gfx/layers/ScrollbarData.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_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