layout/generic/ScrollAnimationPhysics.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 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_layout_ScrollAnimationPhysics_h_
   8 #define mozilla_layout_ScrollAnimationPhysics_h_
   9
  10 #include "mozilla/TimeStamp.h"
  11 #include "nsPoint.h"
  12 #include "Units.h"
  13
  14 namespace mozilla {
  15
  16 class ScrollAnimationPhysics {
  17  public:
  18   virtual void Update(const TimeStamp& aTime, const nsPoint& aDestination,
  19                       const nsSize& aCurrentVelocity) = 0;
  20
  21   virtual void ApplyContentShift(const CSSPoint& aShiftDelta) = 0;
  22
  23   // Get the velocity at a point in time in nscoords/sec.
  24   virtual nsSize VelocityAt(const TimeStamp& aTime) = 0;
  25
  26   // Returns the expected scroll position at a given point in time, in app
  27   // units, relative to the scroll frame.
  28   virtual nsPoint PositionAt(const TimeStamp& aTime) = 0;
  29
  30   virtual bool IsFinished(const TimeStamp& aTime) = 0;
  31
  32   virtual ~ScrollAnimationPhysics() = default;
  33 };
  34
  35 // Helper for accelerated wheel deltas. This can be called from the main thread
  36 // or the APZ Controller thread.
  37 static inline double ComputeAcceleratedWheelDelta(double aDelta,
  38                                                   int32_t aCounter,
  39                                                   int32_t aFactor) {
  40   if (!aDelta) {
  41     return aDelta;
  42   }
  43   return (aDelta * aCounter * double(aFactor) / 10);
  44 }
  45
  46 static const uint32_t kScrollSeriesTimeoutMs = 80;  // in milliseconds
  47
  48 }  // namespace mozilla
  49
  50 #endif  // mozilla_layout_ScrollAnimationPhysics_h_