Source/WebCore/page/scrolling/ScrollingCoordinator.cpp

/*
 * Copyright (C) 2011 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``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 INC. OR ITS 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 "ScrollingCoordinator.h"

#include "Document.h"
#include "Frame.h"
#include "FrameView.h"
#include "GraphicsLayer.h"
#include "IntRect.h"
#include "Page.h"
#include "PlatformWheelEvent.h"
#include "PluginViewBase.h"
#include "Region.h"
#include "RenderView.h"
#include "ScrollAnimator.h"
#include <wtf/MainThread.h>
#include <wtf/text/StringBuilder.h>

#if USE(ACCELERATED_COMPOSITING)
#include "RenderLayerCompositor.h"
#endif

#if ENABLE(THREADED_SCROLLING)
#include "ScrollingCoordinatorMac.h"
#endif

#if USE(COORDINATED_GRAPHICS)
#include "ScrollingCoordinatorCoordinatedGraphics.h"
#endif

#if PLATFORM(BLACKBERRY)
#include "ScrollingCoordinatorBlackBerry.h"
#endif

namespace WebCore {

PassRefPtr<ScrollingCoordinator> ScrollingCoordinator::create(Page* page)
{
#if USE(ACCELERATED_COMPOSITING) && ENABLE(THREADED_SCROLLING)
    return adoptRef(new ScrollingCoordinatorMac(page));
#endif

#if USE(COORDINATED_GRAPHICS)
    return adoptRef(new ScrollingCoordinatorCoordinatedGraphics(page));
#endif

#if PLATFORM(BLACKBERRY)
    return adoptRef(new ScrollingCoordinatorBlackBerry(page));
#endif

    return adoptRef(new ScrollingCoordinator(page));
}

ScrollingCoordinator::ScrollingCoordinator(Page* page)
    : m_page(page)
    , m_updateMainFrameScrollPositionTimer(this, &ScrollingCoordinator::updateMainFrameScrollPositionTimerFired)
    , m_scheduledUpdateIsProgrammaticScroll(false)
    , m_scheduledScrollingLayerPositionAction(SyncScrollingLayerPosition)
    , m_forceMainThreadScrollLayerPositionUpdates(false)
{
}

ScrollingCoordinator::~ScrollingCoordinator()
{
    ASSERT(!m_page);
}

void ScrollingCoordinator::pageDestroyed()
{
    ASSERT(m_page);
    m_page = 0;
}

bool ScrollingCoordinator::coordinatesScrollingForFrameView(FrameView* frameView) const
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    // We currently only handle the main frame.
    if (frameView->frame() != m_page->mainFrame())
        return false;

    // We currently only support composited mode.
#if USE(ACCELERATED_COMPOSITING)
    RenderView* renderView = m_page->mainFrame()->contentRenderer();
    if (!renderView)
        return false;
    return renderView->usesCompositing();
#else
    return false;
#endif
}

Region ScrollingCoordinator::computeNonFastScrollableRegion(const Frame* frame, const IntPoint& frameLocation) const
{
    Region nonFastScrollableRegion;
    FrameView* frameView = frame->view();
    if (!frameView)
        return nonFastScrollableRegion;

    IntPoint offset = frameLocation;
    offset.moveBy(frameView->frameRect().location());

    if (const FrameView::ScrollableAreaSet* scrollableAreas = frameView->scrollableAreas()) {
        for (FrameView::ScrollableAreaSet::const_iterator it = scrollableAreas->begin(), end = scrollableAreas->end(); it != end; ++it) {
            ScrollableArea* scrollableArea = *it;
#if USE(ACCELERATED_COMPOSITING)
            // Composited scrollable areas can be scrolled off the main thread.
            if (scrollableArea->usesCompositedScrolling())
                continue;
#endif
            IntRect box = scrollableArea->scrollableAreaBoundingBox();
            box.moveBy(offset);
            nonFastScrollableRegion.unite(box);
        }
    }

    if (const HashSet<RefPtr<Widget> >* children = frameView->children()) {
        for (HashSet<RefPtr<Widget> >::const_iterator it = children->begin(), end = children->end(); it != end; ++it) {
            if (!(*it)->isPluginViewBase())
                continue;

