chromium/src/third_party/blink/renderer/core/scroll/scrollbar_theme_overlay.cc

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "third_party/blink/renderer/core/scroll/scrollbar_theme_overlay.h"

#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/public/platform/web_theme_engine.h"
#include "third_party/blink/renderer/core/scroll/scrollbar.h"
#include "third_party/blink/renderer/platform/graphics/graphics_context.h"
#include "third_party/blink/renderer/platform/graphics/paint/drawing_recorder.h"
#include "third_party/blink/renderer/platform/transforms/transformation_matrix.h"
#include "third_party/blink/renderer/platform/wtf/math_extras.h"

#include <algorithm>

namespace blink {

ScrollbarThemeOverlay& ScrollbarThemeOverlay::GetInstance() {
  DEFINE_STATIC_LOCAL(
      ScrollbarThemeOverlay, theme,
      (Platform::Current()
           ->ThemeEngine()
           ->GetSize(WebThemeEngine::kPartScrollbarVerticalThumb)
           .width(),
       0));
  return theme;
}

ScrollbarThemeOverlay::ScrollbarThemeOverlay(int thumb_thickness_dip,
                                             int scrollbar_margin_dip)
    : thumb_thickness_dip_(thumb_thickness_dip),
      scrollbar_margin_dip_(scrollbar_margin_dip) {}

bool ScrollbarThemeOverlay::ShouldRepaintAllPartsOnInvalidation() const {
  return false;
}

ScrollbarPart ScrollbarThemeOverlay::PartsToInvalidateOnThumbPositionChange(
    const Scrollbar&,
    float old_position,
    float new_position) const {
  return kNoPart;
}

int ScrollbarThemeOverlay::ScrollbarThickness(float scale_from_dip) {
  return ThumbThickness(scale_from_dip) + ScrollbarMargin(scale_from_dip);
}

int ScrollbarThemeOverlay::ScrollbarMargin(float scale_from_dip) const {
  return scrollbar_margin_dip_ * scale_from_dip;
}

bool ScrollbarThemeOverlay::UsesOverlayScrollbars() const {
  return true;
}

base::TimeDelta ScrollbarThemeOverlay::OverlayScrollbarFadeOutDelay() const {
  WebThemeEngine::ScrollbarStyle style;
  DCHECK(Platform::Current()->ThemeEngine());
  Platform::Current()->ThemeEngine()->GetOverlayScrollbarStyle(&style);
  return style.fade_out_delay;
}

base::TimeDelta ScrollbarThemeOverlay::OverlayScrollbarFadeOutDuration() const {
  WebThemeEngine::ScrollbarStyle style;
  DCHECK(Platform::Current()->ThemeEngine());
  Platform::Current()->ThemeEngine()->GetOverlayScrollbarStyle(&style);
  return style.fade_out_duration;
}

int ScrollbarThemeOverlay::ThumbLength(const Scrollbar& scrollbar) {
  int track_len = TrackLength(scrollbar);

  if (!scrollbar.TotalSize())
    return track_len;

  float proportion =
      static_cast<float>(scrollbar.VisibleSize()) / scrollbar.TotalSize();
  int length = round(proportion * track_len);
  int min_len = std::min(MinimumThumbLength(scrollbar), track_len);
  length = clampTo(length, min_len, track_len);
  return length;
}

bool ScrollbarThemeOverlay::HasThumb(const Scrollbar& scrollbar) {
  return true;
}

IntRect ScrollbarThemeOverlay::BackButtonRect(const Scrollbar&) {
  return IntRect();
}

IntRect ScrollbarThemeOverlay::ForwardButtonRect(const Scrollbar&) {
  return IntRect();
}

IntRect ScrollbarThemeOverlay::TrackRect(const Scrollbar& scrollbar) {
  IntRect rect = scrollbar.FrameRect();
  if (scrollbar.Orientation() == kHorizontalScrollbar)
    rect.InflateX(-ScrollbarMargin(scrollbar.ScaleFromDIP()));
  else
    rect.InflateY(-ScrollbarMargin(scrollbar.ScaleFromDIP()));
  return rect;
}

