Source/WebCore/page/scrolling/AsyncScrollingCoordinator.cpp

/*
 * Copyright (C) 2014 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)
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 */

#include "config.h"

#if ENABLE(ASYNC_SCROLLING)
#include "AsyncScrollingCoordinator.h"

#include "Frame.h"
#include "FrameView.h"
#include "GraphicsLayer.h"
#include "MainFrame.h"
#include "Page.h"
#include "ScrollingConstraints.h"
#include "ScrollingStateFixedNode.h"
#include "ScrollingStateScrollingNode.h"
#include "ScrollingStateStickyNode.h"
#include "ScrollingStateTree.h"

namespace WebCore {

AsyncScrollingCoordinator::AsyncScrollingCoordinator(Page* page)
    : ScrollingCoordinator(page)
    , m_updateNodeScrollPositionTimer(this, &AsyncScrollingCoordinator::updateScrollPositionAfterAsyncScrollTimerFired)
    , m_scrollingStateTree(ScrollingStateTree::create(this))
{
}

AsyncScrollingCoordinator::~AsyncScrollingCoordinator()
{
}

void AsyncScrollingCoordinator::scrollingStateTreePropertiesChanged()
{
    scheduleTreeStateCommit();
}

void AsyncScrollingCoordinator::frameViewLayoutUpdated(FrameView* frameView)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    // If there isn't a root node yet, don't do anything. We'll be called again after creating one.
    if (!m_scrollingStateTree->rootStateNode())
        return;

    // Compute the region of the page that we can't do fast scrolling for. This currently includes
    // all scrollable areas, such as subframes, overflow divs and list boxes. We need to do this even if the
    // frame view whose layout was updated is not the main frame.
    Region nonFastScrollableRegion = computeNonFastScrollableRegion(&m_page->mainFrame(), IntPoint());

    // In the future, we may want to have the ability to set non-fast scrolling regions for more than
    // just the root node. But right now, this concept only applies to the root.
    setNonFastScrollableRegionForNode(nonFastScrollableRegion, m_scrollingStateTree->rootStateNode());

    if (!coordinatesScrollingForFrameView(frameView))
        return;

    ScrollingStateScrollingNode* node = toScrollingStateScrollingNode(m_scrollingStateTree->stateNodeForID(frameView->scrollLayerID()));
    if (!node)
        return;

    Scrollbar* verticalScrollbar = frameView->verticalScrollbar();
    Scrollbar* horizontalScrollbar = frameView->horizontalScrollbar();
    setScrollbarPaintersFromScrollbarsForNode(verticalScrollbar, horizontalScrollbar, node);

    node->setFrameScaleFactor(frameView->frame().frameScaleFactor());
    node->setHeaderHeight(frameView->headerHeight());
    node->setFooterHeight(frameView->footerHeight());

    node->setScrollOrigin(frameView->scrollOrigin());
    node->setViewportRect(IntRect(IntPoint(), frameView->visibleContentRect().size()));
    node->setTotalContentsSize(frameView->totalContentsSize());

    ScrollableAreaParameters scrollParameters;
    scrollParameters.horizontalScrollElasticity = frameView->horizontalScrollElasticity();
    scrollParameters.verticalScrollElasticity = frameView->verticalScrollElasticity();
    scrollParameters.hasEnabledHorizontalScrollbar = horizontalScrollbar && horizontalScrollbar->enabled();
    scrollParameters.hasEnabledVerticalScrollbar = verticalScrollbar && verticalScrollbar->enabled();
    scrollParameters.horizontalScrollbarMode = frameView->horizontalScrollbarMode();
    scrollParameters.verticalScrollbarMode = frameView->verticalScrollbarMode();

    node->setScrollableAreaParameters(scrollParameters);
}

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

    if (!coordinatesScrollingForFrameView(frameView))
        return;

    // If the root layer does not have a ScrollingStateNode, then we should create one.
    ensureRootStateNodeForFrameView(frameView);
    ASSERT(m_scrollingStateTree->rootStateNode());

    ScrollingCoordinator::frameViewRootLayerDidChange(frameView);

    ScrollingStateScrollingNode* node = toScrollingStateScrollingNode(m_scrollingStateTree->stateNodeForID(frameView->scrollLayerID()));
    setScrollLayerForNode(scrollLayerForFrameView(frameView), node);
    setCounterScrollingLayerForNode(counterScrollingLayerForFrameView(frameView), node);
    setHeaderLayerForNode(headerLayerForFrameView(frameView), node);
    setFooterLayerForNode(footerLayerForFrameView(frameView), node);
    setScrollBehaviorForFixedElementsForNode(frameView->scrollBehaviorForFixedElements(), node);
}

bool AsyncScrollingCoordinator::requestScrollPositionUpdate(FrameView* frameView, const IntPoint& scrollPosition)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    if (!coordinatesScrollingForFrameView(frameView))
        return false;

    if (frameView->inProgrammaticScroll() || frameView->frame().document()->inPageCache())
        updateScrollPositionAfterAsyncScroll(frameView->scrollLayerID(), scrollPosition, frameView->inProgrammaticScroll(), SetScrollingLayerPosition);

