gecko-dev/gfx/layers/LayerAttributes.h

/* -*- 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_gfx_layers_LayerAttributes_h
#define mozilla_gfx_layers_LayerAttributes_h

#include "FrameMetrics.h"
#include "mozilla/Maybe.h"
#include "mozilla/gfx/Types.h"
#include "mozilla/layers/LayersTypes.h"
#include "mozilla/layers/ScrollableLayerGuid.h"

namespace IPC {
template <typename T>
struct ParamTraits;
}  // namespace IPC

namespace mozilla {
namespace layers {

// clang-format off
MOZ_DEFINE_ENUM_CLASS_WITH_BASE(ScrollbarLayerType, uint8_t, (
  None,
  Thumb,
  Container
));
// clang-format on

/**
 *  It stores data for scroll thumb layer or container layers.
 */
struct ScrollbarData {
 private:
  /**
   * This constructor is for Thumb layer type.
   */
  ScrollbarData(ScrollDirection aDirection, float aThumbRatio,
                CSSCoord aThumbStart, CSSCoord aThumbLength,
                bool aThumbIsAsyncDraggable, CSSCoord aScrollTrackStart,
                CSSCoord aScrollTrackLength, uint64_t aTargetViewId)
      : mDirection(Some(aDirection)),
        mScrollbarLayerType(ScrollbarLayerType::Thumb),
        mThumbRatio(aThumbRatio),
        mThumbStart(aThumbStart),
        mThumbLength(aThumbLength),
        mThumbIsAsyncDraggable(aThumbIsAsyncDraggable),
        mScrollTrackStart(aScrollTrackStart),
        mScrollTrackLength(aScrollTrackLength),
        mTargetViewId(aTargetViewId) {}

  /**
   * This constructor is for Container layer type.
   */
  ScrollbarData(const Maybe<ScrollDirection>& aDirection,
                uint64_t aTargetViewId)
      : mDirection(aDirection),
        mScrollbarLayerType(ScrollbarLayerType::Container),
        mTargetViewId(aTargetViewId) {}

 public:
  ScrollbarData() = default;

  static ScrollbarData CreateForThumb(ScrollDirection aDirection,
                                      float aThumbRatio, CSSCoord aThumbStart,
                                      CSSCoord aThumbLength,
                                      bool aThumbIsAsyncDraggable,
                                      CSSCoord aScrollTrackStart,
                                      CSSCoord aScrollTrackLength,
                                      uint64_t aTargetViewId) {
    return ScrollbarData(aDirection, aThumbRatio, aThumbStart, aThumbLength,
                         aThumbIsAsyncDraggable, aScrollTrackStart,
                         aScrollTrackLength, aTargetViewId);
  }

  static ScrollbarData CreateForScrollbarContainer(
      const Maybe<ScrollDirection>& aDirection, uint64_t aTargetViewId) {
    return ScrollbarData(aDirection, aTargetViewId);
  }

  /**
   * The mDirection contains a direction if mScrollbarLayerType is Thumb
   * or Container, otherwise it's empty.
   */
  Maybe<ScrollDirection> mDirection;

  /**
   * Indicate what kind of layer this data is for. All possibilities are defined
   * in enum ScrollbarLayerType
   */
  ScrollbarLayerType mScrollbarLayerType = ScrollbarLayerType::None;

  /**
   * The scrollbar thumb ratio is the ratio of the thumb position (in the CSS
   * pixels of the scrollframe's parent's space) to the scroll position (in the
   * CSS pixels of the scrollframe's space).
   */
  float mThumbRatio = 0.0f;

  CSSCoord mThumbStart;
  CSSCoord mThumbLength;

  /**
   * Whether the scrollbar thumb can be dragged asynchronously.
   */
  bool mThumbIsAsyncDraggable = false;

  CSSCoord mScrollTrackStart;
  CSSCoord mScrollTrackLength;
  uint64_t mTargetViewId = ScrollableLayerGuid::NULL_SCROLL_ID;

  bool operator==(const ScrollbarData& aOther) const {
    return mDirection == aOther.mDirection &&
           mScrollbarLayerType == aOther.mScrollbarLayerType &&
           mThumbRatio == aOther.mThumbRatio &&
           mThumbStart == aOther.mThumbStart &&
           mThumbLength == aOther.mThumbLength &&
           mThumbIsAsyncDraggable == aOther.mThumbIsAsyncDraggable &&
           mScrollTrackStart == aOther.mScrollTrackStart &&
           mScrollTrackLength == aOther.mScrollTrackLength &&
           mTargetViewId == aOther.mTargetViewId;
  }
  bool operator!=(const ScrollbarData& aOther) const {
    return !(*this == aOther);
  }

  bool IsThumb() const {
    return mScrollbarLayerType == ScrollbarLayerType::Thumb;
  }
};

