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 #include <public/WebRect.h>
   9 #include <public/WebScrollbar.h>
  10
  11 using WebKit::WebRect;
  12 using WebKit::WebScrollbar;
  13 using WebKit::WebScrollbarThemeGeometry;
  14
  15 namespace cc {
  16
  17 scoped_ptr<ScrollbarGeometryFixedThumb> ScrollbarGeometryFixedThumb::create(scoped_ptr<WebScrollbarThemeGeometry> geometry)
  18 {
  19     return make_scoped_ptr(new ScrollbarGeometryFixedThumb(geometry.Pass()));
  20 }
  21
  22 ScrollbarGeometryFixedThumb::~ScrollbarGeometryFixedThumb()
  23 {
  24 }
  25
  26 void ScrollbarGeometryFixedThumb::update(WebScrollbar* scrollbar)
  27 {
  28     int length = ScrollbarGeometryStub::thumbLength(scrollbar);
  29
  30     if (scrollbar->orientation() == WebScrollbar::Horizontal)
  31         m_thumbSize = gfx::Size(length, scrollbar->size().height);
  32     else
  33         m_thumbSize = gfx::Size(scrollbar->size().width, length);
  34 }
  35
  36 WebScrollbarThemeGeometry* ScrollbarGeometryFixedThumb::clone() const
  37 {
  38     ScrollbarGeometryFixedThumb* geometry = new ScrollbarGeometryFixedThumb(make_scoped_ptr(ScrollbarGeometryStub::clone()));
  39     geometry->m_thumbSize = m_thumbSize;
  40     return geometry;
  41 }
  42
  43 int ScrollbarGeometryFixedThumb::thumbLength(WebScrollbar* scrollbar)
  44 {
  45     if (scrollbar->orientation() == WebScrollbar::Horizontal)
  46         return m_thumbSize.width();
  47     return m_thumbSize.height();
  48 }
  49
  50 int ScrollbarGeometryFixedThumb::thumbPosition(WebScrollbar* scrollbar)
  51 {
  52     if (scrollbar->enabled()) {
  53         float size = scrollbar->maximum();
  54         if (!size)
  55             return 1;
  56         int value = std::min(std::max(0, scrollbar->value()), scrollbar->maximum());
  57         float pos = (trackLength(scrollbar) - thumbLength(scrollbar)) * value / size;
  58         return static_cast<int>(floorf((pos < 1 && pos > 0) ? 1 : pos));
  59     }
  60     return 0;
  61 }
  62 void ScrollbarGeometryFixedThumb::splitTrack(WebScrollbar* scrollbar, const WebRect& unconstrainedTrackRect, WebRect& beforeThumbRect, WebRect& thumbRect, WebRect& afterThumbRect)
  63 {
  64     // This is a reimplementation of ScrollbarThemeComposite::splitTrack.
  65     // Because the WebScrollbarThemeGeometry functions call down to native
  66     // ScrollbarThemeComposite code which uses ScrollbarThemeComposite virtual
  67     // helpers, there's no way to override a helper like thumbLength from
  68     // the WebScrollbarThemeGeometry level. So, these three functions
  69     // (splitTrack, thumbPosition, thumbLength) are copied here so that the
  70     // WebScrollbarThemeGeometry helper functions are used instead and
  71     // a fixed size thumbLength can be used.
  72
  73     WebRect trackRect = constrainTrackRectToTrackPieces(scrollbar, unconstrainedTrackRect);
  74     int thickness = scrollbar->orientation() == WebScrollbar::Horizontal ? scrollbar->size().height : scrollbar->size().width;
  75     int thumbPos = thumbPosition(scrollbar);
  76     if (scrollbar->orientation() == WebScrollbar::Horizontal) {
  77         thumbRect = WebRect(trackRect.x + thumbPos, trackRect.y + (trackRect.height - thickness) / 2, thumbLength(scrollbar), thickness);
  78         beforeThumbRect = WebRect(trackRect.x, trackRect.y, thumbPos + thumbRect.width / 2, trackRect.height);
  79         afterThumbRect = WebRect(trackRect.x + beforeThumbRect.width, trackRect.y, trackRect.x + trackRect.width - beforeThumbRect.x - beforeThumbRect.width, trackRect.height);
  80     } else {
  81         thumbRect = WebRect(trackRect.x + (trackRect.width - thickness) / 2, trackRect.y + thumbPos, thickness, thumbLength(scrollbar));
  82         beforeThumbRect = WebRect(trackRect.x, trackRect.y, trackRect.width, thumbPos + thumbRect.height / 2);
  83         afterThumbRect = WebRect(trackRect.x, trackRect.y + beforeThumbRect.height, trackRect.width, trackRect.y + trackRect.height - beforeThumbRect.y - beforeThumbRect.height);
  84     }
  85 }
  86
  87 ScrollbarGeometryFixedThumb::ScrollbarGeometryFixedThumb(scoped_ptr<WebScrollbarThemeGeometry> geometry)
  88     : ScrollbarGeometryStub(geometry.Pass())
  89 {
  90 }
  91
  92 }  // namespace cc