ScrollbarDrawingAndroid.cpp

Enable keyboard shortcuts

/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* 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/. */

#include "ScrollbarDrawingAndroid.h"

#include "nsIFrame.h"

#include "nsNativeTheme.h"

#include "mozilla/StaticPrefs_widget.h"

using namespace mozilla;

using namespace mozilla::widget;

LayoutDeviceIntSize ScrollbarDrawingAndroid::GetMinimumWidgetSize(

    nsPresContext* aPresContext, StyleAppearance aAppearance,

    nsIFrame* aFrame) {

  MOZ_ASSERT(nsNativeTheme::IsWidgetScrollbarPart(aAppearance));

  auto size =

      GetScrollbarSize(aPresContext, StyleScrollbarWidth::Auto, Overlay::Yes);

  return LayoutDeviceIntSize{size, size};

template <typename PaintBackendData>

void ScrollbarDrawingAndroid::DoPaintScrollbarThumb(

    PaintBackendData& aPaintData, const LayoutDeviceRect& aRect,

    ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,

    const ElementState& aElementState, const DocumentState& aDocumentState,

    const Colors& aColors, const DPIRatio& aDpiRatio) {

  // TODO(emilio): Maybe do like macOS and draw a stroke?

  const auto color = ComputeScrollbarThumbColor(aFrame, aStyle, aElementState,

                                                aDocumentState, aColors);

  const bool horizontal = aScrollbarKind == ScrollbarKind::Horizontal;

  // Draw the thumb rect centered in the scrollbar.

  LayoutDeviceRect thumbRect(aRect);

  if (horizontal) {

    thumbRect.height *= 0.5f;

    thumbRect.y += thumbRect.height * 0.5f;

  } else {

    thumbRect.width *= 0.5f;

    thumbRect.x += thumbRect.width * 0.5f;

  const LayoutDeviceCoord radius =

      (horizontal ? thumbRect.height : thumbRect.width) / 2.0f;

  ThemeDrawing::PaintRoundedRectWithRadius(aPaintData, thumbRect, color,

                                           sRGBColor::White(0.0f), 0.0f,

                                           radius / aDpiRatio, aDpiRatio);

bool ScrollbarDrawingAndroid::PaintScrollbarThumb(

    DrawTarget& aDt, const LayoutDeviceRect& aRect,

    ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,

    const ElementState& aElementState, const DocumentState& aDocumentState,

    const Colors& aColors, const DPIRatio& aDpiRatio) {

  DoPaintScrollbarThumb(aDt, aRect, aScrollbarKind, aFrame, aStyle,

                        aElementState, aDocumentState, aColors, aDpiRatio);

  return true;

bool ScrollbarDrawingAndroid::PaintScrollbarThumb(

    WebRenderBackendData& aWrData, const LayoutDeviceRect& aRect,

    ScrollbarKind aScrollbarKind, nsIFrame* aFrame, const ComputedStyle& aStyle,

    const ElementState& aElementState, const DocumentState& aDocumentState,

    const Colors& aColors, const DPIRatio& aDpiRatio) {

  DoPaintScrollbarThumb(aWrData, aRect, aScrollbarKind, aFrame, aStyle,

                        aElementState, aDocumentState, aColors, aDpiRatio);

  return true;

void ScrollbarDrawingAndroid::RecomputeScrollbarParams() {

  uint32_t defaultSize = 6;

  uint32_t overrideSize =

      StaticPrefs::widget_non_native_theme_scrollbar_size_override();

  if (overrideSize > 0) {

    defaultSize = overrideSize;

  ConfigureScrollbarSize(defaultSize);

  // We make thin scrollbars as wide as auto ones because auto scrollbars on

  // android are already thin enough.

  ConfigureScrollbarSize(StyleScrollbarWidth::Thin, Overlay::Yes, defaultSize);

  ConfigureScrollbarSize(StyleScrollbarWidth::Thin, Overlay::No, defaultSize);