widget/ScrollbarDrawingWin.cpp

   1 /* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "ScrollbarDrawingWin.h"
   7
   8 #include "mozilla/gfx/Helpers.h"
   9 #include "mozilla/Maybe.h"
  10 #include "mozilla/StaticPrefs_widget.h"
  11 #include "nsLayoutUtils.h"
  12 #include "Theme.h"
  13 #include "nsNativeTheme.h"
  14
  15 namespace mozilla::widget {
  16
  17 LayoutDeviceIntSize ScrollbarDrawingWin::GetMinimumWidgetSize(
  18     nsPresContext* aPresContext, StyleAppearance aAppearance,
  19     nsIFrame* aFrame) {
  20   MOZ_ASSERT(nsNativeTheme::IsWidgetScrollbarPart(aAppearance));
  21
  22   switch (aAppearance) {
  23     case StyleAppearance::ScrollbarbuttonUp:
  24     case StyleAppearance::ScrollbarbuttonDown:
  25     case StyleAppearance::ScrollbarbuttonLeft:
  26     case StyleAppearance::ScrollbarbuttonRight:
  27       // For scrollbar-width:thin, we don't display the buttons.
  28       if (IsScrollbarWidthThin(aFrame)) {
  29         return LayoutDeviceIntSize{};
  30       }
  31       [[fallthrough]];
  32     case StyleAppearance::ScrollbarVertical:
  33     case StyleAppearance::ScrollbarHorizontal:
  34     case StyleAppearance::ScrollbarthumbVertical:
  35     case StyleAppearance::ScrollbarthumbHorizontal: {
  36       if ((aAppearance == StyleAppearance::ScrollbarHorizontal ||
  37            aAppearance == StyleAppearance::ScrollbarVertical) &&
  38           !aPresContext->UseOverlayScrollbars()) {
  39         return LayoutDeviceIntSize{};
  40       }
  41       // TODO: for short scrollbars it could be nice if the thumb could shrink
  42       // under this size.
  43       auto sizes = GetScrollbarSizes(aPresContext, aFrame);
  44       const bool isHorizontal =
  45           aAppearance == StyleAppearance::ScrollbarHorizontal ||
  46           aAppearance == StyleAppearance::ScrollbarthumbHorizontal ||
  47           aAppearance == StyleAppearance::ScrollbarbuttonLeft ||
  48           aAppearance == StyleAppearance::ScrollbarbuttonRight;
  49       const auto size = isHorizontal ? sizes.mHorizontal : sizes.mVertical;
  50       return LayoutDeviceIntSize{size, size};
  51     }
  52     default:
  53       return LayoutDeviceIntSize{};
  54   }
  55 }
  56
  57 // Returns the style for custom scrollbar if the scrollbar part frame should
  58 // use the custom drawing path, nullptr otherwise.
  59 const ComputedStyle* GetCustomScrollbarStyle(nsIFrame* aFrame) {
  60   const ComputedStyle* style = nsLayoutUtils::StyleForScrollbar(aFrame);
  61   if (style->StyleUI()->HasCustomScrollbars() ||
  62       ScrollbarDrawing::IsScrollbarWidthThin(*style)) {
  63     return style;
  64   }
  65   bool useDarkScrollbar = !StaticPrefs::widget_disable_dark_scrollbar() &&
  66                           nsNativeTheme::IsDarkBackgroundForScrollbar(aFrame);
  67   if (useDarkScrollbar) {
  68     return style;
  69   }
  70   return nullptr;
  71 }
  72
  73 Maybe<nsITheme::Transparency> ScrollbarDrawingWin::GetScrollbarPartTransparency(
  74     nsIFrame* aFrame, StyleAppearance aAppearance) {
  75   if (nsNativeTheme::IsWidgetScrollbarPart(aAppearance)) {
  76     if (const ComputedStyle* style = GetCustomScrollbarStyle(aFrame)) {
  77       auto* ui = style->StyleUI();
  78       if (ui->mScrollbarColor.IsAuto() ||
  79           ui->mScrollbarColor.AsColors().track.MaybeTransparent()) {
  80         return Some(nsITheme::eTransparent);
  81       }
  82       // These widgets may be thinner than the track, so we need to return
  83       // transparent for them to make the track visible.
