1 // Copyright 2013 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/layers/scrollbar_layer_impl_base.h" 6 7 #include <algorithm> 8 #include "cc/layers/layer.h" 9 #include "ui/gfx/rect_conversions.h" 10 11 namespace cc { 12 13 ScrollbarLayerImplBase::ScrollbarLayerImplBase( 14 LayerTreeImpl* tree_impl, 15 int id, 16 ScrollbarOrientation orientation, 17 bool is_left_side_vertical_scrollbar) 18 : LayerImpl(tree_impl, id), 19 scroll_layer_id_(Layer::INVALID_ID), 20 is_overlay_scrollbar_(false), 21 thumb_thickness_scale_factor_(1.f), 22 current_pos_(0.f), 23 maximum_(0), 24 orientation_(orientation), 25 is_left_side_vertical_scrollbar_(is_left_side_vertical_scrollbar), 26 vertical_adjust_(0.f), 27 visible_to_total_length_ratio_(1.f) {} 28 29 void ScrollbarLayerImplBase::PushPropertiesTo(LayerImpl* layer) { 30 LayerImpl::PushPropertiesTo(layer); 31 } 32 33 ScrollbarLayerImplBase* ScrollbarLayerImplBase::ToScrollbarLayer() { 34 return this; 35 } 36 37 gfx::Rect ScrollbarLayerImplBase::ScrollbarLayerRectToContentRect( 38 gfx::RectF layer_rect) const { 39 // Don't intersect with the bounds as in LayerRectToContentRect() because 40 // layer_rect here might be in coordinates of the containing layer. 41 gfx::RectF content_rect = gfx::ScaleRect(layer_rect, 42 contents_scale_x(), 43 contents_scale_y()); 44 return gfx::ToEnclosingRect(content_rect); 45 } 46 47 void ScrollbarLayerImplBase::SetCurrentPos(float current_pos) { 48 if (current_pos_ == current_pos) 49 return; 50 current_pos_ = current_pos; 51 NoteLayerPropertyChanged(); 52 } 53 54 void ScrollbarLayerImplBase::SetMaximum(int maximum) { 55 if (maximum_ == maximum) 56 return; 57 maximum_ = maximum; 58 NoteLayerPropertyChanged(); 59 } 60 61 void ScrollbarLayerImplBase::SetVerticalAdjust(float vertical_adjust) { 62 if (vertical_adjust_ == vertical_adjust) 63 return; 64 vertical_adjust_ = vertical_adjust; 65 NoteLayerPropertyChanged(); 66 } 67 68 void ScrollbarLayerImplBase::SetVisibleToTotalLengthRatio(float ratio) { 69 if (visible_to_total_length_ratio_ == ratio) 70 return; 71 visible_to_total_length_ratio_ = ratio; 72 NoteLayerPropertyChanged(); 73 } 74 75 void ScrollbarLayerImplBase::SetThumbThicknessScaleFactor(float factor) { 76 if (thumb_thickness_scale_factor_ == factor) 77 return; 78 thumb_thickness_scale_factor_ = factor; 79 NoteLayerPropertyChanged(); 80 } 81 82 gfx::Rect ScrollbarLayerImplBase::ComputeThumbQuadRect() const { 83 // Thumb extent is the length of the thumb in the scrolling direction, thumb 84 // thickness is in the perpendicular direction. Here's an example of a 85 // horizontal scrollbar - inputs are above the scrollbar, computed values 86 // below: 87 // 88 // |<------------------- track_length_ ------------------->| 89 // 90 // |--| <-- start_offset 91 // 92 // +--+----------------------------+------------------+-------+--+ 93 // |<|| |##################| ||>| 94 // +--+----------------------------+------------------+-------+--+ 95 // 96 // |<- thumb_length ->| 97 // 98 // |<------- thumb_offset -------->| 99 // 100 // For painted, scrollbars, the length is fixed. For solid color scrollbars we 101 // have to compute it. The ratio of the thumb's length to the track's length 102 // is the same as that of the visible viewport to the total viewport, unless 103 // that would make the thumb's length less than its thickness. 104 // 105 // vertical_adjust_ is used when the layer geometry from the main thread is 106 // not in sync with what the user sees. For instance on Android scrolling the 107 // top bar controls out of view reveals more of the page content. We want the 108 // root layer scrollbars to reflect what the user sees even if we haven't 109 // received new layer geometry from the main thread. If the user has scrolled 110 // down by 50px and the initial viewport size was 950px the geometry would 111 // look something like this: 112 // 113 // vertical_adjust_ = 50, scroll position 0, visible ratios 99% 114 // Layer geometry: Desired thumb positions: 115 // +--------------------+-+ +----------------------+ <-- 0px 116 // | |v| | #| 117 // | |e| | #| 118 // | |r| | #| 119 // | |t| | #| 120 // | |i| | #| 121 // | |c| | #| 122 // | |a| | #| 123 // | |l| | #| 124 // | | | | #| 125 // | |l| | #| 126 // | |a| | #| 127 // | |y| | #| 128 // | |e| | #| 129 // | |r| | #| 130 // +--------------------+-+ | #| 131 // | horizontal layer | | | #| 132 // +--------------------+-+ | #| <-- 950px 133 // | | | #| 134 // | | |##################### | 135 // +----------------------+ +----------------------+ <-- 1000px 136 // 137 // The layer geometry is set up for a 950px tall viewport, but the user can 138 // actually see down to 1000px. Thus we have to move the quad for the 139 // horizontal scrollbar down by the vertical_adjust_ factor and lay the 140 // vertical thumb out on a track lengthed by the vertical_adjust_ factor. This 141 // means the quads may extend outside the layer's bounds. 142 143 // With the length known, we can compute the thumb's position. 144 float track_length = TrackLength(); 145 int thumb_length = ThumbLength(); 146 int thumb_thickness = ThumbThickness(); 147 148 // With the length known, we can compute the thumb's position. 149 float clamped_current_pos = 150 std::min(std::max(current_pos_, 0.f), static_cast<float>(maximum_)); 151 float ratio = clamped_current_pos / maximum_; 152 float max_offset = track_length - thumb_length; 153 int thumb_offset = static_cast<int>(ratio * max_offset) + TrackStart(); 154 155 float thumb_thickness_adjustment = 156 thumb_thickness * (1.f - thumb_thickness_scale_factor_); 157 158 gfx::RectF thumb_rect; 159 if (orientation_ == HORIZONTAL) { 160 thumb_rect = gfx::RectF(thumb_offset, 161 vertical_adjust_ + thumb_thickness_adjustment, 162 thumb_length, 163 thumb_thickness - thumb_thickness_adjustment); 164 } else { 165 thumb_rect = gfx::RectF( 166 is_left_side_vertical_scrollbar_ 167 ? bounds().width() - thumb_thickness 168 : thumb_thickness_adjustment, 169 thumb_offset, 170 thumb_thickness - thumb_thickness_adjustment, 171 thumb_length); 172 } 173 174 return ScrollbarLayerRectToContentRect(thumb_rect); 175 } 176 177 } // namespace cc 178
