frameView = m_frame->view())
        frameView->scrollAnimator()->mouseMovedInContentArea();

    hoveredNode.setToNonShadowAncestor();
    page->chrome()->mouseDidMoveOverElement(hoveredNode, event.modifierFlags());
    page->chrome()->setToolTip(hoveredNode);
    return result;
}

bool EventHandler::handleMouseMoveEvent(const PlatformMouseEvent& mouseEvent, HitTestResult* hoveredNode)
{
    // in Radar 3703768 we saw frequent crashes apparently due to the
    // part being null here, which seems impossible, so check for nil
    // but also assert so that we can try to figure this out in debug
    // builds, if it happens.
    ASSERT(m_frame);
    if (!m_frame)
        return false;

    RefPtr<FrameView> protector(m_frame->view());
    m_currentMousePosition = mouseEvent.pos();

    if (m_hoverTimer.isActive())
        m_hoverTimer.stop();

    cancelFakeMouseMoveEvent();

#if ENABLE(SVG)
    if (m_svgPan) {
        static_cast<SVGDocument*>(m_frame->document())->updatePan(m_currentMousePosition);
        return true;
    }
#endif

    if (m_frameSetBeingResized)
        return dispatchMouseEvent(eventNames().mousemoveEvent, m_frameSetBeingResized.get(), false, 0, mouseEvent, false);

    // Send events right to a scrollbar if the mouse is pressed.
    if (m_lastScrollbarUnderMouse && m_mousePressed)
        return m_lastScrollbarUnderMouse->mouseMoved(mouseEvent);

    // Treat mouse move events while the mouse is pressed as "read-only" in prepareMouseEvent
    // if we are allowed to select.
    // This means that :hover and :active freeze in the state they were in when the mouse
    // was pressed, rather than updating for nodes the mouse moves over as you hold the mouse down.
    HitTestRequest::HitTestRequestType hitType = HitTestRequest::MouseMove;
    if (m_mousePressed && m_mouseDownMayStartSelect)
        hitType |= HitTestRequest::ReadOnly;
    if (m_mousePressed)
        hitType |= HitTestRequest::Active;

#if ENABLE(TOUCH_EVENTS)
    // Treat any mouse move events as readonly if the user is currently touching the screen.
    if (m_touchPressed)
        hitType |= HitTestRequest::Active | HitTestRequest::ReadOnly;
#endif
    HitTestRequest request(hitType);
    MouseEventWithHitTestResults mev = prepareMouseEvent(request, mouseEvent);
    if (hoveredNode)
        *hoveredNode = mev.hitTestResult();

    Scrollbar* scrollbar = 0;

    if (m_resizeLayer && m_resizeLayer->inResizeMode())
        m_resizeLayer->resize(mouseEvent, m_offsetFromResizeCorner);
    else {
        if (FrameView* view = m_frame->view())
            scrollbar = view->scrollbarAtPoint(mouseEvent.pos());

        if (!scrollbar)
            scrollbar = mev.scrollbar();

        updateLastScrollbarUnderMouse(scrollbar, !m_mousePressed);
    }

    bool swallowEvent = false;
    RefPtr<Frame> newSubframe = m_capturingMouseEventsNode.get() ? subframeForTargetNode(m_capturingMouseEventsNode.get()) : subframeForHitTestResult(mev);

    // We want mouseouts to happen first, from the inside out.  First send a move event to the last subframe so that it will fire mouseouts.
    if (m_lastMouseMoveEventSubframe && m_lastMouseMoveEventSubframe->tree()->isDescendantOf(m_frame) && m_lastMouseMoveEventSubframe != newSubframe)
        passMouseMoveEventToSubframe(mev, m_lastMouseMoveEventSubframe.get());

    if (newSubframe) {
        // Update over/out state before passing the event to the subframe.
        updateMouseEventTargetNode(mev.targetNode(), mouseEvent, true);

        // Event dispatch in updateMouseEventTargetNode may have caused the subframe of the target
        // node to be detached from its FrameView, in which case the event should not be passed.
        if (newSubframe->view())
            swallowEvent |= passMouseMoveEventToSubframe(mev, newSubframe.get(), hoveredNode);
    } else {
        if (scrollbar && !m_mousePressed)
            scrollbar->mouseMoved(mouseEvent); // Handle hover effects on platforms that support visual feedback on scrollbar hovering.
        if (Page* page = m_frame->page()) {
            if ((!m_resizeLayer || !m_resizeLayer->inResizeMode()) && !page->mainFrame()->eventHandler()->panScrollInProgress()) {
                // Plugins set cursor on their own. The only case WebKit intervenes is resetting cursor to arrow on mouse enter,
                // in case the particular plugin doesn't manipulate cursor at all. Thus,  even a CSS cursor set on body has no
                // effect on plugins (which matches Firefox).
                bool overPluginElement = false;
                if (mev.targetNode() && mev.targetNode()->isHTMLElement()) {
                    HTMLElement* el = toHTMLElement(mev.targetNode());
                    overPluginElement = el->hasTagName(appletTag) || el->hasTagName(objectTag) || el->hasTagName(embedTag);
                }
                if (!overPluginElement) {
                    if (FrameView* view = m_frame->view())
                        view->setCursor(selectCursor(mev, scrollbar));
                }
            }
        }
    }

    m_lastMouseMoveEventSubframe = newSubframe;

    if (swallowEvent)
        return true;

    swallowEvent = dispatchMouseEvent(eventNames().mousemoveEvent, mev.targetNode(), false, 0, mouseEvent, true);
#if ENABLE(DRAG_SUPPORT)
    if (!swallowEvent)
        swallowEvent = handleMouseDraggedEvent(mev);
#endif // ENABLE(DRAG_SUPPORT)

    return swallowEvent;
}

void EventHandler::invalidateClick()
{
    m_clickCount = 0;
    m_clickNode = 0;
}

bool EventHandler::handleMouseReleaseEvent(const PlatformMouseEvent& mouseEvent)
{
    RefPtr<FrameView> protector(m_frame->view());

    UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);

#if ENABLE(PAN_SCROLLING)
    if (mouseEvent.button() == MiddleButton)
        m_panScrollButtonPressed = false;
    if (m_springLoadedPanScrollInProgress)
        stopAutoscrollTimer();
#endif

    m_mousePressed = false;
    m_currentMousePosition = mouseEvent.pos();

#if ENABLE(SVG)
    if (m_svgPan) {
        m_svgPan = false;
        static_cast<SVGDocument*>(m_frame->document())->updatePan(m_currentMousePosition);
        return true;
    }
#endif

    if (m_frameSetBeingResized)
        return dispatchMouseEvent(eventNames().mouseupEvent, m_frameSetBeingResized.get(), true, m_clickCount, mouseEvent, false);

    if (m_lastScrollbarUnderMouse) {
        invalidateClick();
        return m_lastScrollbarUnderMouse->mouseUp();
    }

#if ENABLE(COMPOSITED_FIXED_ELEMENTS)
    // Add IgnoreClipping because fixed position elements are moved only on the
    // UI thread.  Nodes in fixed position elements are clipped out by the view
    // without IgnoreClipping.
    HitTestRequest request(HitTestRequest::MouseUp | HitTestRequest::IgnoreClipping);
#else
    HitTestRequest request(HitTestRequest::MouseUp);
#endif
    MouseEventWithHitTestResults mev = prepareMouseEvent(request, mouseEvent);
    Frame* subframe = m_capturingMouseEventsNode.get() ? subframeForTargetNode(m_capturingMouseEventsNode.get()) : subframeForHitTestResult(mev);
    if (m_eventHandlerWillResetCapturingMouseEventsNode)
        m_capturingMouseEventsNode = 0;
    if (subframe && passMouseReleaseEventToSubframe(mev, subframe))
        return true;

    bool swallowMouseUpEvent = dispatchMouseEvent(eventNames().mouseupEvent, mev.targetNode(), true, m_clickCount, mouseEvent, false);

    bool swallowClickEvent = m_clickCount > 0 && mouseEvent.button() != RightButton && mev.targetNode() == m_clickNode && dispatchMouseEvent(eventNames().clickEvent, mev.targetNode(), true, m_clickCount, mouseEvent, true);

    if (m_resizeLayer) {
        m_resizeLayer->setInResizeMode(false);
        m_resizeLayer = 0;
    }

    bool swallowMouseReleaseEvent = false;
    if (!swallowMouseUpEvent)
        swallowMouseReleaseEvent = handleMouseReleaseEvent(mev);

    invalidateClick();

    return swallowMouseUpEvent || swallowClickEvent || swallowMouseReleaseEvent;
}

#if ENABLE(DRAG_SUPPORT)
bool EventHandler::dispatchDragEvent(const AtomicString& eventType, Node* dragTarget, const PlatformMouseEvent& event, Clipboard* clipboard)
{
    FrameView* view = m_frame->view();