    // If this frame view's document is being put into the page cache, we don't want to update our
    // main frame scroll position. Just let the FrameView think that we did.
    if (frameView->frame().document()->inPageCache())
        return true;

    ScrollingStateScrollingNode* stateNode = toScrollingStateScrollingNode(m_scrollingStateTree->stateNodeForID(frameView->scrollLayerID()));
    if (!stateNode)
        return false;

    stateNode->setRequestedScrollPosition(scrollPosition, frameView->inProgrammaticScroll());
    return true;
}

void AsyncScrollingCoordinator::scheduleUpdateScrollPositionAfterAsyncScroll(ScrollingNodeID nodeID, const IntPoint& scrollPosition, bool programmaticScroll, SetOrSyncScrollingLayerPosition scrollingLayerPositionAction)
{
    ScheduledScrollUpdate scrollUpdate(nodeID, scrollPosition, programmaticScroll, scrollingLayerPositionAction);
    
    if (m_updateNodeScrollPositionTimer.isActive()) {
        if (m_scheduledScrollUpdate.matchesUpdateType(scrollUpdate)) {
            m_scheduledScrollUpdate.scrollPosition = scrollPosition;
            return;
        }
    
        // If the parameters don't match what was previosly scheduled, dispatch immediately.
        m_updateNodeScrollPositionTimer.stop();
        updateScrollPositionAfterAsyncScroll(m_scheduledScrollUpdate.nodeID, m_scheduledScrollUpdate.scrollPosition, m_scheduledScrollUpdate.isProgrammaticScroll, m_scheduledScrollUpdate.updateLayerPositionAction);
        updateScrollPositionAfterAsyncScroll(nodeID, scrollPosition, programmaticScroll, scrollingLayerPositionAction);
        return;
    }

    m_scheduledScrollUpdate = scrollUpdate;
    m_updateNodeScrollPositionTimer.startOneShot(0);
}

void AsyncScrollingCoordinator::updateScrollPositionAfterAsyncScrollTimerFired(Timer<AsyncScrollingCoordinator>*)
{
    updateScrollPositionAfterAsyncScroll(m_scheduledScrollUpdate.nodeID, m_scheduledScrollUpdate.scrollPosition, m_scheduledScrollUpdate.isProgrammaticScroll, m_scheduledScrollUpdate.updateLayerPositionAction);
}

void AsyncScrollingCoordinator::updateScrollPositionAfterAsyncScroll(ScrollingNodeID scrollingNodeID, 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 (scrollingNodeID == frameView->scrollLayerID()) {
        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);
            }
        }
    }
    // FIXME: handle non-main scrolling nodes.
}

void AsyncScrollingCoordinator::scrollableAreaScrollbarLayerDidChange(ScrollableArea* scrollableArea, ScrollbarOrientation orientation)
{
    ASSERT(isMainThread());
    ASSERT(m_page);

    if (scrollableArea != static_cast<ScrollableArea*>(m_page->mainFrame().view()))
        return;

    if (orientation == VerticalScrollbar)
        scrollableArea->verticalScrollbarLayerDidChange();
    else
        scrollableArea->horizontalScrollbarLayerDidChange();
}

ScrollingNodeID AsyncScrollingCoordinator::attachToStateTree(ScrollingNodeType nodeType, ScrollingNodeID newNodeID, ScrollingNodeID parentID)
{
    return m_scrollingStateTree->attachNode(nodeType, newNodeID, parentID);
}

void AsyncScrollingCoordinator::detachFromStateTree(ScrollingNodeID nodeID)
{
    m_scrollingStateTree->detachNode(nodeID);
}

void AsyncScrollingCoordinator::clearStateTree()
{
    m_scrollingStateTree->clear();
}

void AsyncScrollingCoordinator::syncChildPositions(const LayoutRect& viewportRect)
{
    if (!m_scrollingStateTree->rootStateNode())
        return;

    Vector<OwnPtr<ScrollingStateNode>>* children = m_scrollingStateTree->rootStateNode()->children();
    if (!children)
        return;

    // FIXME: We'll have to traverse deeper into the tree at some point.
    size_t size = children->size();
    for (size_t i = 0; i < size; ++i) {
        ScrollingStateNode* child = children->at(i).get();
        child->syncLayerPositionForViewportRect(viewportRect);
    }
}

void AsyncScrollingCoordinator::ensureRootStateNodeForFrameView(FrameView* frameView)
{
    ASSERT(frameView->scrollLayerID());
    attachToStateTree(ScrollingNode, frameView->scrollLayerID(), 0);
}

void AsyncScrollingCoordinator::updateScrollingNode(ScrollingNodeID nodeID, GraphicsLayer* scrollLayer, GraphicsLayer* counterScrollingLayer)
{
    ScrollingStateScrollingNode* node = toScrollingStateScrollingNode(m_scrollingStateTree->stateNodeForID(nodeID));
    ASSERT(node);
    if (!node)
        return;

    node->setLayer(scrollLayer);
    node->setCounterScrollingLayer(counterScrollingLayer);
}

void AsyncScrollingCoordinator::updateViewportConstrainedNode(ScrollingNodeID nodeID, const ViewportConstraints& constraints, GraphicsLayer* graphicsLayer)
{
    ASSERT(supportsFixedPositionLayers());