  84       switch (aAppearance) {
  85         case StyleAppearance::ScrollbarthumbHorizontal:
  86         case StyleAppearance::ScrollbarthumbVertical:
  87         case StyleAppearance::ScrollbarbuttonUp:
  88         case StyleAppearance::ScrollbarbuttonDown:
  89         case StyleAppearance::ScrollbarbuttonLeft:
  90         case StyleAppearance::ScrollbarbuttonRight:
  91           return Some(nsITheme::eTransparent);
  92         default:
  93           break;
  94       }
  95     }
  96     if (aFrame->PresContext()->UseOverlayScrollbars()) {
  97       return Some(nsITheme::eTransparent);
  98     }
  99   }
 100
 101   switch (aAppearance) {
 102     case StyleAppearance::ScrollbarHorizontal:
 103     case StyleAppearance::ScrollbarVertical:
 104     case StyleAppearance::Scrollcorner:
 105     case StyleAppearance::Statusbar:
 106       // Knowing that scrollbars and statusbars are opaque improves
 107       // performance, because we create layers for them. This better be
 108       // true across all Windows themes! If it's not true, we should
 109       // paint an opaque background for them to make it true!
 110       // TODO(emilio): Unclear how much this optimization matters in practice
 111       // now we're in a WR-only world.
 112       return Some(nsITheme::eOpaque);
 113     default:
 114       break;
 115   }
 116
 117   return Nothing();
 118 }
 119
 120 template <typename PaintBackendData>
 121 bool ScrollbarDrawingWin::DoPaintScrollbarThumb(
 122     PaintBackendData& aPaintData, const LayoutDeviceRect& aRect,
 123     ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,
 124     const ElementState& aElementState, const DocumentState& aDocumentState,
 125     const Colors& aColors, const DPIRatio& aDpiRatio) {
 126   sRGBColor thumbColor = ComputeScrollbarThumbColor(
 127       aFrame, aStyle, aElementState, aDocumentState, aColors);
 128   ThemeDrawing::FillRect(aPaintData, aRect, thumbColor);
 129   return true;
 130 }
 131
 132 bool ScrollbarDrawingWin::PaintScrollbarThumb(
 133     DrawTarget& aDrawTarget, const LayoutDeviceRect& aRect,
 134     ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,
 135     const ElementState& aElementState, const DocumentState& aDocumentState,
 136     const Colors& aColors, const DPIRatio& aDpiRatio) {
 137   return DoPaintScrollbarThumb(aDrawTarget, aRect, aScrollbarKind, aFrame,
 138                                aStyle, aElementState, aDocumentState, aColors,
 139                                aDpiRatio);
 140 }
 141
 142 bool ScrollbarDrawingWin::PaintScrollbarThumb(
 143     WebRenderBackendData& aWrData, const LayoutDeviceRect& aRect,
 144     ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,
 145     const ElementState& aElementState, const DocumentState& aDocumentState,
 146     const Colors& aColors, const DPIRatio& aDpiRatio) {
 147   return DoPaintScrollbarThumb(aWrData, aRect, aScrollbarKind, aFrame, aStyle,
 148                                aElementState, aDocumentState, aColors,
 149                                aDpiRatio);
 150 }
 151
 152 void ScrollbarDrawingWin::RecomputeScrollbarParams() {
 153   uint32_t defaultSize = kDefaultWinScrollbarSize;
 154   uint32_t overrideSize =
 155       StaticPrefs::widget_non_native_theme_scrollbar_size_override();
 156   if (overrideSize > 0) {
 157     defaultSize = overrideSize;
 158   }
 159   mHorizontalScrollbarHeight = mVerticalScrollbarWidth = defaultSize;
 160
 161   if (StaticPrefs::widget_non_native_theme_win_scrollbar_use_system_size()) {
 162     mHorizontalScrollbarHeight = LookAndFeel::GetInt(
 163         LookAndFeel::IntID::SystemHorizontalScrollbarHeight, defaultSize);
 164     mVerticalScrollbarWidth = LookAndFeel::GetInt(
 165         LookAndFeel::IntID::SystemVerticalScrollbarWidth, defaultSize);
 166   }
 167 }
 168
 169 }  // namespace mozilla::widget