IntRect ScrollbarThemeOverlay::ThumbRect(const Scrollbar& scrollbar) {
  IntRect rect = ScrollbarTheme::ThumbRect(scrollbar);
  if (scrollbar.Orientation() == kHorizontalScrollbar) {
    rect.SetHeight(ThumbThickness(scrollbar.ScaleFromDIP()));
  } else {
    if (scrollbar.IsLeftSideVerticalScrollbar())
      rect.Move(ScrollbarMargin(scrollbar.ScaleFromDIP()), 0);
    rect.SetWidth(ThumbThickness(scrollbar.ScaleFromDIP()));
  }
  return rect;
}

void ScrollbarThemeOverlay::PaintThumb(GraphicsContext& context,
                                       const Scrollbar& scrollbar,
                                       const IntRect& rect) {
  if (DrawingRecorder::UseCachedDrawingIfPossible(context, scrollbar,
                                                  DisplayItem::kScrollbarThumb))
    return;

  DrawingRecorder recorder(context, scrollbar, DisplayItem::kScrollbarThumb,
                           rect);

  WebThemeEngine::State state = WebThemeEngine::kStateNormal;

  if (!scrollbar.Enabled())
    state = WebThemeEngine::kStateDisabled;
  else if (scrollbar.PressedPart() == kThumbPart)
    state = WebThemeEngine::kStatePressed;
  else if (scrollbar.HoveredPart() == kThumbPart)
    state = WebThemeEngine::kStateHover;

  cc::PaintCanvas* canvas = context.Canvas();

  WebThemeEngine::Part part = WebThemeEngine::kPartScrollbarHorizontalThumb;
  if (scrollbar.Orientation() == kVerticalScrollbar)
    part = WebThemeEngine::kPartScrollbarVerticalThumb;

  blink::WebThemeEngine::ExtraParams params;
  params.scrollbar_thumb.scrollbar_theme =
      static_cast<WebScrollbarOverlayColorTheme>(
          scrollbar.GetScrollbarOverlayColorTheme());

  // Horizontally flip the canvas if it is left vertical scrollbar.
  if (scrollbar.IsLeftSideVerticalScrollbar()) {
    canvas->save();
    canvas->translate(rect.Width(), 0);
    canvas->scale(-1, 1);
  }

  Platform::Current()->ThemeEngine()->Paint(canvas, part, state,
                                            gfx::Rect(rect), &params,
                                            scrollbar.UsedColorScheme());

  if (scrollbar.IsLeftSideVerticalScrollbar())
    canvas->restore();
}

ScrollbarPart ScrollbarThemeOverlay::HitTest(const Scrollbar& scrollbar,
                                             const IntPoint& position) {
  ScrollbarPart part = ScrollbarTheme::HitTest(scrollbar, position);
  if (part != kThumbPart)
    return kNoPart;

  return kThumbPart;
}

bool ScrollbarThemeOverlay::UsesNinePatchThumbResource() const {
  DCHECK(Platform::Current()->ThemeEngine());
  // Thumb orientation doesn't matter here.
  return Platform::Current()->ThemeEngine()->SupportsNinePatch(
      WebThemeEngine::kPartScrollbarVerticalThumb);
}

IntSize ScrollbarThemeOverlay::NinePatchThumbCanvasSize(
    const Scrollbar& scrollbar) const {
  DCHECK(UsesNinePatchThumbResource());

  WebThemeEngine::Part part =
      scrollbar.Orientation() == kVerticalScrollbar
          ? WebThemeEngine::kPartScrollbarVerticalThumb
          : WebThemeEngine::kPartScrollbarHorizontalThumb;

  DCHECK(Platform::Current()->ThemeEngine());
  return IntSize(Platform::Current()->ThemeEngine()->NinePatchCanvasSize(part));
}

IntRect ScrollbarThemeOverlay::NinePatchThumbAperture(
    const Scrollbar& scrollbar) const {
  DCHECK(UsesNinePatchThumbResource());

  WebThemeEngine::Part part = WebThemeEngine::kPartScrollbarHorizontalThumb;
  if (scrollbar.Orientation() == kVerticalScrollbar)
    part = WebThemeEngine::kPartScrollbarVerticalThumb;

  DCHECK(Platform::Current()->ThemeEngine());
  return IntRect(Platform::Current()->ThemeEngine()->NinePatchAperture(part));
}

int ScrollbarThemeOverlay::MinimumThumbLength(const Scrollbar& scrollbar) {
  if (scrollbar.Orientation() == kVerticalScrollbar) {
    return Platform::Current()
        ->ThemeEngine()
        ->GetSize(WebThemeEngine::kPartScrollbarVerticalThumb)
        .height();
  }

  return Platform::Current()
      ->ThemeEngine()
      ->GetSize(WebThemeEngine::kPartScrollbarHorizontalThumb)
      .width();
}

}  // namespace blink