    // FIXME: We might want to dispatch a dragleave even if the view is gone.
    if (!view)
        return false;

    view->resetDeferredRepaintDelay();
    IntPoint contentsPos = view->windowToContents(event.pos());

    RefPtr<MouseEvent> me = MouseEvent::create(eventType,
        true, true, m_frame->document()->defaultView(),
        0, event.globalX(), event.globalY(), contentsPos.x(), contentsPos.y(),
        event.ctrlKey(), event.altKey(), event.shiftKey(), event.metaKey(),
        0, 0, clipboard);

    ExceptionCode ec;
    dragTarget->dispatchEvent(me.get(), ec);
    return me->defaultPrevented();
}

bool EventHandler::canHandleDragAndDropForTarget(DragAndDropHandleType type, Node* target, const PlatformMouseEvent& event, Clipboard* clipboard, bool* accepted)
{
    bool canHandle = false;
    bool wasAccepted = false;

    if (target->hasTagName(frameTag) || target->hasTagName(iframeTag)) {
        Frame* frame = static_cast<HTMLFrameElementBase*>(target)->contentFrame();
        if (frame) {
            switch (type) {
            case UpdateDragAndDrop:
                wasAccepted = frame->eventHandler()->updateDragAndDrop(event, clipboard);
                break;
            case CancelDragAndDrop:
                frame->eventHandler()->cancelDragAndDrop(event, clipboard);
                break;
            case PerformDragAndDrop:
                wasAccepted = frame->eventHandler()->performDragAndDrop(event, clipboard);
                break;
            }
        }
    } else
        canHandle = true;

    if (accepted)
        *accepted = wasAccepted;

    return canHandle;
}

bool EventHandler::updateDragAndDrop(const PlatformMouseEvent& event, Clipboard* clipboard)
{
    bool accept = false;

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

    HitTestRequest request(HitTestRequest::ReadOnly);
    MouseEventWithHitTestResults mev = prepareMouseEvent(request, event);

    // Drag events should never go to text nodes (following IE, and proper mouseover/out dispatch)
    Node* newTarget = mev.targetNode();
    if (newTarget && newTarget->isTextNode())
        newTarget = newTarget->parentNode();
    if (newTarget)
        newTarget = newTarget->shadowAncestorNode();

    if (m_dragTarget != newTarget) {
        // FIXME: this ordering was explicitly chosen to match WinIE. However,
        // it is sometimes incorrect when dragging within subframes, as seen with
        // LayoutTests/fast/events/drag-in-frames.html.
        //
        // Moreover, this ordering conforms to section 7.9.4 of the HTML 5 spec. <http://dev.w3.org/html5/spec/Overview.html#drag-and-drop-processing-model>.
        if (newTarget && canHandleDragAndDropForTarget(UpdateDragAndDrop, newTarget, event, clipboard, &accept)) {
            // As per section 7.9.4 of the HTML 5 spec., we must always fire a drag event before firing a dragenter, dragleave, or dragover event.
            if (dragState().m_dragSrc && dragState().m_dragSrcMayBeDHTML) {
                // for now we don't care if event handler cancels default behavior, since there is none
                dispatchDragSrcEvent(eventNames().dragEvent, event);
            }
            accept = dispatchDragEvent(eventNames().dragenterEvent, newTarget, event, clipboard);
        }

        if (m_dragTarget && canHandleDragAndDropForTarget(UpdateDragAndDrop, m_dragTarget.get(), event, clipboard, &accept))
            dispatchDragEvent(eventNames().dragleaveEvent, m_dragTarget.get(), event, clipboard);

        if (newTarget) {
            // We do not explicitly call dispatchDragEvent here because it could ultimately result in the appearance that
            // two dragover events fired. So, we mark that we should only fire a dragover event on the next call to this function.
            m_shouldOnlyFireDragOverEvent = true;
        }
    } else {
        if (newTarget && canHandleDragAndDropForTarget(UpdateDragAndDrop, newTarget, event, clipboard, &accept)) {
            // Note, when dealing with sub-frames, we may need to fire only a dragover event as a drag event may have been fired earlier.
            if (!m_shouldOnlyFireDragOverEvent && dragState().m_dragSrc && dragState().m_dragSrcMayBeDHTML) {
                // for now we don't care if event handler cancels default behavior, since there is none
                dispatchDragSrcEvent(eventNames().dragEvent, event);
            }
            accept = dispatchDragEvent(eventNames().dragoverEvent, newTarget, event, clipboard);
            m_shouldOnlyFireDragOverEvent = false;
        }
    }
    m_dragTarget = newTarget;

    return accept;
}

void EventHandler::cancelDragAndDrop(const PlatformMouseEvent& event, Clipboard* clipboard)
{
    if (m_dragTarget && canHandleDragAndDropForTarget(CancelDragAndDrop, m_dragTarget.get(), event, clipboard)) {
        if (dragState().m_dragSrc && dragState().m_dragSrcMayBeDHTML)
            dispatchDragSrcEvent(eventNames().dragEvent, event);
        dispatchDragEvent(eventNames().dragleaveEvent, m_dragTarget.get(), event, clipboard);
    }
    clearDragState();
}

bool EventHandler::performDragAndDrop(const PlatformMouseEvent& event, Clipboard* clipboard)
{
    bool accept = false;
    if (m_dragTarget && canHandleDragAndDropForTarget(PerformDragAndDrop, m_dragTarget.get(), event, clipboard, &accept))
        dispatchDragEvent(eventNames().dropEvent, m_dragTarget.get(), event, clipboard);
    clearDragState();
    return accept;
}

void EventHandler::clearDragState()
{
    m_dragTarget = 0;
    m_capturingMouseEventsNode = 0;
    m_shouldOnlyFireDragOverEvent = false;
#if PLATFORM(MAC)
    m_sendingEventToSubview = false;
#endif
}
#endif // ENABLE(DRAG_SUPPORT)

#if PLATFORM(ANDROID) && ENABLE(TOUCH_EVENTS)
void EventHandler::setCapturingTouchEventsNode(PassRefPtr<Node> n)
{
    m_capturingTouchEventsNode = n;
}
#endif

void EventHandler::setCapturingMouseEventsNode(PassRefPtr<Node> n)
{
    m_capturingMouseEventsNode = n;
    m_eventHandlerWillResetCapturingMouseEventsNode = false;
}

MouseEventWithHitTestResults EventHandler::prepareMouseEvent(const HitTestRequest& request, const PlatformMouseEvent& mev)
{
    ASSERT(m_frame);
    ASSERT(m_frame->document());

    return m_frame->document()->prepareMouseEvent(request, documentPointForWindowPoint(m_frame, mev.pos()), mev);
}

#if ENABLE(SVG)
static inline SVGElementInstance* instanceAssociatedWithShadowTreeElement(Node* referenceNode)
{
    if (!referenceNode || !referenceNode->isSVGElement())
        return 0;

    Node* shadowTreeElement = referenceNode->shadowTreeRootNode();
    if (!shadowTreeElement)
        return 0;

    Element* shadowTreeParentElement = shadowTreeElement->shadowHost();
    if (!shadowTreeParentElement)
        return 0;

    ASSERT(shadowTreeParentElement->hasTagName(useTag));
    return static_cast<SVGUseElement*>(shadowTreeParentElement)->instanceForShadowTreeElement(referenceNode);
}
#endif

void EventHandler::updateMouseEventTargetNode(Node* targetNode, const PlatformMouseEvent& mouseEvent, bool fireMouseOverOut)
{
    Node* result = targetNode;

    // If we're capturing, we always go right to that node.
    if (m_capturingMouseEventsNode)
        result = m_capturingMouseEventsNode.get();
    else {
        // If the target node is a text node, dispatch on the parent node - rdar://4196646
        if (result && result->isTextNode())
            result = result->parentNode();
    }
    m_nodeUnderMouse = result;
#if ENABLE(SVG)
    m_instanceUnderMouse = instanceAssociatedWithShadowTreeElement(result);

    // <use> shadow tree elements may have been recloned, update node under mouse in any case
    if (m_lastInstanceUnderMouse) {
        SVGElement* lastCorrespondingElement = m_lastInstanceUnderMouse->correspondingElement();
        SVGElement* lastCorrespondingUseElement = m_lastInstanceUnderMouse->correspondingUseElement();

        if (lastCorrespondingElement && lastCorrespondingUseElement) {
            HashSet<SVGElementInstance*> instances = lastCorrespondingElement->instancesForElement();

