1 files changed, 101 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/AsyncPanZoomAnimation.h b/gfx/layers/apz/src/AsyncPanZoomAnimation.h
new file mode 100644
index 0000000000..127667afd9
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+++ b/gfx/layers/apz/src/AsyncPanZoomAnimation.h
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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 http://mozilla.org/MPL/2.0/. */
+
+#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 {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AsyncPanZoomAnimation)
+
+ public:
+  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:
+  // 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_