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ScrollbarData.h (4672B)

      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_gfx_layers_ScrollbarData_h
      8 #define mozilla_gfx_layers_ScrollbarData_h
      9 
     10 #include "FrameMetrics.h"
     11 #include "mozilla/Maybe.h"
     12 #include "mozilla/gfx/Types.h"
     13 #include "mozilla/layers/LayersTypes.h"
     14 #include "mozilla/layers/ScrollableLayerGuid.h"
     15 
     16 namespace IPC {
     17 template <typename T>
     18 struct ParamTraits;
     19 }  // namespace IPC
     20 
     21 namespace mozilla {
     22 namespace layers {
     23 
     24 // clang-format off
     25 MOZ_DEFINE_ENUM_CLASS_WITH_BASE(ScrollbarLayerType, uint8_t, (
     26  None,
     27  Thumb,
     28  Container
     29 ));
     30 // clang-format on
     31 
     32 /**
     33 *  It stores data for scroll thumb layer or container layers.
     34 */
     35 struct ScrollbarData {
     36 private:
     37  /**
     38   * This constructor is for Thumb layer type.
     39   */
     40  ScrollbarData(ScrollDirection aDirection, float aThumbRatio,
     41                OuterCSSCoord aThumbStart, OuterCSSCoord aThumbLength,
     42                OuterCSSCoord aThumbMinLength, bool aThumbIsAsyncDraggable,
     43                OuterCSSCoord aScrollTrackStart,
     44                OuterCSSCoord aScrollTrackLength, uint64_t aTargetViewId)
     45      : mDirection(Some(aDirection)),
     46        mScrollbarLayerType(ScrollbarLayerType::Thumb),
     47        mThumbRatio(aThumbRatio),
     48        mThumbStart(aThumbStart),
     49        mThumbLength(aThumbLength),
     50        mThumbMinLength(aThumbMinLength),
     51        mThumbIsAsyncDraggable(aThumbIsAsyncDraggable),
     52        mScrollTrackStart(aScrollTrackStart),
     53        mScrollTrackLength(aScrollTrackLength),
     54        mTargetViewId(aTargetViewId) {}
     55 
     56  /**
     57   * This constructor is for Container layer type.
     58   */
     59  ScrollbarData(const Maybe<ScrollDirection>& aDirection,
     60                uint64_t aTargetViewId)
     61      : mDirection(aDirection),
     62        mScrollbarLayerType(ScrollbarLayerType::Container),
     63        mTargetViewId(aTargetViewId) {}
     64 
     65 public:
     66  ScrollbarData() = default;
     67 
     68  static ScrollbarData CreateForThumb(
     69      ScrollDirection aDirection, float aThumbRatio, OuterCSSCoord aThumbStart,
     70      OuterCSSCoord aThumbLength, OuterCSSCoord aThumbMinLength,
     71      bool aThumbIsAsyncDraggable, OuterCSSCoord aScrollTrackStart,
     72      OuterCSSCoord aScrollTrackLength, uint64_t aTargetViewId) {
     73    return ScrollbarData(aDirection, aThumbRatio, aThumbStart, aThumbLength,
     74                         aThumbMinLength, aThumbIsAsyncDraggable,
     75                         aScrollTrackStart, aScrollTrackLength, aTargetViewId);
     76  }
     77 
     78  static ScrollbarData CreateForScrollbarContainer(
     79      const Maybe<ScrollDirection>& aDirection, uint64_t aTargetViewId) {
     80    return ScrollbarData(aDirection, aTargetViewId);
     81  }
     82 
     83  /**
     84   * The mDirection contains a direction if mScrollbarLayerType is Thumb
     85   * or Container, otherwise it's empty.
     86   */
     87  Maybe<ScrollDirection> mDirection;
     88 
     89  /**
     90   * Indicate what kind of layer this data is for. All possibilities are defined
     91   * in enum ScrollbarLayerType
     92   */
     93  ScrollbarLayerType mScrollbarLayerType = ScrollbarLayerType::None;
     94 
     95  /**
     96   * The scrollbar thumb ratio is the ratio of the thumb position (in the CSS
     97   * pixels of the scrollframe's parent's space) to the scroll position (in the
     98   * CSS pixels of the scrollframe's space).
     99   */
    100  float mThumbRatio = 0.0f;
    101 
    102  OuterCSSCoord mThumbStart;
    103  OuterCSSCoord mThumbLength;
    104  OuterCSSCoord mThumbMinLength;
    105 
    106  /**
    107   * Whether the scrollbar thumb can be dragged asynchronously.
    108   */
    109  bool mThumbIsAsyncDraggable = false;
    110 
    111  OuterCSSCoord mScrollTrackStart;
    112  OuterCSSCoord mScrollTrackLength;
    113  uint64_t mTargetViewId = ScrollableLayerGuid::NULL_SCROLL_ID;
    114 
    115  bool operator==(const ScrollbarData& aOther) const {
    116    return mDirection == aOther.mDirection &&
    117           mScrollbarLayerType == aOther.mScrollbarLayerType &&
    118           mThumbRatio == aOther.mThumbRatio &&
    119           mThumbStart == aOther.mThumbStart &&
    120           mThumbLength == aOther.mThumbLength &&
    121           mThumbMinLength == aOther.mThumbMinLength &&
    122           mThumbIsAsyncDraggable == aOther.mThumbIsAsyncDraggable &&
    123           mScrollTrackStart == aOther.mScrollTrackStart &&
    124           mScrollTrackLength == aOther.mScrollTrackLength &&
    125           mTargetViewId == aOther.mTargetViewId;
    126  }
    127  bool operator!=(const ScrollbarData& aOther) const {
    128    return !(*this == aOther);
    129  }
    130 
    131  bool IsThumb() const {
    132    return mScrollbarLayerType == ScrollbarLayerType::Thumb;
    133  }
    134 };
    135 
    136 }  // namespace layers
    137 }  // namespace mozilla
    138 
    139 #endif  // mozilla_gfx_layers_ScrollbarData_h