            // Locate the recloned shadow tree element for our corresponding instance
            HashSet<SVGElementInstance*>::iterator end = instances.end();
            for (HashSet<SVGElementInstance*>::iterator it = instances.begin(); it != end; ++it) {
                SVGElementInstance* instance = (*it);
                ASSERT(instance->correspondingElement() == lastCorrespondingElement);

                if (instance == m_lastInstanceUnderMouse)
                    continue;

                if (instance->correspondingUseElement() != lastCorrespondingUseElement)
                    continue;

                SVGElement* shadowTreeElement = instance->shadowTreeElement();
                if (!shadowTreeElement->inDocument() || m_lastNodeUnderMouse == shadowTreeElement)
                    continue;

                m_lastNodeUnderMouse = shadowTreeElement;
                m_lastInstanceUnderMouse = instance;
                break;
            }
        }
    }
#endif

    // Fire mouseout/mouseover if the mouse has shifted to a different node.
    if (fireMouseOverOut) {
        RenderLayer* layerForLastNode = layerForNode(m_lastNodeUnderMouse.get());
        RenderLayer* layerForNodeUnderMouse = layerForNode(m_nodeUnderMouse.get());
        Page* page = m_frame->page();

        if (m_lastNodeUnderMouse && (!m_nodeUnderMouse || m_nodeUnderMouse->document() != m_frame->document())) {
            // The mouse has moved between frames.
            if (Frame* frame = m_lastNodeUnderMouse->document()->frame()) {
                if (FrameView* frameView = frame->view())
                    frameView->scrollAnimator()->mouseExitedContentArea();
            }
        } else if (page && (layerForLastNode && (!layerForNodeUnderMouse || layerForNodeUnderMouse != layerForLastNode))) {
            // The mouse has moved between layers.
            if (page->containsScrollableArea(layerForLastNode))
                layerForLastNode->scrollAnimator()->mouseExitedContentArea();
        }

        if (m_nodeUnderMouse && (!m_lastNodeUnderMouse || m_lastNodeUnderMouse->document() != m_frame->document())) {
            // The mouse has moved between frames.
            if (Frame* frame = m_nodeUnderMouse->document()->frame()) {
                if (FrameView* frameView = frame->view())
                    frameView->scrollAnimator()->mouseEnteredContentArea();
            }
        } else if (page && (layerForNodeUnderMouse && (!layerForLastNode || layerForNodeUnderMouse != layerForLastNode))) {
            // The mouse has moved between layers.
            if (page->containsScrollableArea(layerForNodeUnderMouse))
                layerForNodeUnderMouse->scrollAnimator()->mouseEnteredContentArea();
        }

        if (m_lastNodeUnderMouse && m_lastNodeUnderMouse->document() != m_frame->document()) {
            m_lastNodeUnderMouse = 0;
            m_lastScrollbarUnderMouse = 0;
#if ENABLE(SVG)
            m_lastInstanceUnderMouse = 0;
#endif
        }

        if (m_lastNodeUnderMouse != m_nodeUnderMouse) {
            // send mouseout event to the old node
            if (m_lastNodeUnderMouse)
                m_lastNodeUnderMouse->dispatchMouseEvent(mouseEvent, eventNames().mouseoutEvent, 0, m_nodeUnderMouse.get());
            // send mouseover event to the new node
            if (m_nodeUnderMouse)
                m_nodeUnderMouse->dispatchMouseEvent(mouseEvent, eventNames().mouseoverEvent, 0, m_lastNodeUnderMouse.get());
        }
        m_lastNodeUnderMouse = m_nodeUnderMouse;
#if ENABLE(SVG)
        m_lastInstanceUnderMouse = instanceAssociatedWithShadowTreeElement(m_nodeUnderMouse.get());
#endif
    }
}

bool EventHandler::dispatchMouseEvent(const AtomicString& eventType, Node* targetNode, bool /*cancelable*/, int clickCount, const PlatformMouseEvent& mouseEvent, bool setUnder)
{
    if (FrameView* view = m_frame->view())
        view->resetDeferredRepaintDelay();

    updateMouseEventTargetNode(targetNode, mouseEvent, setUnder);

    bool swallowEvent = false;

    if (m_nodeUnderMouse)
        swallowEvent = m_nodeUnderMouse->dispatchMouseEvent(mouseEvent, eventType, clickCount);

    if (!swallowEvent && eventType == eventNames().mousedownEvent) {

        // If clicking on a frame scrollbar, do not mess up with content focus.
        if (FrameView* view = m_frame->view()) {
            if (view->scrollbarAtPoint(mouseEvent.pos()))
                return false;
        }

        // The layout needs to be up to date to determine if an element is focusable.
        m_frame->document()->updateLayoutIgnorePendingStylesheets();

        // Blur current focus node when a link/button is clicked; this
        // is expected by some sites that rely on onChange handlers running
        // from form fields before the button click is processed.
        Node* node = m_nodeUnderMouse.get();

        // Walk up the DOM tree to search for a node to focus.
        while (node) {
            if (node->isMouseFocusable()) {
                // To fix <rdar://problem/4895428> Can't drag selected ToDo, we don't focus a
                // node on mouse down if it's selected and inside a focused node. It will be
                // focused if the user does a mouseup over it, however, because the mouseup
                // will set a selection inside it, which will call setFocuseNodeIfNeeded.
                ExceptionCode ec = 0;
                Node* n = node->isShadowRoot() ? node->shadowHost() : node;
                if (m_frame->selection()->isRange()
                    && m_frame->selection()->toNormalizedRange()->compareNode(n, ec) == Range::NODE_INSIDE
                    && n->isDescendantOf(m_frame->document()->focusedNode()))
                    return false;

                break;
            }
            node = node->parentOrHostNode();
        }

        // If focus shift is blocked, we eat the event.  Note we should never clear swallowEvent
        // if the page already set it (e.g., by canceling default behavior).
        if (Page* page = m_frame->page()) {
            if (node && node->isMouseFocusable()) {
                if (!page->focusController()->setFocusedNode(node, m_frame))
                    swallowEvent = true;
            } else if (!node || !node->focused()) {
                if (!page->focusController()->setFocusedNode(0, m_frame))
                    swallowEvent = true;
            }
        }
    }

    return swallowEvent;
}

#if !PLATFORM(GTK) && !(PLATFORM(CHROMIUM) && (OS(LINUX) || OS(FREEBSD)))
bool EventHandler::shouldTurnVerticalTicksIntoHorizontal(const HitTestResult&) const
{
    return false;
}
#endif

bool EventHandler::handleWheelEvent(PlatformWheelEvent& e)
{
    Document* doc = m_frame->document();

    RenderObject* docRenderer = doc->renderer();
    if (!docRenderer)
        return false;

    RefPtr<FrameView> protector(m_frame->view());

    FrameView* view = m_frame->view();
    if (!view)
        return false;
    setFrameWasScrolledByUser();
    IntPoint vPoint = view->windowToContents(e.pos());

    Node* node;
    bool isOverWidget;

    HitTestRequest request(HitTestRequest::ReadOnly);
    HitTestResult result(vPoint);
    doc->renderView()->layer()->hitTest(request, result);

    if (m_useLatchedWheelEventNode) {
        if (!m_latchedWheelEventNode) {
            m_latchedWheelEventNode = result.innerNode();
            m_widgetIsLatched = result.isOverWidget();
        }

        node = m_latchedWheelEventNode.get();
        isOverWidget = m_widgetIsLatched;
    } else {
        if (m_latchedWheelEventNode)
            m_latchedWheelEventNode = 0;
        if (m_previousWheelScrolledNode)
            m_previousWheelScrolledNode = 0;

        node = result.innerNode();
        isOverWidget = result.isOverWidget();
    }

    if (shouldTurnVerticalTicksIntoHorizontal(result))
        e.turnVerticalTicksIntoHorizontal();

    if (node) {
        // Figure out which view to send the event to.
        RenderObject* target = node->renderer();

        if (isOverWidget && target && target->isWidget()) {
            Widget* widget = toRenderWidget(target)->widget();
            if (widget && passWheelEventToWidget(e, widget)) {
                e.accept();
                return true;
            }
        }

        node = node->shadowAncestorNode();
        node->dispatchWheelEvent(e);
        if (e.isAccepted())
            return true;
    }

    if (e.isAccepted())
        return true;

    view = m_frame->view();
    if (!view)
        return false;

    view->wheelEvent(e);
    return e.isAccepted();
}

void EventHandler::defaultWheelEventHandler(Node* startNode, WheelEvent* wheelEvent)
{
    if (!startNode || !wheelEvent)
        return;

    Node* stopNode = m_previousWheelScrolledNode.get();

    // Break up into two scrolls if we need to.  Diagonal movement on
    // a MacBook pro is an example of a 2-dimensional mouse wheel event (where both deltaX and deltaY can be set).
    if (scrollNode(wheelEvent->rawDeltaX(), wheelEvent->granularity(), ScrollLeft, ScrollRight, startNode, &stopNode))
        wheelEvent->setDefaultHandled();

    if (scrollNode(wheelEvent->rawDeltaY(), wheelEvent->granularity(), ScrollUp, ScrollDown, startNode, &stopNode))
        wheelEvent->setDefaultHandled();

    if (!m_useLatchedWheelEventNode)
        m_previousWheelScrolledNode = stopNode;
}

#if ENABLE(GESTURE_EVENTS)
bool EventHandler::handleGestureEvent(const PlatformGestureEvent& gestureEvent)
{
    // FIXME: This should hit test and go to the correct subframe rather than
    // always sending gestures to the main frame only. We should also ensure
    // that if a frame gets a gesture begin gesture, it gets the corresponding
    // end gesture as well.

