third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h

/*
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#ifndef ScrollAnimatorBase_h
#define ScrollAnimatorBase_h

#include "platform/PlatformExport.h"
#include "platform/PlatformWheelEvent.h"
#include "platform/geometry/FloatPoint.h"
#include "platform/geometry/FloatSize.h"
#include "platform/heap/Handle.h"
#include "platform/scroll/ScrollAnimatorCompositorCoordinator.h"
#include "platform/scroll/ScrollTypes.h"
#include "wtf/Forward.h"

namespace blink {

class CompositorAnimationTimeline;
class ScrollableArea;
class Scrollbar;

class PLATFORM_EXPORT ScrollAnimatorBase : public ScrollAnimatorCompositorCoordinator {
public:
    static ScrollAnimatorBase* create(ScrollableArea*);

    virtual ~ScrollAnimatorBase();

    virtual void dispose() { }

    // A possibly animated scroll. The base class implementation always scrolls
    // immediately, never animates. If the scroll is animated and currently the
    // animator has an in-progress animation, the ScrollResult will always return
    // no unusedDelta and didScroll=true, i.e. fully consuming the scroll request.
    // This makes animations latch to a single scroller. Note, the semantics are
    // currently somewhat different on Mac - see ScrollAnimatorMac.mm.
    virtual ScrollResult userScroll(ScrollGranularity, const FloatSize& delta);

    virtual void scrollToOffsetWithoutAnimation(const FloatPoint&);

#if OS(MACOSX)
    virtual void handleWheelEventPhase(PlatformWheelEventPhase) { }
#endif

    void setCurrentPosition(const FloatPoint&);
    FloatPoint currentPosition() const;
    virtual FloatPoint desiredTargetPosition() const { return currentPosition(); }

    // Returns how much of pixelDelta will be used by the underlying scrollable
    // area.
    virtual FloatSize computeDeltaToConsume(const FloatSize& delta) const;


    // ScrollAnimatorCompositorCoordinator implementation.
    ScrollableArea* getScrollableArea() const override { return m_scrollableArea; }
    void tickAnimation(double monotonicTime) override { };
    void cancelAnimation() override { }
    void takeOverCompositorAnimation() override { }
    void updateCompositorAnimations() override { };
    void notifyCompositorAnimationFinished(int groupId) override { };
    void notifyCompositorAnimationAborted(int groupId) override { };
    void layerForCompositedScrollingDidChange(CompositorAnimationTimeline*) override { };

    virtual void contentAreaWillPaint() const { }
    virtual void mouseEnteredContentArea() const { }
    virtual void mouseExitedContentArea() const { }
    virtual void mouseMovedInContentArea() const { }
    virtual void mouseEnteredScrollbar(Scrollbar&) const { }
    virtual void mouseExitedScrollbar(Scrollbar&) const { }
    virtual void updateAfterLayout() { }
    virtual void contentsResized() const { }
    virtual void contentAreaDidShow() const { }
    virtual void contentAreaDidHide() const { }

    virtual void finishCurrentScrollAnimations() { }

    virtual void didAddVerticalScrollbar(Scrollbar&) { }
    virtual void willRemoveVerticalScrollbar(Scrollbar&) { }
    virtual void didAddHorizontalScrollbar(Scrollbar&) { }
    virtual void willRemoveHorizontalScrollbar(Scrollbar&) { }

    virtual bool shouldScrollbarParticipateInHitTesting(Scrollbar&) { return true; }

    virtual void notifyContentAreaScrolled(const FloatSize&) { }

    virtual bool setScrollbarsVisibleForTesting(bool) { return false; }

    DECLARE_VIRTUAL_TRACE();

protected:
    explicit ScrollAnimatorBase(ScrollableArea*);

    virtual void notifyPositionChanged();

    Member<ScrollableArea> m_scrollableArea;

    FloatPoint m_currentPos;
};

} // namespace blink

#endif // ScrollAnimatorBase_h