widget/ScrollbarDrawingAndroid.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 "ScrollbarDrawingAndroid.h"
   7
   8 #include "nsIFrame.h"
   9 #include "nsNativeTheme.h"
  10 #include "mozilla/StaticPrefs_widget.h"
  11
  12 using namespace mozilla;
  13 using namespace mozilla::widget;
  14
  15 LayoutDeviceIntSize ScrollbarDrawingAndroid::GetMinimumWidgetSize(
  16     nsPresContext* aPresContext, StyleAppearance aAppearance,
  17     nsIFrame* aFrame) {
  18   MOZ_ASSERT(nsNativeTheme::IsWidgetScrollbarPart(aAppearance));
  19
  20   auto sizes =
  21       GetScrollbarSizes(aPresContext, StyleScrollbarWidth::Auto, Overlay::Yes);
  22   MOZ_ASSERT(sizes.mHorizontal == sizes.mVertical);
  23
  24   return LayoutDeviceIntSize{sizes.mHorizontal, sizes.mVertical};
  25 }
  26
  27 auto ScrollbarDrawingAndroid::GetScrollbarSizes(nsPresContext* aPresContext,
  28                                                 StyleScrollbarWidth aWidth,
  29                                                 Overlay aOverlay)
  30     -> ScrollbarSizes {
  31   // We force auto-width scrollbars because scrollbars on android are already
  32   // thin enough.
  33   return ScrollbarDrawing::GetScrollbarSizes(
  34       aPresContext, StyleScrollbarWidth::Auto, aOverlay);
  35 }
  36
  37 template <typename PaintBackendData>
  38 void ScrollbarDrawingAndroid::DoPaintScrollbarThumb(
  39     PaintBackendData& aPaintData, const LayoutDeviceRect& aRect,
  40     ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,
  41     const ElementState& aElementState, const DocumentState& aDocumentState,
  42     const Colors& aColors, const DPIRatio& aDpiRatio) {
  43   // TODO(emilio): Maybe do like macOS and draw a stroke?
  44   const auto color = ComputeScrollbarThumbColor(aFrame, aStyle, aElementState,
  45                                                 aDocumentState, aColors);
  46   const bool horizontal = aScrollbarKind == ScrollbarKind::Horizontal;
  47
  48   // Draw the thumb rect centered in the scrollbar.
  49   LayoutDeviceRect thumbRect(aRect);
  50   if (horizontal) {
  51     thumbRect.height *= 0.5f;
  52     thumbRect.y += thumbRect.height * 0.5f;
  53   } else {
  54     thumbRect.width *= 0.5f;
  55     thumbRect.x += thumbRect.width * 0.5f;
  56   }
  57
  58   const LayoutDeviceCoord radius =
  59       (horizontal ? thumbRect.height : thumbRect.width) / 2.0f;
  60   ThemeDrawing::PaintRoundedRectWithRadius(aPaintData, thumbRect, color,
  61                                            sRGBColor::White(0.0f), 0.0f,
  62                                            radius / aDpiRatio, aDpiRatio);
  63 }
  64
  65 bool ScrollbarDrawingAndroid::PaintScrollbarThumb(
  66     DrawTarget& aDt, const LayoutDeviceRect& aRect,
  67     ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,
  68     const ElementState& aElementState, const DocumentState& aDocumentState,
  69     const Colors& aColors, const DPIRatio& aDpiRatio) {
  70   DoPaintScrollbarThumb(aDt, aRect, aScrollbarKind, aFrame, aStyle,
  71                         aElementState, aDocumentState, aColors, aDpiRatio);
  72   return true;
  73 }
  74
  75 bool ScrollbarDrawingAndroid::PaintScrollbarThumb(
  76     WebRenderBackendData& aWrData, const LayoutDeviceRect& aRect,
  77     ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,
  78     const ElementState& aElementState, const DocumentState& aDocumentState,
  79     const Colors& aColors, const DPIRatio& aDpiRatio) {
  80   DoPaintScrollbarThumb(aWrData, aRect, aScrollbarKind, aFrame, aStyle,
  81                         aElementState, aDocumentState, aColors, aDpiRatio);
  82   return true;
  83 }
  84
  85 void ScrollbarDrawingAndroid::RecomputeScrollbarParams() {
  86   uint32_t defaultSize = 6;
  87   uint32_t overrideSize =
  88       StaticPrefs::widget_non_native_theme_scrollbar_size_override();
  89   if (overrideSize > 0) {
  90     defaultSize = overrideSize;
  91   }
  92   mHorizontalScrollbarHeight = mVerticalScrollbarWidth = defaultSize;
  93 }