    FrameView* view = m_frame->view();
    if (!view)
        return false;

    view->handleGestureEvent(gestureEvent);
    return true;
}
#endif

#if ENABLE(CONTEXT_MENUS)
bool EventHandler::sendContextMenuEvent(const PlatformMouseEvent& event)
{
    Document* doc = m_frame->document();
    FrameView* v = m_frame->view();
    if (!v)
        return false;

    bool swallowEvent;
    IntPoint viewportPos = v->windowToContents(event.pos());
    HitTestRequest request(HitTestRequest::Active);
    MouseEventWithHitTestResults mev = doc->prepareMouseEvent(request, viewportPos, event);

    if (m_frame->editor()->behavior().shouldSelectOnContextualMenuClick()
        && !m_frame->selection()->contains(viewportPos)
        // FIXME: In the editable case, word selection sometimes selects content that isn't underneath the mouse.
        // If the selection is non-editable, we do word selection to make it easier to use the contextual menu items
        // available for text selections.  But only if we're above text.
        && (m_frame->selection()->isContentEditable() || (mev.targetNode() && mev.targetNode()->isTextNode()))) {
        m_mouseDownMayStartSelect = true; // context menu events are always allowed to perform a selection
        selectClosestWordOrLinkFromMouseEvent(mev);
    }

    swallowEvent = dispatchMouseEvent(eventNames().contextmenuEvent, mev.targetNode(), true, 0, event, false);

    return swallowEvent;
}

bool EventHandler::sendContextMenuEventForKey()
{
    FrameView* view = m_frame->view();
    if (!view)
        return false;

    Document* doc = m_frame->document();
    if (!doc)
        return false;

    static const int kContextMenuMargin = 1;

#if OS(WINDOWS) && !OS(WINCE)
    int rightAligned = ::GetSystemMetrics(SM_MENUDROPALIGNMENT);
#else
    int rightAligned = 0;
#endif
    IntPoint location;

    Node* focusedNode = doc->focusedNode();
    SelectionController* selectionController = m_frame->selection();
    Position start = selectionController->selection().start();

    if (start.deprecatedNode() && (selectionController->rootEditableElement() || selectionController->isRange())) {
        RefPtr<Range> selection = selectionController->toNormalizedRange();
        IntRect firstRect = m_frame->editor()->firstRectForRange(selection.get());

        int x = rightAligned ? firstRect.maxX() : firstRect.x();
        location = IntPoint(x, firstRect.maxY());
    } else if (focusedNode) {
        RenderBoxModelObject* box = focusedNode->renderBoxModelObject();
        if (!box)
            return false;
        IntRect clippedRect = box->absoluteClippedOverflowRect();
        location = IntPoint(clippedRect.x(), clippedRect.maxY() - 1);
    } else {
        location = IntPoint(
            rightAligned ? view->contentsWidth() - kContextMenuMargin : kContextMenuMargin,
            kContextMenuMargin);
    }

    m_frame->view()->setCursor(pointerCursor());

    IntPoint position = view->contentsToWindow(location);
    IntPoint globalPosition = view->contentsToScreen(IntRect(location, IntSize())).location();

    Node* targetNode = doc->focusedNode();
    if (!targetNode)
        targetNode = doc;

    // Use the focused node as the target for hover and active.
    HitTestResult result(position);
    result.setInnerNode(targetNode);
    HitTestRequest request(HitTestRequest::Active);
    doc->renderView()->layer()->updateHoverActiveState(request, result);
    doc->updateStyleIfNeeded();

    // The contextmenu event is a mouse event even when invoked using the keyboard.
    // This is required for web compatibility.

#if OS(WINDOWS)
    MouseEventType eventType = MouseEventReleased;
#else
    MouseEventType eventType = MouseEventPressed;
#endif

    PlatformMouseEvent mouseEvent(position, globalPosition, RightButton, eventType, 1, false, false, false, false, WTF::currentTime());

    return dispatchMouseEvent(eventNames().contextmenuEvent, targetNode, true, 0, mouseEvent, false);
}

#endif // ENABLE(CONTEXT_MENUS)

void EventHandler::scheduleHoverStateUpdate()
{
    if (!m_hoverTimer.isActive())
        m_hoverTimer.startOneShot(0);
}

void EventHandler::dispatchFakeMouseMoveEventSoon()
{
    if (m_mousePressed)
        return;

    if (!m_fakeMouseMoveEventTimer.isActive())
        m_fakeMouseMoveEventTimer.startOneShot(fakeMouseMoveInterval);
}

void EventHandler::dispatchFakeMouseMoveEventSoonInQuad(const FloatQuad& quad)
{
    FrameView* view = m_frame->view();
    if (!view)
        return;

    if (m_mousePressed || !quad.containsPoint(view->windowToContents(m_currentMousePosition)))
        return;

    if (!m_fakeMouseMoveEventTimer.isActive())
        m_fakeMouseMoveEventTimer.startOneShot(fakeMouseMoveInterval);
}

void EventHandler::cancelFakeMouseMoveEvent()
{
    m_fakeMouseMoveEventTimer.stop();
}

void EventHandler::fakeMouseMoveEventTimerFired(Timer<EventHandler>* timer)
{
    ASSERT_UNUSED(timer, timer == &m_fakeMouseMoveEventTimer);
    ASSERT(!m_mousePressed);

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

    bool shiftKey;
    bool ctrlKey;
    bool altKey;
    bool metaKey;
    PlatformKeyboardEvent::getCurrentModifierState(shiftKey, ctrlKey, altKey, metaKey);
    IntPoint globalPoint = view->contentsToScreen(IntRect(view->windowToContents(m_currentMousePosition), IntSize())).location();
    PlatformMouseEvent fakeMouseMoveEvent(m_currentMousePosition, globalPoint, NoButton, MouseEventMoved, 0, shiftKey, ctrlKey, altKey, metaKey, currentTime());
    mouseMoved(fakeMouseMoveEvent);
}

// Whether or not a mouse down can begin the creation of a selection.  Fires the selectStart event.
bool EventHandler::canMouseDownStartSelect(Node* node)
{
    if (!node || !node->renderer())
        return true;

    // Some controls and images can't start a select on a mouse down.
    if (!node->canStartSelection())
        return false;

    return node->dispatchEvent(Event::create(eventNames().selectstartEvent, true, true));
}

#if ENABLE(DRAG_SUPPORT)
bool EventHandler::canMouseDragExtendSelect(Node* node)
{
    if (!node || !node->renderer())
        return true;

    return node->dispatchEvent(Event::create(eventNames().selectstartEvent, true, true));
}
#endif // ENABLE(DRAG_SUPPORT)

void EventHandler::setResizingFrameSet(HTMLFrameSetElement* frameSet)
{
    m_frameSetBeingResized = frameSet;
}

void EventHandler::resizeLayerDestroyed()
{
    ASSERT(m_resizeLayer);
    m_resizeLayer = 0;
}

void EventHandler::hoverTimerFired(Timer<EventHandler>*)
{
    m_hoverTimer.stop();