            PluginViewBase* pluginViewBase = toPluginViewBase((*it).get());
            if (pluginViewBase->wantsWheelEvents())
                nonFastScrollableRegion.unite(pluginViewBase->frameRect());
        }
    }

    FrameTree* tree = frame->tree();
    for (Frame* subFrame = tree->firstChild(); subFrame; subFrame = subFrame->tree()->nextSibling())
        nonFastScrollableRegion.unite(computeNonFastScrollableRegion(subFrame, offset));

    return nonFastScrollableRegion;
}

#if ENABLE(TOUCH_EVENT_TRACKING)
static void accumulateRendererTouchEventTargetRects(Vector<IntRect>& rects, const RenderObject* renderer, const IntRect& parentRect = IntRect())
{
    IntRect adjustedParentRect = parentRect;
    if (parentRect.isEmpty() || renderer->isFloating() || renderer->isPositioned() || renderer->hasTransform()) {
        // FIXME: This method is O(N^2) as it walks the tree to the root for every renderer. RenderGeometryMap would fix this.
        IntRect r = enclosingIntRect(renderer->clippedOverflowRectForRepaint(0));
        if (!r.isEmpty()) {
            // Convert to the top-level view's coordinates.
            ASSERT(renderer->document()->view());
            r = renderer->document()->view()->convertToRootView(r);

            if (!parentRect.contains(r)) {
                rects.append(r);
                adjustedParentRect = r;
            }
        }
    }

    for (RenderObject* child = renderer->firstChild(); child; child = child->nextSibling())
        accumulateRendererTouchEventTargetRects(rects, child, adjustedParentRect);
}

static void accumulateDocumentEventTargetRects(Vector<IntRect>& rects, const Document* document)
{
    ASSERT(document);
    if (!document->touchEventTargets())
        return;

    const TouchEventTargetSet* targets = document->touchEventTargets();
    for (TouchEventTargetSet::const_iterator iter = targets->begin(); iter != targets->end(); ++iter) {
        const Node* touchTarget = iter->key;
        if (!touchTarget->inDocument())
            continue;

        if (touchTarget == document) {
            if (RenderView* view = document->renderView()) {
                IntRect r;
                if (touchTarget == document->topDocument())
                    r = view->documentRect();
                else
                    r = enclosingIntRect(view->clippedOverflowRectForRepaint(0));

                if (!r.isEmpty()) {
                    ASSERT(view->document()->view());
                    r = view->document()->view()->convertToRootView(r);
                    rects.append(r);
                }
            }
            return;
        }

        if (touchTarget->isDocumentNode() && touchTarget != document) {
            accumulateDocumentEventTargetRects(rects, toDocument(touchTarget));
            continue;
        }

        if (RenderObject* renderer = touchTarget->renderer())
            accumulateRendererTouchEventTargetRects(rects, renderer);
    }
}

void ScrollingCoordinator::computeAbsoluteTouchEventTargetRects(const Document* document, Vector<IntRect>& rects)
{
    ASSERT(document);
    if (!document->view())
        return;

    // FIXME: These rects won't be properly updated if the renderers are in a sub-tree that scrolls.
    accumulateDocumentEventTargetRects(rects, document);
}
#endif

unsigned ScrollingCoordinator::computeCurrentWheelEventHandlerCount()
{
    unsigned wheelEventHandlerCount = 0;

    for (Frame* frame = m_page->mainFrame(); frame; frame = frame->tree()->traverseNext()) {
        if (frame->document())
            wheelEventHandlerCount += frame->document()->wheelEventHandlerCount();
    }

    return wheelEventHandlerCount;
}

void ScrollingCoordinator::frameViewWheelEventHandlerCountChanged(FrameView* frameView)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    recomputeWheelEventHandlerCountForFrameView(frameView);
}

void ScrollingCoordinator::frameViewHasSlowRepaintObjectsDidChange(FrameView* frameView)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    if (!coordinatesScrollingForFrameView(frameView))
        return;

    updateShouldUpdateScrollLayerPositionOnMainThread();
}

void ScrollingCoordinator::frameViewFixedObjectsDidChange(FrameView* frameView)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    if (!coordinatesScrollingForFrameView(frameView))
        return;

    updateShouldUpdateScrollLayerPositionOnMainThread();
}

#if USE(ACCELERATED_COMPOSITING)
GraphicsLayer* ScrollingCoordinator::scrollLayerForScrollableArea(ScrollableArea* scrollableArea)
{
    return scrollableArea->layerForScrolling();
}

