SampledAPZCState.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_SampledAPZCState_h

#define mozilla_layers_SampledAPZCState_h

#include "FrameMetrics.h"

#include "mozilla/Maybe.h"

#include "mozilla/ScrollGeneration.h"

namespace mozilla {

namespace layers {

class SampledAPZCState {

 public:

  SampledAPZCState();

  explicit SampledAPZCState(const FrameMetrics& aMetrics);

  SampledAPZCState(const FrameMetrics& aMetrics,

                   Maybe<CompositionPayload>&& aPayload,

                   APZScrollGeneration aGeneration);

  bool operator==(const SampledAPZCState& aOther) const;

  bool operator!=(const SampledAPZCState& aOther) const;

  CSSRect GetLayoutViewport() const { return mLayoutViewport; }

  CSSPoint GetVisualScrollOffset() const { return mVisualScrollOffset; }

  CSSToParentLayerScale GetZoom() const { return mZoom; }

  Maybe<CompositionPayload> TakeScrollPayload();

  const APZScrollGeneration& Generation() const { return mGeneration; }

  void UpdateScrollProperties(const FrameMetrics& aMetrics);

  void UpdateScrollPropertiesWithRelativeDelta(const FrameMetrics& aMetrics,

                                               const CSSPoint& aRelativeDelta);

  void UpdateZoomProperties(const FrameMetrics& aMetrics);

/**

   * Re-clamp mVisualScrollOffset to the scroll range specified by the provided

   * metrics. This only needs to be called if the scroll offset changes

   * outside of AsyncPanZoomController::SampleCompositedAsyncTransform().

   * It also recalculates mLayoutViewport so that it continues to enclose

   * the visual viewport. This only needs to be called if the

   * layout viewport changes outside of SampleCompositedAsyncTransform().

*/

  void ClampVisualScrollOffset(const FrameMetrics& aMetrics);

  void ZoomBy(float aScale);

 private:

  // These variables cache the layout viewport, scroll offset, and zoom stored

  // in |Metrics()| at the time this class was constructed.

  CSSRect mLayoutViewport;

  CSSPoint mVisualScrollOffset;

  CSSToParentLayerScale mZoom;

  // An optional payload that rides along with the sampled state.

  Maybe<CompositionPayload> mScrollPayload;

  APZScrollGeneration mGeneration;

  void RemoveFractionalAsyncDelta();

  // A handy wrapper to call

  // FrameMetrics::KeepLayoutViewportEnclosingVisualViewport with this

  // SampledAPZCState and the given |aMetrics|.

  void KeepLayoutViewportEnclosingVisualViewport(const FrameMetrics& aMetrics);

};

}  // namespace layers

}  // namespace mozilla

#endif  // mozilla_layers_SampledAPZCState_h