    ASSERT(m_frame);
    ASSERT(m_frame->document());

    if (RenderView* renderer = m_frame->contentRenderer()) {
        if (FrameView* view = m_frame->view()) {
            HitTestRequest request(HitTestRequest::MouseMove);
            HitTestResult result(view->windowToContents(m_currentMousePosition));
            renderer->layer()->hitTest(request, result);
            m_frame->document()->updateStyleIfNeeded();
        }
    }
}

static Node* eventTargetNodeForDocument(Document* doc)
{
    if (!doc)
        return 0;
    Node* node = doc->focusedNode();
#if defined(ANDROID_PLUGINS)
    if (!node && doc->frame() && doc->frame()->view())
        node = android::WebViewCore::getWebViewCore(doc->frame()->view())
                                     ->cursorNodeIsPlugin();
#else
    if (!node && doc->isPluginDocument()) {
        PluginDocument* pluginDocument = static_cast<PluginDocument*>(doc);
        node =  pluginDocument->pluginNode();
    }
#endif
    if (!node && doc->isHTMLDocument())
        node = doc->body();
    if (!node)
        node = doc->documentElement();
    return node;
}

bool EventHandler::handleAccessKey(const PlatformKeyboardEvent& evt)
{
    // FIXME: Ignoring the state of Shift key is what neither IE nor Firefox do.
    // IE matches lower and upper case access keys regardless of Shift key state - but if both upper and
    // lower case variants are present in a document, the correct element is matched based on Shift key state.
    // Firefox only matches an access key if Shift is not pressed, and does that case-insensitively.
    ASSERT(!(accessKeyModifiers() & PlatformKeyboardEvent::ShiftKey));
    if ((evt.modifiers() & ~PlatformKeyboardEvent::ShiftKey) != accessKeyModifiers())
        return false;
    String key = evt.unmodifiedText();
    Element* elem = m_frame->document()->getElementByAccessKey(key.lower());
    if (!elem)
        return false;
    elem->accessKeyAction(false);
    return true;
}

#if !PLATFORM(MAC)
bool EventHandler::needsKeyboardEventDisambiguationQuirks() const
{
    return false;
}
#endif

bool EventHandler::keyEvent(const PlatformKeyboardEvent& initialKeyEvent)
{
    RefPtr<FrameView> protector(m_frame->view());

#if ENABLE(PAN_SCROLLING)
    if (Page* page = m_frame->page()) {
        if (page->mainFrame()->eventHandler()->panScrollInProgress() || m_autoscrollInProgress) {
            // If a key is pressed while the autoscroll/panScroll is in progress then we want to stop
            if (initialKeyEvent.type() == PlatformKeyboardEvent::KeyDown || initialKeyEvent.type() == PlatformKeyboardEvent::RawKeyDown)
                stopAutoscrollTimer();

            // If we were in autoscroll/panscroll mode, we swallow the key event
            return true;
        }
    }
#endif

    // Check for cases where we are too early for events -- possible unmatched key up
    // from pressing return in the location bar.
    RefPtr<Node> node = eventTargetNodeForDocument(m_frame->document());
    if (!node)
        return false;

    UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);
    UserTypingGestureIndicator typingGestureIndicator(m_frame);

    if (FrameView* view = m_frame->view())
        view->resetDeferredRepaintDelay();

    // FIXME: what is this doing here, in keyboard event handler?
    m_frame->loader()->resetMultipleFormSubmissionProtection();

    // In IE, access keys are special, they are handled after default keydown processing, but cannot be canceled - this is hard to match.
    // On Mac OS X, we process them before dispatching keydown, as the default keydown handler implements Emacs key bindings, which may conflict
    // with access keys. Then we dispatch keydown, but suppress its default handling.
    // On Windows, WebKit explicitly calls handleAccessKey() instead of dispatching a keypress event for WM_SYSCHAR messages.
    // Other platforms currently match either Mac or Windows behavior, depending on whether they send combined KeyDown events.
    bool matchedAnAccessKey = false;
    if (initialKeyEvent.type() == PlatformKeyboardEvent::KeyDown)
        matchedAnAccessKey = handleAccessKey(initialKeyEvent);

    // FIXME: it would be fair to let an input method handle KeyUp events before DOM dispatch.
    if (initialKeyEvent.type() == PlatformKeyboardEvent::KeyUp || initialKeyEvent.type() == PlatformKeyboardEvent::Char)
        return !node->dispatchKeyEvent(initialKeyEvent);

    bool backwardCompatibilityMode = needsKeyboardEventDisambiguationQuirks();

    ExceptionCode ec;
    PlatformKeyboardEvent keyDownEvent = initialKeyEvent;
    if (keyDownEvent.type() != PlatformKeyboardEvent::RawKeyDown)
        keyDownEvent.disambiguateKeyDownEvent(PlatformKeyboardEvent::RawKeyDown, backwardCompatibilityMode);
    RefPtr<KeyboardEvent> keydown = KeyboardEvent::create(keyDownEvent, m_frame->document()->defaultView());
    if (matchedAnAccessKey)
        keydown->setDefaultPrevented(true);
    keydown->setTarget(node);

    if (initialKeyEvent.type() == PlatformKeyboardEvent::RawKeyDown) {
        node->dispatchEvent(keydown, ec);
        // If frame changed as a result of keydown dispatch, then return true to avoid sending a subsequent keypress message to the new frame.
        bool changedFocusedFrame = m_frame->page() && m_frame != m_frame->page()->focusController()->focusedOrMainFrame();
        return keydown->defaultHandled() || keydown->defaultPrevented() || changedFocusedFrame;
    }

    // Run input method in advance of DOM event handling.  This may result in the IM
    // modifying the page prior the keydown event, but this behaviour is necessary
    // in order to match IE:
    // 1. preventing default handling of keydown and keypress events has no effect on IM input;
    // 2. if an input method handles the event, its keyCode is set to 229 in keydown event.
    m_frame->editor()->handleInputMethodKeydown(keydown.get());

    bool handledByInputMethod = keydown->defaultHandled();

    if (handledByInputMethod) {
        keyDownEvent.setWindowsVirtualKeyCode(CompositionEventKeyCode);
        keydown = KeyboardEvent::create(keyDownEvent, m_frame->document()->defaultView());
        keydown->setTarget(node);
        keydown->setDefaultHandled();
    }

    node->dispatchEvent(keydown, ec);
    // If frame changed as a result of keydown dispatch, then return early to avoid sending a subsequent keypress message to the new frame.
    bool changedFocusedFrame = m_frame->page() && m_frame != m_frame->page()->focusController()->focusedOrMainFrame();
    bool keydownResult = keydown->defaultHandled() || keydown->defaultPrevented() || changedFocusedFrame;
    if (handledByInputMethod || (keydownResult && !backwardCompatibilityMode))
        return keydownResult;

    // Focus may have changed during keydown handling, so refetch node.
    // But if we are dispatching a fake backward compatibility keypress, then we pretend that the keypress happened on the original node.
    if (!keydownResult) {
        node = eventTargetNodeForDocument(m_frame->document());
        if (!node)
            return false;
    }

    PlatformKeyboardEvent keyPressEvent = initialKeyEvent;
    keyPressEvent.disambiguateKeyDownEvent(PlatformKeyboardEvent::Char, backwardCompatibilityMode);
    if (keyPressEvent.text().isEmpty())
        return keydownResult;
    RefPtr<KeyboardEvent> keypress = KeyboardEvent::create(keyPressEvent, m_frame->document()->defaultView());
    keypress->setTarget(node);
    if (keydownResult)
        keypress->setDefaultPrevented(true);
#if PLATFORM(MAC)
    keypress->keypressCommands() = keydown->keypressCommands();
#endif
    node->dispatchEvent(keypress, ec);

    return keydownResult || keypress->defaultPrevented() || keypress->defaultHandled();
}

void EventHandler::handleKeyboardSelectionMovement(KeyboardEvent* event)
{
    if (!event)
        return;

    const String& key = event->keyIdentifier();
    bool isShifted = event->getModifierState("Shift");
    bool isOptioned = event->getModifierState("Alt");
    bool isCommanded = event->getModifierState("Meta");

    if (key == "Up") {
        m_frame->selection()->modify((isShifted) ? SelectionController::AlterationExtend : SelectionController::AlterationMove, DirectionBackward, (isCommanded) ? DocumentBoundary : LineGranularity, true);
        event->setDefaultHandled();
    } else if (key == "Down") {
        m_frame->selection()->modify((isShifted) ? SelectionController::AlterationExtend : SelectionController::AlterationMove, DirectionForward, (isCommanded) ? DocumentBoundary : LineGranularity, true);
        event->setDefaultHandled();
    } else if (key == "Left") {
        m_frame->selection()->modify((isShifted) ? SelectionController::AlterationExtend : SelectionController::AlterationMove, DirectionLeft, (isCommanded) ? LineBoundary : (isOptioned) ? WordGranularity : CharacterGranularity, true);
        event->setDefaultHandled();
    } else if (key == "Right") {
        m_frame->selection()->modify((isShifted) ? SelectionController::AlterationExtend : SelectionController::AlterationMove, DirectionRight, (isCommanded) ? LineBoundary : (isOptioned) ? WordGranularity : CharacterGranularity, true);
        event->setDefaultHandled();
    }
}

void EventHandler::defaultKeyboardEventHandler(KeyboardEvent* event)
{
    if (event->type() == eventNames().keydownEvent) {
        m_frame->editor()->handleKeyboardEvent(event);
        if (event->defaultHandled())
            return;
        if (event->keyIdentifier() == "U+0009")
            defaultTabEventHandler(event);
        else {
            FocusDirection direction = focusDirectionForKey(event->keyIdentifier());
            if (direction != FocusDirectionNone)
                defaultArrowEventHandler(direction, event);
        }