GraphicsLayer* ScrollingCoordinator::horizontalScrollbarLayerForScrollableArea(ScrollableArea* scrollableArea)
{
    return scrollableArea->layerForHorizontalScrollbar();
}

GraphicsLayer* ScrollingCoordinator::verticalScrollbarLayerForScrollableArea(ScrollableArea* scrollableArea)
{
    return scrollableArea->layerForVerticalScrollbar();
}
#endif

GraphicsLayer* ScrollingCoordinator::scrollLayerForFrameView(FrameView* frameView)
{
#if USE(ACCELERATED_COMPOSITING)
    Frame* frame = frameView->frame();
    if (!frame)
        return 0;

    RenderView* renderView = frame->contentRenderer();
    if (!renderView)
        return 0;
    return renderView->compositor()->scrollLayer();
#else
    UNUSED_PARAM(frameView);
    return 0;
#endif
}

GraphicsLayer* ScrollingCoordinator::headerLayerForFrameView(FrameView* frameView)
{
#if USE(ACCELERATED_COMPOSITING) && ENABLE(RUBBER_BANDING)
    Frame* frame = frameView->frame();
    if (!frame)
        return 0;

    RenderView* renderView = frame->contentRenderer();
    if (!renderView)
        return 0;

    return renderView->compositor()->headerLayer();
#else
    UNUSED_PARAM(frameView);
    return 0;
#endif
}

GraphicsLayer* ScrollingCoordinator::footerLayerForFrameView(FrameView* frameView)
{
#if USE(ACCELERATED_COMPOSITING) && ENABLE(RUBBER_BANDING)
    Frame* frame = frameView->frame();
    if (!frame)
        return 0;

    RenderView* renderView = frame->contentRenderer();
    if (!renderView)
        return 0;
    return renderView->compositor()->footerLayer();
#else
    UNUSED_PARAM(frameView);
    return 0;
#endif
}

GraphicsLayer* ScrollingCoordinator::counterScrollingLayerForFrameView(FrameView* frameView)
{
#if USE(ACCELERATED_COMPOSITING)
    Frame* frame = frameView->frame();
    if (!frame)
        return 0;

    RenderView* renderView = frame->contentRenderer();
    if (!renderView)
        return 0;
    return renderView->compositor()->fixedRootBackgroundLayer();
#else
    UNUSED_PARAM(frameView);
    return 0;
#endif
}

void ScrollingCoordinator::frameViewRootLayerDidChange(FrameView* frameView)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    if (!coordinatesScrollingForFrameView(frameView))
        return;

    frameViewLayoutUpdated(frameView);
    recomputeWheelEventHandlerCountForFrameView(frameView);
    updateShouldUpdateScrollLayerPositionOnMainThread();
}

void ScrollingCoordinator::scheduleUpdateMainFrameScrollPosition(const IntPoint& scrollPosition, bool programmaticScroll, SetOrSyncScrollingLayerPosition scrollingLayerPositionAction)
{
    if (m_updateMainFrameScrollPositionTimer.isActive()) {
        if (m_scheduledUpdateIsProgrammaticScroll == programmaticScroll
            && m_scheduledScrollingLayerPositionAction == scrollingLayerPositionAction) {
            m_scheduledUpdateScrollPosition = scrollPosition;
            return;
        }
    
