cc/CCScrollbarGeometryFixedThumb.cpp

   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 "config.h"
   6
   7 #include "CCScrollbarGeometryFixedThumb.h"
   8
   9 #include <cmath>
  10 #include <public/WebRect.h>
  11 #include <public/WebScrollbar.h>
  12
  13 using WebKit::WebRect;
  14 using WebKit::WebScrollbar;
  15 using WebKit::WebScrollbarThemeGeometry;
  16
  17 namespace cc {
  18
  19 PassOwnPtr<CCScrollbarGeometryFixedThumb> CCScrollbarGeometryFixedThumb::create(PassOwnPtr<WebScrollbarThemeGeometry> geometry)
  20 {
  21     return adoptPtr(new CCScrollbarGeometryFixedThumb(geometry));
  22 }
  23
  24 CCScrollbarGeometryFixedThumb::~CCScrollbarGeometryFixedThumb()
  25 {
  26 }
  27
  28 void CCScrollbarGeometryFixedThumb::update(WebScrollbar* scrollbar)
  29 {
  30     int length = CCScrollbarGeometryStub::thumbLength(scrollbar);
  31
  32     if (scrollbar->orientation() == WebScrollbar::Horizontal)
  33         m_thumbSize = IntSize(length, scrollbar->size().height);
  34     else
  35         m_thumbSize = IntSize(scrollbar->size().width, length);
  36 }
  37
  38 WebScrollbarThemeGeometry* CCScrollbarGeometryFixedThumb::clone() const
  39 {
  40     CCScrollbarGeometryFixedThumb* geometry = new CCScrollbarGeometryFixedThumb(adoptPtr(CCScrollbarGeometryStub::clone()));
  41     geometry->m_thumbSize = m_thumbSize;
  42     return geometry;
  43 }
  44
  45 int CCScrollbarGeometryFixedThumb::thumbLength(WebScrollbar* scrollbar)
  46 {
  47     if (scrollbar->orientation() == WebScrollbar::Horizontal)
  48         return m_thumbSize.width();
  49     return m_thumbSize.height();
  50 }
  51
  52 int CCScrollbarGeometryFixedThumb::thumbPosition(WebScrollbar* scrollbar)
  53 {
  54     if (scrollbar->enabled()) {
  55         float size = scrollbar->maximum();
  56         if (!size)
  57             return 1;
  58         int value = std::min(std::max(0, scrollbar->value()), scrollbar->maximum());
  59         float pos = (trackLength(scrollbar) - thumbLength(scrollbar)) * value / size;
  60         return static_cast<int>(floorf((pos < 1 && pos > 0) ? 1 : pos));
  61     }
  62     return 0;
  63 }
  64 void CCScrollbarGeometryFixedThumb::splitTrack(WebScrollbar* scrollbar, const WebRect& unconstrainedTrackRect, WebRect& beforeThumbRect, WebRect& thumbRect, WebRect& afterThumbRect)
  65 {
  66     // This is a reimplementation of ScrollbarThemeComposite::splitTrack.
  67     // Because the WebScrollbarThemeGeometry functions call down to native
  68     // ScrollbarThemeComposite code which uses ScrollbarThemeComposite virtual
  69     // helpers, there's no way to override a helper like thumbLength from
  70     // the WebScrollbarThemeGeometry level. So, these three functions
  71     // (splitTrack, thumbPosition, thumbLength) are copied here so that the
  72     // WebScrollbarThemeGeometry helper functions are used instead and
  73     // a fixed size thumbLength can be used.
  74
  75     WebRect trackRect = constrainTrackRectToTrackPieces(scrollbar, unconstrainedTrackRect);
  76     int thickness = scrollbar->orientation() == WebScrollbar::Horizontal ? scrollbar->size().height : scrollbar->size().width;
  77     int thumbPos = thumbPosition(scrollbar);
  78     if (scrollbar->orientation() == WebScrollbar::Horizontal) {
  79         thumbRect = WebRect(trackRect.x + thumbPos, trackRect.y + (trackRect.height - thickness) / 2, thumbLength(scrollbar), thickness);
  80         beforeThumbRect = WebRect(trackRect.x, trackRect.y, thumbPos + thumbRect.width / 2, trackRect.height);
  81         afterThumbRect = WebRect(trackRect.x + beforeThumbRect.width, trackRect.y, trackRect.x + trackRect.width - beforeThumbRect.x - beforeThumbRect.width, trackRect.height);
  82     } else {
  83         thumbRect = WebRect(trackRect.x + (trackRect.width - thickness) / 2, trackRect.y + thumbPos, thickness, thumbLength(scrollbar));
  84         beforeThumbRect = WebRect(trackRect.x, trackRect.y, trackRect.width, thumbPos + thumbRect.height / 2);
  85         afterThumbRect = WebRect(trackRect.x, trackRect.y + beforeThumbRect.height, trackRect.width, trackRect.y + trackRect.height - beforeThumbRect.y - beforeThumbRect.height);
  86     }
  87 }
  88
  89 CCScrollbarGeometryFixedThumb::CCScrollbarGeometryFixedThumb(PassOwnPtr<WebScrollbarThemeGeometry> geometry)
  90     : CCScrollbarGeometryStub(geometry)
  91 {
  92 }
  93
  94 }