        // provides KB navigation and selection for enhanced accessibility users
        if (AXObjectCache::accessibilityEnhancedUserInterfaceEnabled())
            handleKeyboardSelectionMovement(event);
    }
    if (event->type() == eventNames().keypressEvent) {
        m_frame->editor()->handleKeyboardEvent(event);
        if (event->defaultHandled())
            return;
        if (event->charCode() == ' ')
            defaultSpaceEventHandler(event);
    }
}

FocusDirection EventHandler::focusDirectionForKey(const AtomicString& keyIdentifier) const
{
    DEFINE_STATIC_LOCAL(AtomicString, Down, ("Down"));
    DEFINE_STATIC_LOCAL(AtomicString, Up, ("Up"));
    DEFINE_STATIC_LOCAL(AtomicString, Left, ("Left"));
    DEFINE_STATIC_LOCAL(AtomicString, Right, ("Right"));

    FocusDirection retVal = FocusDirectionNone;

    if (keyIdentifier == Down)
        retVal = FocusDirectionDown;
    else if (keyIdentifier == Up)
        retVal = FocusDirectionUp;
    else if (keyIdentifier == Left)
        retVal = FocusDirectionLeft;
    else if (keyIdentifier == Right)
        retVal = FocusDirectionRight;

    return retVal;
}

#if ENABLE(DRAG_SUPPORT)
bool EventHandler::dragHysteresisExceeded(const FloatPoint& floatDragViewportLocation) const
{
    IntPoint dragViewportLocation((int)floatDragViewportLocation.x(), (int)floatDragViewportLocation.y());
    return dragHysteresisExceeded(dragViewportLocation);
}

bool EventHandler::dragHysteresisExceeded(const IntPoint& dragViewportLocation) const
{
    FrameView* view = m_frame->view();
    if (!view)
        return false;
    IntPoint dragLocation = view->windowToContents(dragViewportLocation);
    IntSize delta = dragLocation - m_mouseDownPos;

    int threshold = GeneralDragHysteresis;
    if (dragState().m_dragSrcIsImage)
        threshold = ImageDragHysteresis;
    else if (dragState().m_dragSrcIsLink)
        threshold = LinkDragHysteresis;
    else if (dragState().m_dragSrcInSelection)
        threshold = TextDragHysteresis;

    return abs(delta.width()) >= threshold || abs(delta.height()) >= threshold;
}

void EventHandler::freeClipboard()
{
    if (dragState().m_dragClipboard)
        dragState().m_dragClipboard->setAccessPolicy(ClipboardNumb);
}

bool EventHandler::shouldDragAutoNode(Node* node, const IntPoint& point) const
{
    if (!node || !m_frame->view())
        return false;
    Page* page = m_frame->page();
    return page && page->dragController()->mayStartDragAtEventLocation(m_frame, point, node);
}

void EventHandler::dragSourceEndedAt(const PlatformMouseEvent& event, DragOperation operation)
{
    if (dragState().m_dragSrc && dragState().m_dragSrcMayBeDHTML) {
        dragState().m_dragClipboard->setDestinationOperation(operation);
        // for now we don't care if event handler cancels default behavior, since there is none
        dispatchDragSrcEvent(eventNames().dragendEvent, event);
    }
    freeClipboard();
    dragState().m_dragSrc = 0;
    // In case the drag was ended due to an escape key press we need to ensure
    // that consecutive mousemove events don't reinitiate the drag and drop.
    m_mouseDownMayStartDrag = false;
}

// returns if we should continue "default processing", i.e., whether eventhandler canceled
bool EventHandler::dispatchDragSrcEvent(const AtomicString& eventType, const PlatformMouseEvent& event)
{
    return !dispatchDragEvent(eventType, dragState().m_dragSrc.get(), event, dragState().m_dragClipboard.get());
}

bool EventHandler::handleDrag(const MouseEventWithHitTestResults& event)
{
    if (event.event().button() != LeftButton || event.event().eventType() != MouseEventMoved) {
        // If we allowed the other side of the bridge to handle a drag
        // last time, then m_mousePressed might still be set. So we
        // clear it now to make sure the next move after a drag
        // doesn't look like a drag.
        m_mousePressed = false;
        return false;
    }

    if (eventLoopHandleMouseDragged(event))
        return true;

    // Careful that the drag starting logic stays in sync with eventMayStartDrag()

    if (m_mouseDownMayStartDrag && !dragState().m_dragSrc) {
        allowDHTMLDrag(dragState().m_dragSrcMayBeDHTML, dragState().m_dragSrcMayBeUA);
        if (!dragState().m_dragSrcMayBeDHTML && !dragState().m_dragSrcMayBeUA)
            m_mouseDownMayStartDrag = false; // no element is draggable
    }

    if (m_mouseDownMayStartDrag && !dragState().m_dragSrc) {
        // try to find an element that wants to be dragged
        HitTestRequest request(HitTestRequest::ReadOnly);
        HitTestResult result(m_mouseDownPos);
        m_frame->contentRenderer()->layer()->hitTest(request, result);
        Node* node = result.innerNode();
        if (node && node->renderer())
            dragState().m_dragSrc = node->renderer()->draggableNode(dragState().m_dragSrcMayBeDHTML, dragState().m_dragSrcMayBeUA,
                                                                    m_mouseDownPos.x(), m_mouseDownPos.y(), dragState().m_dragSrcIsDHTML);
        else
            dragState().m_dragSrc = 0;

        if (!dragState().m_dragSrc)
            m_mouseDownMayStartDrag = false; // no element is draggable
        else {
            // remember some facts about this source, while we have a HitTestResult handy
            node = result.URLElement();
            dragState().m_dragSrcIsLink = node && node->isLink();

            node = result.innerNonSharedNode();
            dragState().m_dragSrcIsImage = node && node->renderer() && node->renderer()->isImage();

            dragState().m_dragSrcInSelection = m_frame->selection()->contains(m_mouseDownPos);
        }
    }

    // For drags starting in the selection, the user must wait between the mousedown and mousedrag,
    // or else we bail on the dragging stuff and allow selection to occur
    if (m_mouseDownMayStartDrag && !dragState().m_dragSrcIsImage && dragState().m_dragSrcInSelection && event.event().timestamp() - m_mouseDownTimestamp < TextDragDelay) {
        m_mouseDownMayStartDrag = false;
        dragState().m_dragSrc = 0;
        // ...but if this was the first click in the window, we don't even want to start selection
        if (eventActivatedView(event.event()))
            m_mouseDownMayStartSelect = false;
    }

    if (!m_mouseDownMayStartDrag)
        return !mouseDownMayStartSelect() && !m_mouseDownMayStartAutoscroll;

    // We are starting a text/image/url drag, so the cursor should be an arrow
    if (FrameView* view = m_frame->view()) {
        // FIXME <rdar://7577595>: Custom cursors aren't supported during drag and drop (default to pointer).
        view->setCursor(pointerCursor());
    }

    if (!dragHysteresisExceeded(event.event().pos()))
        return true;

    // Once we're past the hysteresis point, we don't want to treat this gesture as a click
    invalidateClick();

    DragOperation srcOp = DragOperationNone;

    freeClipboard(); // would only happen if we missed a dragEnd.  Do it anyway, just
                     // to make sure it gets numbified
    dragState().m_dragClipboard = createDraggingClipboard();

    if (dragState().m_dragSrcMayBeDHTML) {
        // Check to see if the is a DOM based drag, if it is get the DOM specified drag
        // image and offset
        if (dragState().m_dragSrcIsDHTML) {
            if (RenderObject* renderer = dragState().m_dragSrc->renderer()) {
                // FIXME: This doesn't work correctly with transforms.
                FloatPoint absPos = renderer->localToAbsolute();
                IntSize delta = m_mouseDownPos - roundedIntPoint(absPos);
                dragState().m_dragClipboard->setDragImageElement(dragState().m_dragSrc.get(), toPoint(delta));
            } else {
                // The renderer has disappeared, this can happen if the onStartDrag handler has hidden
                // the element in some way.  In this case we just kill the drag.
                m_mouseDownMayStartDrag = false;
                goto cleanupDrag;
            }
        }

        m_mouseDownMayStartDrag = dispatchDragSrcEvent(eventNames().dragstartEvent, m_mouseDown)
            && !m_frame->selection()->isInPasswordField();