    ScrollingStateNode* node = m_scrollingStateTree->stateNodeForID(nodeID);
    if (!node)
        return;

    switch (constraints.constraintType()) {
    case ViewportConstraints::FixedPositionConstraint: {
        ScrollingStateFixedNode* fixedNode = toScrollingStateFixedNode(node);
        setScrollLayerForNode(graphicsLayer, fixedNode);
        fixedNode->updateConstraints((const FixedPositionViewportConstraints&)constraints);
        break;
    }
    case ViewportConstraints::StickyPositionConstraint: {
        ScrollingStateStickyNode* stickyNode = toScrollingStateStickyNode(node);
        setScrollLayerForNode(graphicsLayer, stickyNode);
        stickyNode->updateConstraints((const StickyPositionViewportConstraints&)constraints);
        break;
    }
    }
}

void AsyncScrollingCoordinator::setScrollLayerForNode(GraphicsLayer* scrollLayer, ScrollingStateNode* node)
{
    node->setLayer(scrollLayer);
}

void AsyncScrollingCoordinator::setCounterScrollingLayerForNode(GraphicsLayer* layer, ScrollingStateScrollingNode* node)
{
    node->setCounterScrollingLayer(layer);
}

void AsyncScrollingCoordinator::setHeaderLayerForNode(GraphicsLayer* headerLayer, ScrollingStateScrollingNode* node)
{
    // Headers and footers are only supported on the root node.
    ASSERT(node == m_scrollingStateTree->rootStateNode());
    node->setHeaderLayer(headerLayer);
}

void AsyncScrollingCoordinator::setFooterLayerForNode(GraphicsLayer* footerLayer, ScrollingStateScrollingNode* node)
{
    // Headers and footers are only supported on the root node.
    ASSERT(node == m_scrollingStateTree->rootStateNode());
    node->setFooterLayer(footerLayer);
}

void AsyncScrollingCoordinator::setNonFastScrollableRegionForNode(const Region& region, ScrollingStateScrollingNode* node)
{
    node->setNonFastScrollableRegion(region);
}

void AsyncScrollingCoordinator::setWheelEventHandlerCountForNode(unsigned wheelEventHandlerCount, ScrollingStateScrollingNode* node)
{
    node->setWheelEventHandlerCount(wheelEventHandlerCount);
}

void AsyncScrollingCoordinator::setScrollBehaviorForFixedElementsForNode(ScrollBehaviorForFixedElements behaviorForFixed, ScrollingStateScrollingNode* node)
{
    node->setScrollBehaviorForFixedElements(behaviorForFixed);
}

// FIXME: not sure if this belongs here.
void AsyncScrollingCoordinator::setScrollbarPaintersFromScrollbarsForNode(Scrollbar* verticalScrollbar, Scrollbar* horizontalScrollbar, ScrollingStateScrollingNode* node)
{
    node->setScrollbarPaintersFromScrollbars(verticalScrollbar, horizontalScrollbar);
}

void AsyncScrollingCoordinator::setSynchronousScrollingReasons(SynchronousScrollingReasons reasons)
{
    if (!m_scrollingStateTree->rootStateNode())
        return;

    // The FrameView's GraphicsLayer is likely to be out-of-synch with the PlatformLayer
    // at this point. So we'll update it before we switch back to main thread scrolling
    // in order to avoid layer positioning bugs.
    if (reasons)
        updateMainFrameScrollLayerPosition();
    m_scrollingStateTree->rootStateNode()->setSynchronousScrollingReasons(reasons);
}

void AsyncScrollingCoordinator::updateMainFrameScrollLayerPosition()
{
    ASSERT(isMainThread());

    if (!m_page)
        return;

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

    if (GraphicsLayer* scrollLayer = scrollLayerForFrameView(frameView))
        scrollLayer->setPosition(-frameView->scrollPosition());
}

void AsyncScrollingCoordinator::recomputeWheelEventHandlerCountForFrameView(FrameView* frameView)
{
    ScrollingStateScrollingNode* node = toScrollingStateScrollingNode(m_scrollingStateTree->stateNodeForID(frameView->scrollLayerID()));
    if (!node)
        return;
    setWheelEventHandlerCountForNode(computeCurrentWheelEventHandlerCount(), node);
}

bool AsyncScrollingCoordinator::isRubberBandInProgress() const
{
    return scrollingTree()->isRubberBandInProgress();
}

void AsyncScrollingCoordinator::setScrollPinningBehavior(ScrollPinningBehavior pinning)
{
    scrollingTree()->setScrollPinningBehavior(pinning);
}

String AsyncScrollingCoordinator::scrollingStateTreeAsText() const
{
    if (m_scrollingStateTree->rootStateNode())
        return m_scrollingStateTree->rootStateNode()->scrollingStateTreeAsText();

    return String();
}

} // namespace WebCore

#endif // ENABLE(ASYNC_SCROLLING)