gfx/layers/apz/src/SampledAPZCState.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_layers_SampledAPZCState_h
   8 #define mozilla_layers_SampledAPZCState_h
   9
  10 #include "FrameMetrics.h"
  11 #include "mozilla/Maybe.h"
  12 #include "mozilla/ScrollGeneration.h"
  13
  14 namespace mozilla {
  15 namespace layers {
  16
  17 class SampledAPZCState {
  18  public:
  19   SampledAPZCState();
  20   explicit SampledAPZCState(const FrameMetrics& aMetrics);
  21   SampledAPZCState(const FrameMetrics& aMetrics,
  22                    Maybe<CompositionPayload>&& aPayload,
  23                    APZScrollGeneration aGeneration);
  24
  25   bool operator==(const SampledAPZCState& aOther) const;
  26   bool operator!=(const SampledAPZCState& aOther) const;
  27
  28   CSSRect GetLayoutViewport() const { return mLayoutViewport; }
  29   CSSPoint GetVisualScrollOffset() const { return mVisualScrollOffset; }
  30   CSSToParentLayerScale GetZoom() const { return mZoom; }
  31   Maybe<CompositionPayload> TakeScrollPayload();
  32   const APZScrollGeneration& Generation() const { return mGeneration; }
  33
  34   void UpdateScrollProperties(const FrameMetrics& aMetrics);
  35   void UpdateScrollPropertiesWithRelativeDelta(const FrameMetrics& aMetrics,
  36                                                const CSSPoint& aRelativeDelta);
  37
  38   void UpdateZoomProperties(const FrameMetrics& aMetrics);
  39
  40   /**
  41    * Re-clamp mVisualScrollOffset to the scroll range specified by the provided
  42    * metrics. This only needs to be called if the scroll offset changes
  43    * outside of AsyncPanZoomController::SampleCompositedAsyncTransform().
  44    * It also recalculates mLayoutViewport so that it continues to enclose
  45    * the visual viewport. This only needs to be called if the
  46    * layout viewport changes outside of SampleCompositedAsyncTransform().
  47    */
  48   void ClampVisualScrollOffset(const FrameMetrics& aMetrics);
  49
  50   void ZoomBy(float aScale);
  51
  52  private:
  53   // These variables cache the layout viewport, scroll offset, and zoom stored
  54   // in |Metrics()| at the time this class was constructed.
  55   CSSRect mLayoutViewport;
  56   CSSPoint mVisualScrollOffset;
  57   CSSToParentLayerScale mZoom;
  58   // An optional payload that rides along with the sampled state.
  59   Maybe<CompositionPayload> mScrollPayload;
  60   APZScrollGeneration mGeneration;
  61
  62   void RemoveFractionalAsyncDelta();
  63   // A handy wrapper to call
  64   // FrameMetrics::KeepLayoutViewportEnclosingVisualViewport with this
  65   // SampledAPZCState and the given |aMetrics|.
  66   void KeepLayoutViewportEnclosingVisualViewport(const FrameMetrics& aMetrics);
  67 };
  68
  69 }  // namespace layers
  70 }  // namespace mozilla
  71
  72 #endif  // mozilla_layers_SampledAPZCState_h