third_party/WebKit/Source/core/layout/LayoutScrollbarTheme.cpp

/*
 * Copyright (C) 2008 Apple Inc. All Rights Reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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#include "core/layout/LayoutScrollbarTheme.h"

#include "core/layout/LayoutScrollbar.h"
#include "core/paint/ScrollbarPainter.h"
#include "platform/graphics/GraphicsContext.h"
#include "platform/graphics/paint/DrawingRecorder.h"
#include "platform/scroll/Scrollbar.h"
#include "wtf/StdLibExtras.h"

namespace blink {

LayoutScrollbarTheme* LayoutScrollbarTheme::layoutScrollbarTheme() {
  DEFINE_STATIC_LOCAL(LayoutScrollbarTheme, theme, ());
  return &theme;
}

void LayoutScrollbarTheme::buttonSizesAlongTrackAxis(
    const ScrollbarThemeClient& scrollbar,
    int& beforeSize,
    int& afterSize) {
  IntRect firstButton = backButtonRect(scrollbar, BackButtonStartPart);
  IntRect secondButton = forwardButtonRect(scrollbar, ForwardButtonStartPart);
  IntRect thirdButton = backButtonRect(scrollbar, BackButtonEndPart);
  IntRect fourthButton = forwardButtonRect(scrollbar, ForwardButtonEndPart);
  if (scrollbar.orientation() == HorizontalScrollbar) {
    beforeSize = firstButton.width() + secondButton.width();
    afterSize = thirdButton.width() + fourthButton.width();
  } else {
    beforeSize = firstButton.height() + secondButton.height();
    afterSize = thirdButton.height() + fourthButton.height();
  }
}

bool LayoutScrollbarTheme::hasButtons(const ScrollbarThemeClient& scrollbar) {
  int startSize;
  int endSize;
  buttonSizesAlongTrackAxis(scrollbar, startSize, endSize);
  return (startSize + endSize) <=
         (scrollbar.orientation() == HorizontalScrollbar ? scrollbar.width()
                                                         : scrollbar.height());
}

bool LayoutScrollbarTheme::hasThumb(const ScrollbarThemeClient& scrollbar) {
  return trackLength(scrollbar) - thumbLength(scrollbar) >= 0;
}

int LayoutScrollbarTheme::minimumThumbLength(
    const ScrollbarThemeClient& scrollbar) {
  return toLayoutScrollbar(scrollbar).minimumThumbLength();
}

IntRect LayoutScrollbarTheme::backButtonRect(
    const ScrollbarThemeClient& scrollbar,
    ScrollbarPart partType,
    bool) {
  return toLayoutScrollbar(scrollbar).buttonRect(partType);
}

IntRect LayoutScrollbarTheme::forwardButtonRect(
    const ScrollbarThemeClient& scrollbar,
    ScrollbarPart partType,
    bool) {
  return toLayoutScrollbar(scrollbar).buttonRect(partType);
}

IntRect LayoutScrollbarTheme::trackRect(const ScrollbarThemeClient& scrollbar,
                                        bool) {
  if (!hasButtons(scrollbar))
    return scrollbar.frameRect();

  int startLength;
  int endLength;
  buttonSizesAlongTrackAxis(scrollbar, startLength, endLength);

  return toLayoutScrollbar(scrollbar).trackRect(startLength, endLength);
}

IntRect LayoutScrollbarTheme::constrainTrackRectToTrackPieces(
    const ScrollbarThemeClient& scrollbar,
    const IntRect& rect) {
  IntRect backRect = toLayoutScrollbar(scrollbar).trackPieceRectWithMargins(
      BackTrackPart, rect);
  IntRect forwardRect = toLayoutScrollbar(scrollbar).trackPieceRectWithMargins(
      ForwardTrackPart, rect);
  IntRect result = rect;
  if (scrollbar.orientation() == HorizontalScrollbar) {
    result.setX(backRect.x());
    result.setWidth(forwardRect.maxX() - backRect.x());
  } else {
    result.setY(backRect.y());
    result.setHeight(forwardRect.maxY() - backRect.y());
  }
  return result;
}

void LayoutScrollbarTheme::paintScrollCorner(
    GraphicsContext& context,
    const DisplayItemClient& displayItemClient,
    const IntRect& cornerRect) {
  if (DrawingRecorder::useCachedDrawingIfPossible(
          context, displayItemClient, DisplayItem::kScrollbarCorner))
    return;

  DrawingRecorder recorder(context, displayItemClient,
                           DisplayItem::kScrollbarCorner, cornerRect);
  // FIXME: Implement.
  context.fillRect(cornerRect, Color::white);
}

void LayoutScrollbarTheme::paintScrollbarBackground(
    GraphicsContext& context,
    const Scrollbar& scrollbar) {
  ScrollbarPainter(toLayoutScrollbar(scrollbar))
      .paintPart(context, ScrollbarBGPart, scrollbar.frameRect());
}

void LayoutScrollbarTheme::paintTrackBackground(GraphicsContext& context,
                                                const Scrollbar& scrollbar,
                                                const IntRect& rect) {
  ScrollbarPainter(toLayoutScrollbar(scrollbar))
      .paintPart(context, TrackBGPart, rect);
}

void LayoutScrollbarTheme::paintTrackPiece(GraphicsContext& context,
                                           const Scrollbar& scrollbar,
                                           const IntRect& rect,
                                           ScrollbarPart part) {
  ScrollbarPainter(toLayoutScrollbar(scrollbar)).paintPart(context, part, rect);
}

void LayoutScrollbarTheme::paintButton(GraphicsContext& context,
                                       const Scrollbar& scrollbar,
                                       const IntRect& rect,
                                       ScrollbarPart part) {
  ScrollbarPainter(toLayoutScrollbar(scrollbar)).paintPart(context, part, rect);
}

void LayoutScrollbarTheme::paintThumb(GraphicsContext& context,
                                      const Scrollbar& scrollbar,
                                      const IntRect& rect) {
  ScrollbarPainter(toLayoutScrollbar(scrollbar))
      .paintPart(context, ThumbPart, rect);
}

void LayoutScrollbarTheme::paintTickmarks(GraphicsContext& context,
                                          const Scrollbar& scrollbar,
                                          const IntRect& rect) {
  ScrollbarTheme::theme().paintTickmarks(context, scrollbar, rect);
}

}  // namespace blink