Source/WebCore/platform/ScrollAnimator.h

/*
 * Copyright (c) 2010, Google Inc. All rights reserved.
 * Copyright (C) 2015 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:
 * 
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "FloatPoint.h"
#include "PlatformWheelEvent.h"
#include "ScrollingEffectsController.h"
#include "Timer.h"
#include "WheelEventTestMonitor.h"
#include <wtf/FastMalloc.h>
#include <wtf/Forward.h>

namespace WebCore {

class FloatPoint;
class KeyboardScrollingAnimator;
class PlatformTouchEvent;
class ScrollAnimationSmooth;
class ScrollableArea;
class Scrollbar;
class WheelEventTestMonitor;

struct ScrollExtents;

class ScrollingEffectsControllerTimer;

class ScrollAnimator : private ScrollingEffectsControllerClient {
    WTF_MAKE_FAST_ALLOCATED;
public:
    static std::unique_ptr<ScrollAnimator> create(ScrollableArea&);

    explicit ScrollAnimator(ScrollableArea&);
    virtual ~ScrollAnimator();

    ScrollableArea& scrollableArea() const { return m_scrollableArea; }

    KeyboardScrollingAnimator *keyboardScrollingAnimator() const final { return m_keyboardScrollingAnimator.get(); }

    enum ScrollBehavior {
        DoDirectionalSnapping = 1 << 0,
        NeverAnimate = 1 << 1,
    };

    // Computes a scroll destination for the given parameters.  Returns false if
    // already at the destination.  Otherwise, starts scrolling towards the
    // destination and returns true.  Scrolling may be immediate or animated.
    // The base class implementation always scrolls immediately, never animates.
    bool scroll(ScrollbarOrientation, ScrollGranularity, float step, float multiplier, OptionSet<ScrollBehavior>);

    virtual bool scrollToPositionWithoutAnimation(const FloatPoint&, ScrollClamping = ScrollClamping::Clamped);
    bool scrollToPositionWithAnimation(const FloatPoint&);

    void retargetRunningAnimation(const FloatPoint& newPosition);

    virtual bool handleWheelEvent(const PlatformWheelEvent&);

    virtual bool processWheelEventForScrollSnap(const PlatformWheelEvent&) { return false; }

#if PLATFORM(COCOA)
    virtual void handleWheelEventPhase(PlatformWheelEventPhase) { }
#endif

#if ENABLE(TOUCH_EVENTS)
    virtual bool handleTouchEvent(const PlatformTouchEvent&);
#endif

    virtual void cancelAnimations();

    virtual bool isRubberBandInProgress() const { return false; }

    bool isUserScrollInProgress() const { return m_scrollController.isUserScrollInProgress(); }
    bool isScrollSnapInProgress() const { return m_scrollController.isScrollSnapInProgress(); }

    void contentsSizeChanged();

    enum NotifyScrollableArea : bool {
        No, Yes
    };
    void setCurrentPosition(const FloatPoint&, NotifyScrollableArea = NotifyScrollableArea::No);
    const FloatPoint& currentPosition() const { return m_currentPosition; }

    void setWheelEventTestMonitor(RefPtr<WheelEventTestMonitor>&& testMonitor) { m_wheelEventTestMonitor = testMonitor; }
    WheelEventTestMonitor* wheelEventTestMonitor() const { return m_wheelEventTestMonitor.get(); }

    FloatPoint scrollOffsetAdjustedForSnapping(const FloatPoint& offset, ScrollSnapPointSelectionMethod) const;
    float scrollOffsetAdjustedForSnapping(ScrollEventAxis, const FloatPoint& newOffset, ScrollSnapPointSelectionMethod) const;

    bool activeScrollSnapIndexDidChange() const;
    std::optional<unsigned> activeScrollSnapIndexForAxis(ScrollEventAxis) const;
    void setActiveScrollSnapIndexForAxis(ScrollEventAxis, std::optional<unsigned> index);
    void setSnapOffsetsInfo(const LayoutScrollSnapOffsetsInfo&);
    const LayoutScrollSnapOffsetsInfo* snapOffsetsInfo() const;
    void resnapAfterLayout();

protected:
    virtual bool platformAllowsScrollAnimation() const { return true; }

private:
    void notifyPositionChanged(const FloatSize& delta);

    void scrollControllerAnimationTimerFired();
    void updateActiveScrollSnapIndexForOffset();

    FloatPoint offsetFromPosition(const FloatPoint& position) const;
    FloatPoint positionFromOffset(const FloatPoint& offset) const;

    FloatPoint adjustScrollPositionIfNecessary(const FloatPoint&) const;

    // ScrollingEffectsControllerClient.
    std::unique_ptr<ScrollingEffectsControllerTimer> createTimer(Function<void()>&&) final;
    void startAnimationCallback(ScrollingEffectsController&) final;
    void stopAnimationCallback(ScrollingEffectsController&) final;

    FloatPoint scrollOffset() const final;
    float pageScaleFactor() const final;
    ScrollExtents scrollExtents() const final;

    bool allowsHorizontalScrolling() const final;
    bool allowsVerticalScrolling() const final;

    void willStartAnimatedScroll() final;
    void didStopAnimatedScroll() final;

    void immediateScrollBy(const FloatSize&, ScrollClamping = ScrollClamping::Clamped) final;
    void adjustScrollPositionToBoundsIfNecessary() final;

#if HAVE(RUBBER_BANDING)
    IntSize stretchAmount() const final;
    RectEdges<bool> edgePinnedState() const final;
    bool isPinnedOnSide(BoxSide) const final;
#endif

#if PLATFORM(MAC)
    void deferWheelEventTestCompletionForReason(WheelEventTestMonitor::ScrollableAreaIdentifier, WheelEventTestMonitor::DeferReason) const final;
    void removeWheelEventTestCompletionDeferralForReason(WheelEventTestMonitor::ScrollableAreaIdentifier, WheelEventTestMonitor::DeferReason) const final;
#endif

#if PLATFORM(GTK) || USE(NICOSIA)
    bool scrollAnimationEnabled() const final;
#endif

    static FloatSize deltaFromStep(ScrollbarOrientation, float step, float multiplier);

protected:
    ScrollableArea& m_scrollableArea;
    RefPtr<WheelEventTestMonitor> m_wheelEventTestMonitor;
    ScrollingEffectsController m_scrollController;
    Timer m_scrollControllerAnimationTimer;
    FloatPoint m_currentPosition;

    std::unique_ptr<KeyboardScrollingAnimator> m_keyboardScrollingAnimator;
};

} // namespace WebCore