        // If the parameters don't match what was previosly scheduled, dispatch immediately.
        m_updateMainFrameScrollPositionTimer.stop();
        updateMainFrameScrollPosition(m_scheduledUpdateScrollPosition, m_scheduledUpdateIsProgrammaticScroll, m_scheduledScrollingLayerPositionAction);
        updateMainFrameScrollPosition(scrollPosition, programmaticScroll, scrollingLayerPositionAction);
        return;
    }

    m_scheduledUpdateScrollPosition = scrollPosition;
    m_scheduledUpdateIsProgrammaticScroll = programmaticScroll;
    m_scheduledScrollingLayerPositionAction = scrollingLayerPositionAction;
    m_updateMainFrameScrollPositionTimer.startOneShot(0);
}

void ScrollingCoordinator::updateMainFrameScrollPositionTimerFired(Timer<ScrollingCoordinator>*)
{
    updateMainFrameScrollPosition(m_scheduledUpdateScrollPosition, m_scheduledUpdateIsProgrammaticScroll, m_scheduledScrollingLayerPositionAction);
}

void ScrollingCoordinator::updateMainFrameScrollPosition(const IntPoint& scrollPosition, bool programmaticScroll, SetOrSyncScrollingLayerPosition scrollingLayerPositionAction)
{
    ASSERT(isMainThread());

    if (!m_page)
        return;

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

    bool oldProgrammaticScroll = frameView->inProgrammaticScroll();
    frameView->setInProgrammaticScroll(programmaticScroll);

    frameView->setConstrainsScrollingToContentEdge(false);
    frameView->notifyScrollPositionChanged(scrollPosition);
    frameView->setConstrainsScrollingToContentEdge(true);

    frameView->setInProgrammaticScroll(oldProgrammaticScroll);

#if USE(ACCELERATED_COMPOSITING)
    if (GraphicsLayer* scrollLayer = scrollLayerForFrameView(frameView)) {
        GraphicsLayer* counterScrollingLayer = counterScrollingLayerForFrameView(frameView);
        GraphicsLayer* headerLayer = headerLayerForFrameView(frameView);
        GraphicsLayer* footerLayer = footerLayerForFrameView(frameView);
        IntSize scrollOffsetForFixed = frameView->scrollOffsetForFixedPosition();

        if (programmaticScroll || scrollingLayerPositionAction == SetScrollingLayerPosition) {
            scrollLayer->setPosition(-frameView->scrollPosition());
            if (counterScrollingLayer)
                counterScrollingLayer->setPosition(IntPoint(scrollOffsetForFixed));
            if (headerLayer)
                headerLayer->setPosition(FloatPoint(scrollOffsetForFixed.width(), 0));
            if (footerLayer)
                footerLayer->setPosition(FloatPoint(scrollOffsetForFixed.width(), frameView->totalContentsSize().height() - frameView->footerHeight()));
        } else {
            scrollLayer->syncPosition(-frameView->scrollPosition());
            if (counterScrollingLayer)
                counterScrollingLayer->syncPosition(IntPoint(scrollOffsetForFixed));
            if (headerLayer)
                headerLayer->syncPosition(FloatPoint(scrollOffsetForFixed.width(), 0));
            if (footerLayer)
                footerLayer->syncPosition(FloatPoint(scrollOffsetForFixed.width(), frameView->totalContentsSize().height() - frameView->footerHeight()));

            LayoutRect viewportRect = frameView->viewportConstrainedVisibleContentRect();
            syncChildPositions(viewportRect);
        }
    }
#else
    UNUSED_PARAM(scrollingLayerPositionAction);
#endif
}

#if PLATFORM(MAC)
void ScrollingCoordinator::handleWheelEventPhase(PlatformWheelEventPhase phase)
{
    ASSERT(isMainThread());

    if (!m_page)
        return;

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

    frameView->scrollAnimator()->handleWheelEventPhase(phase);
}
#endif

bool ScrollingCoordinator::hasVisibleSlowRepaintViewportConstrainedObjects(FrameView* frameView) const
{
    const FrameView::ViewportConstrainedObjectSet* viewportConstrainedObjects = frameView->viewportConstrainedObjects();
    if (!viewportConstrainedObjects)
        return false;