/**
 * Infrequently changing layer attributes.
 */
class SimpleLayerAttributes final {
  friend struct IPC::ParamTraits<mozilla::layers::SimpleLayerAttributes>;

 public:
  SimpleLayerAttributes()
      : mTransformIsPerspective(false),
        mPostXScale(1.0f),
        mPostYScale(1.0f),
        mContentFlags(0),
        mOpacity(1.0f),
        mIsFixedPosition(false),
        mMixBlendMode(gfx::CompositionOp::OP_OVER),
        mForceIsolatedGroup(false) {}

  /**
   * Setters.
   * All set methods return true if values changed, false otherwise.
   */

  bool SetPostScale(float aXScale, float aYScale) {
    if (mPostXScale == aXScale && mPostYScale == aYScale) {
      return false;
    }
    mPostXScale = aXScale;
    mPostYScale = aYScale;
    return true;
  }

  bool SetContentFlags(uint32_t aFlags) {
    if (aFlags == mContentFlags) {
      return false;
    }
    mContentFlags = aFlags;
    return true;
  }

  bool SetOpacity(float aOpacity) {
    if (aOpacity == mOpacity) {
      return false;
    }
    mOpacity = aOpacity;
    return true;
  }

  bool SetIsFixedPosition(bool aFixedPosition) {
    if (mIsFixedPosition == aFixedPosition) {
      return false;
    }
    mIsFixedPosition = aFixedPosition;
    return true;
  }

  bool SetAsyncZoomContainerId(const Maybe<FrameMetrics::ViewID>& aViewId) {
    if (mAsyncZoomContainerId == aViewId) {
      return false;
    }
    mAsyncZoomContainerId = aViewId;
    return true;
  }

  bool SetScrollbarData(const ScrollbarData& aScrollbarData) {
    if (mScrollbarData == aScrollbarData) {
      return false;
    }
    mScrollbarData = aScrollbarData;
    return true;
  }

  bool SetMixBlendMode(gfx::CompositionOp aMixBlendMode) {
    if (mMixBlendMode == aMixBlendMode) {
      return false;
    }
    mMixBlendMode = aMixBlendMode;
    return true;
  }

  bool SetForceIsolatedGroup(bool aForceIsolatedGroup) {
    if (mForceIsolatedGroup == aForceIsolatedGroup) {
      return false;
    }
    mForceIsolatedGroup = aForceIsolatedGroup;
    return true;
  }

  bool SetTransform(const gfx::Matrix4x4& aMatrix) {
    if (mTransform == aMatrix) {
      return false;
    }
    mTransform = aMatrix;
    return true;
  }

  bool SetTransformIsPerspective(bool aIsPerspective) {
    if (mTransformIsPerspective == aIsPerspective) {
      return false;
    }
    mTransformIsPerspective = aIsPerspective;
    return true;
  }

  bool SetFixedPositionData(ScrollableLayerGuid::ViewID aTargetViewId,
                            const LayerPoint& aAnchor, SideBits aSides) {
    if (mFixedPositionData && mFixedPositionData->mScrollId == aTargetViewId &&
        mFixedPositionData->mAnchor == aAnchor &&
        mFixedPositionData->mSides == aSides) {
      return false;
    }
    if (!mFixedPositionData) {
      mFixedPositionData.emplace();
    }
    mFixedPositionData->mScrollId = aTargetViewId;
    mFixedPositionData->mAnchor = aAnchor;
    mFixedPositionData->mSides = aSides;
    return true;
  }

  bool SetStickyPositionData(ScrollableLayerGuid::ViewID aScrollId,
                             LayerRectAbsolute aOuter,
                             LayerRectAbsolute aInner) {
    if (mStickyPositionData &&
        mStickyPositionData->mOuter.IsEqualEdges(aOuter) &&
        mStickyPositionData->mInner.IsEqualEdges(aInner)) {
      return false;
    }
    if (!mStickyPositionData) {
      mStickyPositionData.emplace();
    }
    mStickyPositionData->mScrollId = aScrollId;
    mStickyPositionData->mOuter = aOuter;
    mStickyPositionData->mInner = aInner;
    return true;
  }