        // Invalidate clipboard here against anymore pasteboard writing for security.  The drag
        // image can still be changed as we drag, but not the pasteboard data.
        dragState().m_dragClipboard->setAccessPolicy(ClipboardImageWritable);

        if (m_mouseDownMayStartDrag) {
            // gather values from DHTML element, if it set any
            srcOp = dragState().m_dragClipboard->sourceOperation();

            // Yuck, a draggedImage:moveTo: message can be fired as a result of kicking off the
            // drag with dragImage!  Because of that dumb reentrancy, we may think we've not
            // started the drag when that happens.  So we have to assume it's started before we
            // kick it off.
            dragState().m_dragClipboard->setDragHasStarted();
        }
    }

    if (m_mouseDownMayStartDrag) {
        Page* page = m_frame->page();
        DragController* dragController = page ? page->dragController() : 0;
        bool startedDrag = dragController && dragController->startDrag(m_frame, dragState().m_dragClipboard.get(), srcOp, event.event(), m_mouseDownPos, dragState().m_dragSrcIsDHTML);
        if (!startedDrag && dragState().m_dragSrcMayBeDHTML) {
            // Drag was canned at the last minute - we owe m_dragSrc a DRAGEND event
            dispatchDragSrcEvent(eventNames().dragendEvent, event.event());
            m_mouseDownMayStartDrag = false;
        }
    }

cleanupDrag:
    if (!m_mouseDownMayStartDrag) {
        // something failed to start the drag, cleanup
        freeClipboard();
        dragState().m_dragSrc = 0;
    }

    // No more default handling (like selection), whether we're past the hysteresis bounds or not
    return true;
}
#endif // ENABLE(DRAG_SUPPORT)

bool EventHandler::handleTextInputEvent(const String& text, Event* underlyingEvent, TextEventInputType inputType)
{
    // Platforms should differentiate real commands like selectAll from text input in disguise (like insertNewline),
    // and avoid dispatching text input events from keydown default handlers.
    ASSERT(!underlyingEvent || !underlyingEvent->isKeyboardEvent() || static_cast<KeyboardEvent*>(underlyingEvent)->type() == eventNames().keypressEvent);

    if (!m_frame)
        return false;

    EventTarget* target;
    if (underlyingEvent)
        target = underlyingEvent->target();
    else
        target = eventTargetNodeForDocument(m_frame->document());
    if (!target)
        return false;

    if (FrameView* view = m_frame->view())
        view->resetDeferredRepaintDelay();

    RefPtr<TextEvent> event = TextEvent::create(m_frame->domWindow(), text, inputType);
    event->setUnderlyingEvent(underlyingEvent);

    ExceptionCode ec;
    target->dispatchEvent(event, ec);
    return event->defaultHandled();
}

bool EventHandler::isKeyboardOptionTab(KeyboardEvent* event)
{
    return event
        && (event->type() == eventNames().keydownEvent || event->type() == eventNames().keypressEvent)
        && event->altKey()
        && event->keyIdentifier() == "U+0009";
}

static bool eventInvertsTabsToLinksClientCallResult(KeyboardEvent* event)
{
#if PLATFORM(MAC) || PLATFORM(QT) || PLATFORM(HAIKU) || PLATFORM(EFL)
    return EventHandler::isKeyboardOptionTab(event);
#else
    return false;
#endif
}

bool EventHandler::tabsToLinks(KeyboardEvent* event) const
{
    // FIXME: This function needs a better name. It can be called for keypresses other than Tab when spatial navigation is enabled.

    Page* page = m_frame->page();
    if (!page)
        return false;

    bool tabsToLinksClientCallResult = page->chrome()->client()->keyboardUIMode() & KeyboardAccessTabsToLinks;
    return eventInvertsTabsToLinksClientCallResult(event) ? !tabsToLinksClientCallResult : tabsToLinksClientCallResult;
}

void EventHandler::defaultTextInputEventHandler(TextEvent* event)
{
    if (m_frame->editor()->handleTextEvent(event))
        event->setDefaultHandled();
}

#if PLATFORM(QT) || PLATFORM(MAC) || PLATFORM(ANDROID)

// These two platforms handle the space event in the platform-specific WebKit code.
// Eventually it would be good to eliminate that and use the code here instead, but
// the Qt version is inside an ifdef and the Mac version has some extra behavior
// so we can't unify everything yet.
void EventHandler::defaultSpaceEventHandler(KeyboardEvent*)
{
}

#else

void EventHandler::defaultSpaceEventHandler(KeyboardEvent* event)
{
    ScrollLogicalDirection direction = event->shiftKey() ? ScrollBlockDirectionBackward : ScrollBlockDirectionForward;
    if (logicalScrollOverflow(direction, ScrollByPage)) {
        event->setDefaultHandled();
        return;
    }

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

    if (view->logicalScroll(direction, ScrollByPage))
        event->setDefaultHandled();
}

#endif

void EventHandler::defaultArrowEventHandler(FocusDirection focusDirection, KeyboardEvent* event)
{
    if (event->ctrlKey() || event->metaKey() || event->altGraphKey() || event->shiftKey())
        return;

    Page* page = m_frame->page();
    if (!page)
        return;

    if (!isSpatialNavigationEnabled(m_frame))
        return;

    // Arrows and other possible directional navigation keys can be used in design
    // mode editing.
    if (m_frame->document()->inDesignMode())
        return;

    if (page->focusController()->advanceFocus(focusDirection, event))
        event->setDefaultHandled();
}

void EventHandler::defaultTabEventHandler(KeyboardEvent* event)
{
    // We should only advance focus on tabs if no special modifier keys are held down.
    if (event->ctrlKey() || event->metaKey() || event->altGraphKey())
        return;

    Page* page = m_frame->page();
    if (!page)
        return;
    if (!page->tabKeyCyclesThroughElements())
        return;

    FocusDirection focusDirection = event->shiftKey() ? FocusDirectionBackward : FocusDirectionForward;

    // Tabs can be used in design mode editing.
    if (m_frame->document()->inDesignMode())
        return;

    if (page->focusController()->advanceFocus(focusDirection, event))
        event->setDefaultHandled();
}

void EventHandler::capsLockStateMayHaveChanged()
{
    Document* d = m_frame->document();
    if (Node* node = d->focusedNode()) {
        if (RenderObject* r = node->renderer()) {
            if (r->isTextField())
                toRenderTextControlSingleLine(r)->capsLockStateMayHaveChanged();
        }
    }
}

void EventHandler::sendResizeEvent()
{
    m_frame->document()->enqueueWindowEvent(Event::create(eventNames().resizeEvent, false, false));
}

void EventHandler::sendScrollEvent()
{
    setFrameWasScrolledByUser();
    if (m_frame->view() && m_frame->document())
        m_frame->document()->eventQueue()->enqueueScrollEvent(m_frame->document(), EventQueue::ScrollEventDocumentTarget);
}

void EventHandler::setFrameWasScrolledByUser()
{
    FrameView* v = m_frame->view();
    if (v)
        v->setWasScrolledByUser(true);
}

bool EventHandler::passMousePressEventToScrollbar(MouseEventWithHitTestResults& mev, Scrollbar* scrollbar)
{
    if (!scrollbar || !scrollbar->enabled())
        return false;
    setFrameWasScrolledByUser();
    return scrollbar->mouseDown(mev.event());
}

// If scrollbar (under mouse) is different from last, send a mouse exited. Set
// last to scrollbar if setLast is true; else set last to 0.
void EventHandler::updateLastScrollbarUnderMouse(Scrollbar* scrollbar, bool setLast)
{
    if (m_lastScrollbarUnderMouse != scrollbar) {
        // Send mouse exited to the old scrollbar.
        if (m_lastScrollbarUnderMouse)
            m_lastScrollbarUnderMouse->mouseExited();
        m_lastScrollbarUnderMouse = setLast ? scrollbar : 0;
    }
}

#if ENABLE(TOUCH_EVENTS)

static const AtomicString& eventNameForTouchPointState(PlatformTouchPoint::State state)
{
    switch (state) {
    case PlatformTouchPoint::TouchReleased:
        return eventNames().touchendEvent;
    case PlatformTouchPoint::TouchCancelled:
        return eventNames().touchcancelEvent;
    case PlatformTouchPoint::TouchPressed:
        return eventNames().touchstartEvent;
    case PlatformTouchPoint::TouchMoved:
        return eventNames().touchmoveEvent;
    default:
        ASSERT_NOT_REACHED();
        return emptyAtom;
    }
}

bool EventHandler::handleTouchEvent(const PlatformTouchEvent& event)
{
    // First build up the lists to use for the 'touches', 'targetTouches' and 'changedTouches' attributes
    // in the JS event. See http://www.sitepen.com/blog/2008/07/10/touching-and-gesturing-on-the-iphone/
    // for an overview of how these lists fit together.