#if USE(ACCELERATED_COMPOSITING)
    for (FrameView::ViewportConstrainedObjectSet::const_iterator it = viewportConstrainedObjects->begin(), end = viewportConstrainedObjects->end(); it != end; ++it) {
        RenderObject* viewportConstrainedObject = *it;
        if (!viewportConstrainedObject->isBoxModelObject() || !viewportConstrainedObject->hasLayer())
            return true;
        RenderLayer* layer = toRenderBoxModelObject(viewportConstrainedObject)->layer();
        // Any explicit reason that a fixed position element is not composited shouldn't cause slow scrolling.
        if (!layer->isComposited() && layer->viewportConstrainedNotCompositedReason() == RenderLayer::NoNotCompositedReason)
            return true;
    }
    return false;
#else
    return viewportConstrainedObjects->size();
#endif
}

MainThreadScrollingReasons ScrollingCoordinator::mainThreadScrollingReasons() const
{
    FrameView* frameView = m_page->mainFrame()->view();
    if (!frameView)
        return static_cast<MainThreadScrollingReasons>(0);

    MainThreadScrollingReasons mainThreadScrollingReasons = (MainThreadScrollingReasons)0;

    if (m_forceMainThreadScrollLayerPositionUpdates)
        mainThreadScrollingReasons |= ForcedOnMainThread;
    if (frameView->hasSlowRepaintObjects())
        mainThreadScrollingReasons |= HasSlowRepaintObjects;
    if (!supportsFixedPositionLayers() && frameView->hasViewportConstrainedObjects())
        mainThreadScrollingReasons |= HasViewportConstrainedObjectsWithoutSupportingFixedLayers;
    if (supportsFixedPositionLayers() && hasVisibleSlowRepaintViewportConstrainedObjects(frameView))
        mainThreadScrollingReasons |= HasNonLayerViewportConstrainedObjects;
    if (m_page->mainFrame()->document() && m_page->mainFrame()->document()->isImageDocument())
        mainThreadScrollingReasons |= IsImageDocument;

    return mainThreadScrollingReasons;
}

void ScrollingCoordinator::updateShouldUpdateScrollLayerPositionOnMainThread()
{
    setShouldUpdateScrollLayerPositionOnMainThread(mainThreadScrollingReasons());
}

void ScrollingCoordinator::setForceMainThreadScrollLayerPositionUpdates(bool forceMainThreadScrollLayerPositionUpdates)
{
    if (m_forceMainThreadScrollLayerPositionUpdates == forceMainThreadScrollLayerPositionUpdates)
        return;

    m_forceMainThreadScrollLayerPositionUpdates = forceMainThreadScrollLayerPositionUpdates;
    updateShouldUpdateScrollLayerPositionOnMainThread();
}

ScrollingNodeID ScrollingCoordinator::uniqueScrollLayerID()
{
    static ScrollingNodeID uniqueScrollLayerID = 1;
    return uniqueScrollLayerID++;
}

String ScrollingCoordinator::scrollingStateTreeAsText() const
{
    return String();
}

String ScrollingCoordinator::mainThreadScrollingReasonsAsText(MainThreadScrollingReasons reasons)
{
    StringBuilder stringBuilder;

    if (reasons & ScrollingCoordinator::ForcedOnMainThread)
        stringBuilder.append("Forced on main thread, ");
    if (reasons & ScrollingCoordinator::HasSlowRepaintObjects)
        stringBuilder.append("Has slow repaint objects, ");
    if (reasons & ScrollingCoordinator::HasViewportConstrainedObjectsWithoutSupportingFixedLayers)
        stringBuilder.append("Has viewport constrained objects without supporting fixed layers, ");
    if (reasons & ScrollingCoordinator::HasNonLayerViewportConstrainedObjects)
        stringBuilder.append("Has non-layer viewport-constrained objects, ");
    if (reasons & ScrollingCoordinator::IsImageDocument)
        stringBuilder.append("Is image document, ");

    if (stringBuilder.length())
        stringBuilder.resize(stringBuilder.length() - 2);
    return stringBuilder.toString();
}

String ScrollingCoordinator::mainThreadScrollingReasonsAsText() const
{
    return mainThreadScrollingReasonsAsText(mainThreadScrollingReasons());
}

} // namespace WebCore