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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set sw=2 ts=8 et tw=80 : */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #ifndef mozilla_layers_Overscroll_h
       8             : #define mozilla_layers_Overscroll_h
       9             : 
      10             : #include "AsyncPanZoomAnimation.h"
      11             : #include "AsyncPanZoomController.h"
      12             : #include "FrameMetrics.h"
      13             : #include "mozilla/TimeStamp.h"
      14             : #include "nsThreadUtils.h"
      15             : 
      16             : namespace mozilla {
      17             : namespace layers {
      18             : 
      19             : // Animation used by GenericOverscrollEffect.
      20             : class OverscrollAnimation: public AsyncPanZoomAnimation {
      21             : public:
      22           0 :   explicit OverscrollAnimation(AsyncPanZoomController& aApzc, const ParentLayerPoint& aVelocity)
      23           0 :     : mApzc(aApzc)
      24             :   {
      25           0 :     mApzc.mX.StartOverscrollAnimation(aVelocity.x);
      26           0 :     mApzc.mY.StartOverscrollAnimation(aVelocity.y);
      27           0 :   }
      28           0 :   ~OverscrollAnimation()
      29           0 :   {
      30           0 :     mApzc.mX.EndOverscrollAnimation();
      31           0 :     mApzc.mY.EndOverscrollAnimation();
      32           0 :   }
      33             : 
      34           0 :   virtual bool DoSample(FrameMetrics& aFrameMetrics,
      35             :                         const TimeDuration& aDelta) override
      36             :   {
      37             :     // Can't inline these variables due to short-circuit evaluation.
      38           0 :     bool continueX = mApzc.mX.SampleOverscrollAnimation(aDelta);
      39           0 :     bool continueY = mApzc.mY.SampleOverscrollAnimation(aDelta);
      40           0 :     if (!continueX && !continueY) {
      41             :       // If we got into overscroll from a fling, that fling did not request a
      42             :       // fling snap to avoid a resulting scrollTo from cancelling the overscroll
      43             :       // animation too early. We do still want to request a fling snap, though,
      44             :       // in case the end of the axis at which we're overscrolled is not a valid
      45             :       // snap point, so we request one now. If there are no snap points, this will
      46             :       // do nothing. If there are snap points, we'll get a scrollTo that snaps us
      47             :       // back to the nearest valid snap point.
      48             :       // The scroll snapping is done in a deferred task, otherwise the state
      49             :       // change to NOTHING caused by the overscroll animation ending would
      50             :       // clobber a possible state change to SMOOTH_SCROLL in ScrollSnap().
      51           0 :       mDeferredTasks.AppendElement(
      52           0 :         NewRunnableMethod("layers::AsyncPanZoomController::ScrollSnap",
      53           0 :                           &mApzc,
      54           0 :                           &AsyncPanZoomController::ScrollSnap));
      55           0 :       return false;
      56             :     }
      57           0 :     return true;
      58             :   }
      59             : 
      60           0 :   virtual bool WantsRepaints() override
      61             :   {
      62           0 :     return false;
      63             :   }
      64             : 
      65             : private:
      66             :   AsyncPanZoomController& mApzc;
      67             : };
      68             : 
      69             : // Base class for different overscroll effects;
      70           2 : class OverscrollEffectBase {
      71             : public:
      72           0 :   virtual ~OverscrollEffectBase() {}
      73             :   virtual void ConsumeOverscroll(ParentLayerPoint& aOverscroll,
      74             :                                  bool aShouldOverscrollX,
      75             :                                  bool aShouldOverscrollY) = 0;
      76             :   virtual void HandleFlingOverscroll(const ParentLayerPoint& aVelocity) = 0;
      77             : };
      78             : 
      79             : // A generic overscroll effect, implemented by AsyncPanZoomController itself.
      80           0 : class GenericOverscrollEffect : public OverscrollEffectBase {
      81             : public:
      82           2 :   explicit GenericOverscrollEffect(AsyncPanZoomController& aApzc) : mApzc(aApzc) {}
      83             : 
      84           0 :   void ConsumeOverscroll(ParentLayerPoint& aOverscroll,
      85             :                          bool aShouldOverscrollX,
      86             :                          bool aShouldOverscrollY) override {
      87           0 :     if (aShouldOverscrollX) {
      88           0 :       mApzc.mX.OverscrollBy(aOverscroll.x);
      89           0 :       aOverscroll.x = 0;
      90             :     }
      91             : 
      92           0 :     if (aShouldOverscrollY) {
      93           0 :       mApzc.mY.OverscrollBy(aOverscroll.y);
      94           0 :       aOverscroll.y = 0;
      95             :     }
      96             : 
      97           0 :     if (aShouldOverscrollX || aShouldOverscrollY) {
      98           0 :       mApzc.ScheduleComposite();
      99             :     }
     100           0 :   }
     101             : 
     102           0 :   void HandleFlingOverscroll(const ParentLayerPoint& aVelocity) override {
     103           0 :     mApzc.StartOverscrollAnimation(aVelocity);
     104           0 :   }
     105             : 
     106             : private:
     107             :   AsyncPanZoomController& mApzc;
     108             : };
     109             : 
     110             : // A widget-specific overscroll effect, implemented by the widget via
     111             : // GeckoContentController.
     112             : class WidgetOverscrollEffect : public OverscrollEffectBase {
     113             : public:
     114             :   explicit WidgetOverscrollEffect(AsyncPanZoomController& aApzc) : mApzc(aApzc) {}
     115             : 
     116             :   void ConsumeOverscroll(ParentLayerPoint& aOverscroll,
     117             :                          bool aShouldOverscrollX,
     118             :                          bool aShouldOverscrollY) override {
     119             :     RefPtr<GeckoContentController> controller = mApzc.GetGeckoContentController();
     120             :     if (controller && (aShouldOverscrollX || aShouldOverscrollY)) {
     121             :       controller->UpdateOverscrollOffset(aOverscroll.x, aOverscroll.y, mApzc.IsRootContent());
     122             :       aOverscroll = ParentLayerPoint();
     123             :     }
     124             :   }
     125             : 
     126             :   void HandleFlingOverscroll(const ParentLayerPoint& aVelocity) override {
     127             :     RefPtr<GeckoContentController> controller = mApzc.GetGeckoContentController();
     128             :     if (controller) {
     129             :       controller->UpdateOverscrollVelocity(aVelocity.x, aVelocity.y, mApzc.IsRootContent());
     130             :     }
     131             :   }
     132             : 
     133             : private:
     134             :   AsyncPanZoomController& mApzc;
     135             : };
     136             : 
     137             : } // namespace layers
     138             : } // namespace mozilla
     139             : 
     140             : #endif // mozilla_layers_Overscroll_h