1 files changed, 137 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/Overscroll.h b/gfx/layers/apz/src/Overscroll.h
new file mode 100644
index 000000000..586f104cc
--- /dev/null
+++ b/gfx/layers/apz/src/Overscroll.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et 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_Overscroll_h
+#define mozilla_layers_Overscroll_h
+
+#include "AsyncPanZoomAnimation.h"
+#include "AsyncPanZoomController.h"
+#include "FrameMetrics.h"
+#include "mozilla/TimeStamp.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace layers {
+
+// Animation used by GenericOverscrollEffect.
+class OverscrollAnimation: public AsyncPanZoomAnimation {
+public:
+  explicit OverscrollAnimation(AsyncPanZoomController& aApzc, const ParentLayerPoint& aVelocity)
+    : mApzc(aApzc)
+  {
+    mApzc.mX.StartOverscrollAnimation(aVelocity.x);
+    mApzc.mY.StartOverscrollAnimation(aVelocity.y);
+  }
+  ~OverscrollAnimation()
+  {
+    mApzc.mX.EndOverscrollAnimation();
+    mApzc.mY.EndOverscrollAnimation();
+  }
+
+  virtual bool DoSample(FrameMetrics& aFrameMetrics,
+                        const TimeDuration& aDelta) override
+  {
+    // Can't inline these variables due to short-circuit evaluation.
+    bool continueX = mApzc.mX.SampleOverscrollAnimation(aDelta);
+    bool continueY = mApzc.mY.SampleOverscrollAnimation(aDelta);
+    if (!continueX && !continueY) {
+      // If we got into overscroll from a fling, that fling did not request a
+      // fling snap to avoid a resulting scrollTo from cancelling the overscroll
+      // animation too early. We do still want to request a fling snap, though,
+      // in case the end of the axis at which we're overscrolled is not a valid
+      // snap point, so we request one now. If there are no snap points, this will
+      // do nothing. If there are snap points, we'll get a scrollTo that snaps us
+      // back to the nearest valid snap point.
+      // The scroll snapping is done in a deferred task, otherwise the state
+      // change to NOTHING caused by the overscroll animation ending would
+      // clobber a possible state change to SMOOTH_SCROLL in ScrollSnap().
+      mDeferredTasks.AppendElement(NewRunnableMethod(&mApzc, &AsyncPanZoomController::ScrollSnap));
+      return false;
+    }
+    return true;
+  }
+
+  virtual bool WantsRepaints() override
+  {
+    return false;
+  }
+
+private:
+  AsyncPanZoomController& mApzc;
+};
+
+// Base class for different overscroll effects;
+class OverscrollEffectBase {
+public:
+  virtual ~OverscrollEffectBase() {}
+  virtual void ConsumeOverscroll(ParentLayerPoint& aOverscroll,
+                                 bool aShouldOverscrollX,
+                                 bool aShouldOverscrollY) = 0;
+  virtual void HandleFlingOverscroll(const ParentLayerPoint& aVelocity) = 0;
+};
+
+// A generic overscroll effect, implemented by AsyncPanZoomController itself.
+class GenericOverscrollEffect : public OverscrollEffectBase {
+public:
+  explicit GenericOverscrollEffect(AsyncPanZoomController& aApzc) : mApzc(aApzc) {}
+
+  void ConsumeOverscroll(ParentLayerPoint& aOverscroll,
+                         bool aShouldOverscrollX,
+                         bool aShouldOverscrollY) override {
+    if (aShouldOverscrollX) {
+      mApzc.mX.OverscrollBy(aOverscroll.x);
+      aOverscroll.x = 0;
+    }
+
+    if (aShouldOverscrollY) {
+      mApzc.mY.OverscrollBy(aOverscroll.y);
+      aOverscroll.y = 0;
+    }
+
+    if (aShouldOverscrollX || aShouldOverscrollY) {
+      mApzc.ScheduleComposite();
+    }
+  }
+
+  void HandleFlingOverscroll(const ParentLayerPoint& aVelocity) override {
+    mApzc.StartOverscrollAnimation(aVelocity);
+  }
+
+private:
+  AsyncPanZoomController& mApzc;
+};
+
+// A widget-specific overscroll effect, implemented by the widget via
+// GeckoContentController.
+class WidgetOverscrollEffect : public OverscrollEffectBase {
+public:
+  explicit WidgetOverscrollEffect(AsyncPanZoomController& aApzc) : mApzc(aApzc) {}
+
+  void ConsumeOverscroll(ParentLayerPoint& aOverscroll,
+                         bool aShouldOverscrollX,
+                         bool aShouldOverscrollY) override {
+    RefPtr<GeckoContentController> controller = mApzc.GetGeckoContentController();
+    if (controller && (aShouldOverscrollX || aShouldOverscrollY)) {
+      controller->UpdateOverscrollOffset(aOverscroll.x, aOverscroll.y, mApzc.IsRootContent());
+      aOverscroll = ParentLayerPoint();
+    }
+  }
+
+  void HandleFlingOverscroll(const ParentLayerPoint& aVelocity) override {
+    RefPtr<GeckoContentController> controller = mApzc.GetGeckoContentController();
+    if (controller) {
+      controller->UpdateOverscrollVelocity(aVelocity.x, aVelocity.y, mApzc.IsRootContent());
+    }
+  }
+
+private:
+  AsyncPanZoomController& mApzc;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif // mozilla_layers_Overscroll_h