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      1 /*
      2  * Copyright (C) 2011 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
     14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
     17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
     23  * THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef ScrollingCoordinator_h
     27 #define ScrollingCoordinator_h
     28 
     29 #include "core/rendering/RenderObject.h"
     30 #include "platform/PlatformWheelEvent.h"
     31 #include "platform/geometry/IntRect.h"
     32 #include "platform/scroll/ScrollTypes.h"
     33 #include "wtf/text/WTFString.h"
     34 
     35 namespace blink {
     36 class WebLayer;
     37 class WebScrollbarLayer;
     38 }
     39 
     40 namespace WebCore {
     41 
     42 typedef unsigned MainThreadScrollingReasons;
     43 
     44 class Document;
     45 class Frame;
     46 class FrameView;
     47 class GraphicsLayer;
     48 class Page;
     49 class Region;
     50 class ScrollableArea;
     51 class ViewportConstraints;
     52 
     53 class ScrollingCoordinator : public RefCounted<ScrollingCoordinator> {
     54 public:
     55     static PassRefPtr<ScrollingCoordinator> create(Page*);
     56     ~ScrollingCoordinator();
     57 
     58     void pageDestroyed();
     59 
     60     // Return whether this scrolling coordinator handles scrolling for the given frame view.
     61     bool coordinatesScrollingForFrameView(FrameView*) const;
     62 
     63     // Called when any frame has done its layout.
     64     void notifyLayoutUpdated();
     65 
     66     // Should be called after compositing has been updated.
     67     void updateAfterCompositingChange();
     68 
     69     bool needsToUpdateAfterCompositingChange() const { return m_scrollGestureRegionIsDirty || m_touchEventTargetRectsAreDirty || frameViewIsScrollableIsDirty(); }
     70 
     71     // Should be called whenever a wheel event handler is added or removed in the
     72     // frame view's underlying document.
     73     void frameViewWheelEventHandlerCountChanged(FrameView*);
     74 
     75     // Should be called whenever the slow repaint objects counter changes between zero and one.
     76     void frameViewHasSlowRepaintObjectsDidChange(FrameView*);
     77 
     78     // Should be called whenever the set of fixed objects changes.
     79     void frameViewFixedObjectsDidChange(FrameView*);
     80 
     81     // Should be called whenever the root layer for the given frame view changes.
     82     void frameViewRootLayerDidChange(FrameView*);
     83 
     84 #if OS(MACOSX)
     85     // Dispatched by the scrolling tree during handleWheelEvent. This is required as long as scrollbars are painted on the main thread.
     86     void handleWheelEventPhase(PlatformWheelEventPhase);
     87 #endif
     88 
     89     enum MainThreadScrollingReasonFlags {
     90         HasSlowRepaintObjects = 1 << 0,
     91         HasViewportConstrainedObjectsWithoutSupportingFixedLayers = 1 << 1,
     92         HasNonLayerViewportConstrainedObjects = 1 << 2,
     93     };
     94 
     95     MainThreadScrollingReasons mainThreadScrollingReasons() const;
     96     bool shouldUpdateScrollLayerPositionOnMainThread() const { return mainThreadScrollingReasons() != 0; }
     97 
     98     PassOwnPtr<blink::WebScrollbarLayer> createSolidColorScrollbarLayer(ScrollbarOrientation, int thumbThickness, bool isLeftSideVerticalScrollbar);
     99 
    100     void willDestroyScrollableArea(ScrollableArea*);
    101     // Returns true if the coordinator handled this change.
    102     bool scrollableAreaScrollLayerDidChange(ScrollableArea*);
    103     void scrollableAreaScrollbarLayerDidChange(ScrollableArea*, ScrollbarOrientation);
    104     void setLayerIsContainerForFixedPositionLayers(GraphicsLayer*, bool);
    105     void updateLayerPositionConstraint(RenderLayer*);
    106     void touchEventTargetRectsDidChange(const Document*);
    107     void willDestroyRenderLayer(RenderLayer*);
    108 
    109     void updateScrollParentForGraphicsLayer(GraphicsLayer* child, RenderLayer* parent);
    110     void updateClipParentForGraphicsLayer(GraphicsLayer* child, RenderLayer* parent);
    111 
    112     static String mainThreadScrollingReasonsAsText(MainThreadScrollingReasons);
    113     String mainThreadScrollingReasonsAsText() const;
    114     Region computeShouldHandleScrollGestureOnMainThreadRegion(const Frame*, const IntPoint& frameLocation) const;
    115 
    116     void updateTouchEventTargetRectsIfNeeded();
    117 
    118     // For testing purposes only. This ScrollingCoordinator is reused between layout test, and must be reset
    119     // for the results to be valid.
    120     void reset();
    121 
    122 protected:
    123     explicit ScrollingCoordinator(Page*);
    124 
    125     static GraphicsLayer* scrollLayerForScrollableArea(ScrollableArea*);
    126     static GraphicsLayer* horizontalScrollbarLayerForScrollableArea(ScrollableArea*);
    127     static GraphicsLayer* verticalScrollbarLayerForScrollableArea(ScrollableArea*);
    128     bool isForMainFrame(ScrollableArea*) const;
    129 
    130     unsigned computeCurrentWheelEventHandlerCount();
    131     GraphicsLayer* scrollLayerForFrameView(FrameView*);
    132     GraphicsLayer* counterScrollingLayerForFrameView(FrameView*);
    133 
    134     Page* m_page;
    135 
    136     // Dirty flags used to idenfity what really needs to be computed after compositing is updated.
    137     bool m_scrollGestureRegionIsDirty;
    138     bool m_touchEventTargetRectsAreDirty;
    139 
    140 private:
    141     void recomputeWheelEventHandlerCountForFrameView(FrameView*);
    142     void setShouldUpdateScrollLayerPositionOnMainThread(MainThreadScrollingReasons);
    143 
    144     bool hasVisibleSlowRepaintViewportConstrainedObjects(FrameView*) const;
    145     void updateShouldUpdateScrollLayerPositionOnMainThread();
    146 
    147     static blink::WebLayer* scrollingWebLayerForScrollableArea(ScrollableArea*);
    148 
    149     bool touchHitTestingEnabled() const;
    150     void setShouldHandleScrollGestureOnMainThreadRegion(const Region&);
    151     void setTouchEventTargetRects(const LayerHitTestRects&);
    152     void computeTouchEventTargetRects(LayerHitTestRects&);
    153     void setWheelEventHandlerCount(unsigned);
    154 
    155     blink::WebScrollbarLayer* addWebScrollbarLayer(ScrollableArea*, ScrollbarOrientation, PassOwnPtr<blink::WebScrollbarLayer>);
    156     blink::WebScrollbarLayer* getWebScrollbarLayer(ScrollableArea*, ScrollbarOrientation);
    157     void removeWebScrollbarLayer(ScrollableArea*, ScrollbarOrientation);
    158 
    159     bool frameViewIsScrollableIsDirty() const;
    160 
    161     typedef HashMap<ScrollableArea*, OwnPtr<blink::WebScrollbarLayer> > ScrollbarMap;
    162     ScrollbarMap m_horizontalScrollbars;
    163     ScrollbarMap m_verticalScrollbars;
    164     HashSet<const RenderLayer*> m_layersWithTouchRects;
    165     bool m_wasFrameScrollable;
    166 
    167     // This is retained for testing.
    168     MainThreadScrollingReasons m_lastMainThreadScrollingReasons;
    169 };
    170 
    171 } // namespace WebCore
    172 
    173 #endif // ScrollingCoordinator_h
    174