cc/scrollbar_geometry_fixed_thumb.cc

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/scrollbar_geometry_fixed_thumb.h"
   6
   7 #include <cmath>
   8
   9 #include "third_party/WebKit/Source/Platform/chromium/public/WebRect.h"
  10 #include "third_party/WebKit/Source/Platform/chromium/public/WebScrollbar.h"
  11
  12 using WebKit::WebRect;
  13 using WebKit::WebScrollbar;
  14 using WebKit::WebScrollbarThemeGeometry;
  15
  16 namespace cc {
  17
  18 scoped_ptr<ScrollbarGeometryFixedThumb> ScrollbarGeometryFixedThumb::create(scoped_ptr<WebScrollbarThemeGeometry> geometry)
  19 {
  20     return make_scoped_ptr(new ScrollbarGeometryFixedThumb(geometry.Pass()));
  21 }
  22
  23 ScrollbarGeometryFixedThumb::~ScrollbarGeometryFixedThumb()
  24 {
  25 }
  26
  27 WebScrollbarThemeGeometry* ScrollbarGeometryFixedThumb::clone() const
  28 {
  29     ScrollbarGeometryFixedThumb* geometry = new ScrollbarGeometryFixedThumb(make_scoped_ptr(ScrollbarGeometryStub::clone()));
  30     geometry->m_thumbSize = m_thumbSize;
  31     return geometry;
  32 }
  33
  34 int ScrollbarGeometryFixedThumb::thumbLength(WebScrollbar* scrollbar)
  35 {
  36     if (scrollbar->orientation() == WebScrollbar::Horizontal)
  37         return m_thumbSize.width();
  38     return m_thumbSize.height();
  39 }
  40
  41 int ScrollbarGeometryFixedThumb::thumbPosition(WebScrollbar* scrollbar)
  42 {
  43     if (scrollbar->enabled()) {
  44         float size = scrollbar->maximum();
  45         if (!size)
  46             return 1;
  47         int value = std::min(std::max(0, scrollbar->value()), scrollbar->maximum());
  48         float pos = (trackLength(scrollbar) - thumbLength(scrollbar)) * value / size;
  49         return static_cast<int>(floorf((pos < 1 && pos > 0) ? 1 : pos));
  50     }
  51     return 0;
  52 }
  53 void ScrollbarGeometryFixedThumb::splitTrack(WebScrollbar* scrollbar, const WebRect& unconstrainedTrackRect, WebRect& beforeThumbRect, WebRect& thumbRect, WebRect& afterThumbRect)
  54 {
  55     // This is a reimplementation of ScrollbarThemeComposite::splitTrack.
  56     // Because the WebScrollbarThemeGeometry functions call down to native
  57     // ScrollbarThemeComposite code which uses ScrollbarThemeComposite virtual
  58     // helpers, there's no way to override a helper like thumbLength from
  59     // the WebScrollbarThemeGeometry level. So, these three functions
  60     // (splitTrack, thumbPosition, thumbLength) are copied here so that the
  61     // WebScrollbarThemeGeometry helper functions are used instead and
  62     // a fixed size thumbLength can be used.
  63
  64     WebRect trackRect = constrainTrackRectToTrackPieces(scrollbar, unconstrainedTrackRect);
  65     int thickness = scrollbar->orientation() == WebScrollbar::Horizontal ? scrollbar->size().height : scrollbar->size().width;
  66     int thumbPos = thumbPosition(scrollbar);
  67     if (scrollbar->orientation() == WebScrollbar::Horizontal) {
  68         thumbRect = WebRect(trackRect.x + thumbPos, trackRect.y + (trackRect.height - thickness) / 2, thumbLength(scrollbar), thickness);
  69         beforeThumbRect = WebRect(trackRect.x, trackRect.y, thumbPos + thumbRect.width / 2, trackRect.height);
  70         afterThumbRect = WebRect(trackRect.x + beforeThumbRect.width, trackRect.y, trackRect.x + trackRect.width - beforeThumbRect.x - beforeThumbRect.width, trackRect.height);
  71     } else {
  72         thumbRect = WebRect(trackRect.x + (trackRect.width - thickness) / 2, trackRect.y + thumbPos, thickness, thumbLength(scrollbar));
  73         beforeThumbRect = WebRect(trackRect.x, trackRect.y, trackRect.width, thumbPos + thumbRect.height / 2);
  74         afterThumbRect = WebRect(trackRect.x, trackRect.y + beforeThumbRect.height, trackRect.width, trackRect.y + trackRect.height - beforeThumbRect.y - beforeThumbRect.height);
  75     }
  76 }
  77
  78 ScrollbarGeometryFixedThumb::ScrollbarGeometryFixedThumb(scoped_ptr<WebScrollbarThemeGeometry> geometry)
  79     : ScrollbarGeometryStub(geometry.Pass())
  80 {
  81 }
  82
  83 }  // namespace cc