    // Holds the complete set of touches on the screen and will be used as the 'touches' list in the JS event.
    RefPtr<TouchList> touches = TouchList::create();

    // A different view on the 'touches' list above, filtered and grouped by event target. Used for the
    // 'targetTouches' list in the JS event.
    typedef HashMap<EventTarget*, RefPtr<TouchList> > TargetTouchesMap;
    TargetTouchesMap touchesByTarget;

    // Array of touches per state, used to assemble the 'changedTouches' list in the JS event.
    typedef HashSet<RefPtr<EventTarget> > EventTargetSet;
    struct {
        // The touches corresponding to the particular change state this struct instance represents.
        RefPtr<TouchList> m_touches;
        // Set of targets involved in m_touches.
        EventTargetSet m_targets;
    } changedTouches[PlatformTouchPoint::TouchStateEnd];

    const Vector<PlatformTouchPoint>& points = event.touchPoints();

    UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);

    for (unsigned i = 0; i < points.size(); ++i) {
        const PlatformTouchPoint& point = points[i];
        PlatformTouchPoint::State pointState = point.state();
        IntPoint pagePoint = documentPointForWindowPoint(m_frame, point.pos());

        HitTestRequest::HitTestRequestType hitType = HitTestRequest::Active | HitTestRequest::ReadOnly;
        // The HitTestRequest types used for mouse events map quite adequately
        // to touch events. Note that in addition to meaning that the hit test
        // should affect the active state of the current node if necessary,
        // HitTestRequest::Active signifies that the hit test is taking place
        // with the mouse (or finger in this case) being pressed.
        switch (pointState) {
        case PlatformTouchPoint::TouchPressed:
            hitType = HitTestRequest::Active;
            break;
        case PlatformTouchPoint::TouchMoved:
            hitType = HitTestRequest::Active | HitTestRequest::MouseMove | HitTestRequest::ReadOnly;
            break;
        case PlatformTouchPoint::TouchReleased:
        case PlatformTouchPoint::TouchCancelled:
            hitType = HitTestRequest::MouseUp;
            break;
        default:
            break;
        }
#if PLATFORM(ANDROID)
        Node* node = 0;
        if (m_capturingTouchEventsNode)
            node = m_capturingTouchEventsNode.get();
        else {
            HitTestResult result = hitTestResultAtPoint(pagePoint, /*allowShadowContent*/ false, false, DontHitTestScrollbars, hitType);
            node = result.innerNode();
            ASSERT(node);

            // Touch events should not go to text nodes
            if (node->isTextNode())
                node = node->parentNode();
        }
#else
        HitTestResult result = hitTestResultAtPoint(pagePoint, /*allowShadowContent*/ false, false, DontHitTestScrollbars, hitType);
        Node* node = result.innerNode();
        ASSERT(node);

        // Touch events should not go to text nodes
        if (node->isTextNode())
            node = node->parentNode();
#endif


        Document* doc = node->document();
        if (!doc)
            continue;
        if (!doc->hasListenerType(Document::TOUCH_LISTENER))
            continue;

        if (m_frame != doc->frame()) {
            // pagePoint should always be relative to the target elements containing frame.
            pagePoint = documentPointForWindowPoint(doc->frame(), point.pos());
        }

        int adjustedPageX = lroundf(pagePoint.x() / m_frame->pageZoomFactor());
        int adjustedPageY = lroundf(pagePoint.y() / m_frame->pageZoomFactor());

        // Increment the platform touch id by 1 to avoid storing a key of 0 in the hashmap.
        unsigned touchPointTargetKey = point.id() + 1;
        RefPtr<EventTarget> touchTarget;
#if PLATFORM(ANDROID)
        if (m_capturingTouchEventsNode)
            touchTarget = node;
        else {
#endif
        if (pointState == PlatformTouchPoint::TouchPressed) {
            m_originatingTouchPointTargets.set(touchPointTargetKey, node);
            touchTarget = node;
        } else if (pointState == PlatformTouchPoint::TouchReleased || pointState == PlatformTouchPoint::TouchCancelled) {
            // The target should be the original target for this touch, so get it from the hashmap. As it's a release or cancel
            // we also remove it from the map.
            touchTarget = m_originatingTouchPointTargets.take(touchPointTargetKey);
        } else
            touchTarget = m_originatingTouchPointTargets.get(touchPointTargetKey);
#if PLATFORM(ANDROID)
        }
#endif
        if (!touchTarget.get())
            continue;

        RefPtr<Touch> touch = Touch::create(doc->frame(), touchTarget.get(), point.id(),
                                            point.screenPos().x(), point.screenPos().y(),
                                            adjustedPageX, adjustedPageY);

        // Ensure this target's touch list exists, even if it ends up empty, so it can always be passed to TouchEvent::Create below.
        TargetTouchesMap::iterator targetTouchesIterator = touchesByTarget.find(touchTarget.get());
        if (targetTouchesIterator == touchesByTarget.end())
            targetTouchesIterator = touchesByTarget.set(touchTarget.get(), TouchList::create()).first;

        // touches and targetTouches should only contain information about touches still on the screen, so if this point is
        // released or cancelled it will only appear in the changedTouches list.
        if (pointState != PlatformTouchPoint::TouchReleased && pointState != PlatformTouchPoint::TouchCancelled) {
            touches->append(touch);
            targetTouchesIterator->second->append(touch);
        }

        // Now build up the correct list for changedTouches.
        // Note that  any touches that are in the TouchStationary state (e.g. if
        // the user had several points touched but did not move them all) should
        // never be in the changedTouches list so we do not handle them explicitly here.
        // See https://bugs.webkit.org/show_bug.cgi?id=37609 for further discussion
        // about the TouchStationary state.
        if (pointState != PlatformTouchPoint::TouchStationary) {
            ASSERT(pointState < PlatformTouchPoint::TouchStateEnd);
            if (!changedTouches[pointState].m_touches)
                changedTouches[pointState].m_touches = TouchList::create();
            changedTouches[pointState].m_touches->append(touch);
            changedTouches[pointState].m_targets.add(touchTarget);
        }
    }
    m_touchPressed = touches->length() > 0;

    // Now iterate the changedTouches list and m_targets within it, sending events to the tagets as required.
    bool defaultPrevented = false;
    RefPtr<TouchList> emptyList = TouchList::create();
    for (unsigned state = 0; state != PlatformTouchPoint::TouchStateEnd; ++state) {
        if (!changedTouches[state].m_touches)
            continue;

        // When sending a touch cancel event, use empty touches and targetTouches lists.
        bool isTouchCancelEvent = (state == PlatformTouchPoint::TouchCancelled);
        RefPtr<TouchList>& effectiveTouches(isTouchCancelEvent ? emptyList : touches);
#if PLATFORM(ANDROID)
        AtomicString stateName(eventNameForTouchPointState(static_cast<PlatformTouchPoint::State>(state)));
        if (event.type() == TouchLongPress)
            stateName = eventNames().touchlongpressEvent;
        else if (event.type() == TouchDoubleTap)
            stateName = eventNames().touchdoubletapEvent;
#else
        const AtomicString& stateName(eventNameForTouchPointState(static_cast<PlatformTouchPoint::State>(state)));
#endif
        const EventTargetSet& targetsForState = changedTouches[state].m_targets;

        for (EventTargetSet::const_iterator it = targetsForState.begin(); it != targetsForState.end(); ++it) {
            EventTarget* touchEventTarget = it->get();
            RefPtr<TouchList> targetTouches(isTouchCancelEvent ? emptyList : touchesByTarget.get(touchEventTarget));
            ASSERT(targetTouches);

            RefPtr<TouchEvent> touchEvent =
                TouchEvent::create(effectiveTouches.get(), targetTouches.get(), changedTouches[state].m_touches.get(),
                                   stateName, touchEventTarget->toNode()->document()->defaultView(),
                                   0, 0, 0, 0, event.ctrlKey(), event.altKey(), event.shiftKey(), event.metaKey());
            ExceptionCode ec = 0;
            touchEventTarget->dispatchEvent(touchEvent.get(), ec);
            defaultPrevented |= touchEvent->defaultPrevented();
        }
    }

#if ENABLE(GESTURE_RECOGNIZER)
    if (m_gestureRecognizer)
        m_gestureRecognizer->processTouchEventForGesture(event, this, defaultPrevented);
#endif

    return defaultPrevented;
}
#endif

}