  /**
   * This returns true if scrolling info is equivalent for the purposes of
   * APZ hit testing.
   */
  bool HitTestingInfoIsEqual(const SimpleLayerAttributes& aOther) const {
    if (mScrollbarData != aOther.mScrollbarData) {
      return false;
    }
    if (GetFixedPositionScrollContainerId() !=
        aOther.GetFixedPositionScrollContainerId()) {
      return false;
    }
    if (mTransform != aOther.mTransform) {
      return false;
    }
    return true;
  }

  /**
   * Getters.
   */

  float GetPostXScale() const { return mPostXScale; }

  float GetPostYScale() const { return mPostYScale; }

  uint32_t GetContentFlags() const { return mContentFlags; }

  float GetOpacity() const { return mOpacity; }

  bool IsFixedPosition() const { return mIsFixedPosition; }

  Maybe<FrameMetrics::ViewID> GetAsyncZoomContainerId() const {
    return mAsyncZoomContainerId;
  }

  const ScrollbarData& GetScrollbarData() const { return mScrollbarData; }

  gfx::CompositionOp GetMixBlendMode() const { return mMixBlendMode; }

  bool GetForceIsolatedGroup() const { return mForceIsolatedGroup; }

  const gfx::Matrix4x4& GetTransform() const { return mTransform; }

  bool GetTransformIsPerspective() const { return mTransformIsPerspective; }

  ScrollableLayerGuid::ViewID GetFixedPositionScrollContainerId() const {
    return (mIsFixedPosition && mFixedPositionData)
               ? mFixedPositionData->mScrollId
               : ScrollableLayerGuid::NULL_SCROLL_ID;
  }

  LayerPoint GetFixedPositionAnchor() const {
    return mFixedPositionData ? mFixedPositionData->mAnchor : LayerPoint();
  }

  SideBits GetFixedPositionSides() const {
    return mFixedPositionData ? mFixedPositionData->mSides : SideBits::eNone;
  }

  bool IsStickyPosition() const { return !!mStickyPositionData; }

  ScrollableLayerGuid::ViewID GetStickyScrollContainerId() const {
    return mStickyPositionData->mScrollId;
  }

  const LayerRectAbsolute& GetStickyScrollRangeOuter() const {
    return mStickyPositionData->mOuter;
  }

  const LayerRectAbsolute& GetStickyScrollRangeInner() const {
    return mStickyPositionData->mInner;
  }

  bool operator==(const SimpleLayerAttributes& aOther) const {
    return mTransform == aOther.mTransform &&
           mTransformIsPerspective == aOther.mTransformIsPerspective &&
           mPostXScale == aOther.mPostXScale &&
           mPostYScale == aOther.mPostYScale &&
           mContentFlags == aOther.mContentFlags &&
           mOpacity == aOther.mOpacity &&
           mIsFixedPosition == aOther.mIsFixedPosition &&
           mAsyncZoomContainerId == aOther.mAsyncZoomContainerId &&
           mScrollbarData == aOther.mScrollbarData &&
           mMixBlendMode == aOther.mMixBlendMode &&
           mForceIsolatedGroup == aOther.mForceIsolatedGroup;
  }

 private:
  gfx::Matrix4x4 mTransform;
  bool mTransformIsPerspective;
  float mPostXScale;
  float mPostYScale;
  uint32_t mContentFlags;
  float mOpacity;
  bool mIsFixedPosition;
  Maybe<FrameMetrics::ViewID> mAsyncZoomContainerId;
  ScrollbarData mScrollbarData;
  gfx::CompositionOp mMixBlendMode;
  bool mForceIsolatedGroup;

  struct FixedPositionData {
    ScrollableLayerGuid::ViewID mScrollId;
    LayerPoint mAnchor;
    SideBits mSides;
  };
  Maybe<FixedPositionData> mFixedPositionData;
  friend struct IPC::ParamTraits<
      mozilla::layers::SimpleLayerAttributes::FixedPositionData>;

  struct StickyPositionData {
    ScrollableLayerGuid::ViewID mScrollId;
    LayerRectAbsolute mOuter;
    LayerRectAbsolute mInner;
  };
  Maybe<StickyPositionData> mStickyPositionData;
  friend struct IPC::ParamTraits<
      mozilla::layers::SimpleLayerAttributes::StickyPositionData>;

  // Make sure to add new members to operator== and the ParamTraits template
  // instantiation.
};

}  // namespace layers
}  // namespace mozilla

#endif  // mozilla_gfx_layers_LayerAttributes_h