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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef mozilla_layers_AsyncPanZoomAnimation_h_
#define mozilla_layers_AsyncPanZoomAnimation_h_
#include "APZUtils.h"
#include "mozilla/RefPtr.h"
#include "mozilla/TimeStamp.h"
#include "nsISupportsImpl.h"
#include "nsTArray.h"
#include "nsThreadUtils.h"
namespace mozilla {
namespace layers {
struct FrameMetrics;
class WheelScrollAnimation;
class OverscrollAnimation;
class SmoothMsdScrollAnimation;
class SmoothScrollAnimation;
class AsyncPanZoomAnimation {
explicit AsyncPanZoomAnimation() = default;
virtual bool DoSample(FrameMetrics& aFrameMetrics,
const TimeDuration& aDelta) = 0;
* Attempt to handle a main-thread scroll offset update without cancelling
* the animation. This may or may not make sense depending on the type of
* the animation and whether the scroll update is relative or absolute.
* If the scroll update is relative, |aRelativeDelta| will contain the
* delta of the relative update. If the scroll update is absolute,
* |aRelativeDelta| will be Nothing() (the animation can check the APZC's
* FrameMetrics for the new absolute scroll offset if it wants to handle
* and absolute update).
* Returns whether the animation could handle the scroll update. If the
* return value is false, the animation will be cancelled.
virtual bool HandleScrollOffsetUpdate(const Maybe<CSSPoint>& aRelativeDelta) {
return false;
bool Sample(FrameMetrics& aFrameMetrics, const TimeDuration& aDelta) {
// In some situations, particularly when handoff is involved, it's possible
// for |aDelta| to be negative on the first call to sample. Ignore such a
// sample here, to avoid each derived class having to deal with this case.
if (aDelta.ToMilliseconds() <= 0) {
return true;
return DoSample(aFrameMetrics, aDelta);
* Get the deferred tasks in |mDeferredTasks| and place them in |aTasks|. See
* |mDeferredTasks| for more information. Clears |mDeferredTasks|.
nsTArray<RefPtr<Runnable>> TakeDeferredTasks() {
return std::move(mDeferredTasks);
virtual WheelScrollAnimation* AsWheelScrollAnimation() { return nullptr; }
virtual SmoothMsdScrollAnimation* AsSmoothMsdScrollAnimation() {
return nullptr;
virtual SmoothScrollAnimation* AsSmoothScrollAnimation() { return nullptr; }
virtual OverscrollAnimation* AsOverscrollAnimation() { return nullptr; }
virtual bool WantsRepaints() { return true; }
virtual void Cancel(CancelAnimationFlags aFlags) {}
virtual bool WasTriggeredByScript() const { return false; }
// Protected destructor, to discourage deletion outside of Release():
virtual ~AsyncPanZoomAnimation() = default;
* Tasks scheduled for execution after the APZC's mMonitor is released.
* Derived classes can add tasks here in Sample(), and the APZC can call
* ExecuteDeferredTasks() to execute them.
nsTArray<RefPtr<Runnable>> mDeferredTasks;
} // namespace layers
} // namespace mozilla
#endif // mozilla_layers_AsyncPanZoomAnimation_h_