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/trees/layer_tree_impl.h"
9 #include "ui/gfx/rect_conversions.h"
10
11 namespace cc {
12
ScrollbarLayerImplBase(LayerTreeImpl * tree_impl,int id,ScrollbarOrientation orientation,bool is_left_side_vertical_scrollbar,bool is_overlay)13 ScrollbarLayerImplBase::ScrollbarLayerImplBase(
14 LayerTreeImpl* tree_impl,
15 int id,
16 ScrollbarOrientation orientation,
17 bool is_left_side_vertical_scrollbar,
18 bool is_overlay)
19 : LayerImpl(tree_impl, id),
20 scroll_layer_(NULL),
21 clip_layer_(NULL),
22 is_overlay_scrollbar_(is_overlay),
23 thumb_thickness_scale_factor_(1.f),
24 current_pos_(0.f),
25 maximum_(0),
26 orientation_(orientation),
27 is_left_side_vertical_scrollbar_(is_left_side_vertical_scrollbar),
28 vertical_adjust_(0.f),
29 visible_to_total_length_ratio_(1.f) {}
30
~ScrollbarLayerImplBase()31 ScrollbarLayerImplBase::~ScrollbarLayerImplBase() {}
32
PushPropertiesTo(LayerImpl * layer)33 void ScrollbarLayerImplBase::PushPropertiesTo(LayerImpl* layer) {
34 float active_opacity = layer->opacity();
35 LayerImpl::PushPropertiesTo(layer);
36 layer->SetOpacity(active_opacity);
37 DCHECK(layer->ToScrollbarLayer());
38 layer->ToScrollbarLayer()->set_is_overlay_scrollbar(is_overlay_scrollbar_);
39 PushScrollClipPropertiesTo(layer);
40 }
41
PushScrollClipPropertiesTo(LayerImpl * layer)42 void ScrollbarLayerImplBase::PushScrollClipPropertiesTo(LayerImpl* layer) {
43 DCHECK(layer->ToScrollbarLayer());
44 layer->ToScrollbarLayer()->SetScrollLayerAndClipLayerByIds(ScrollLayerId(),
45 ClipLayerId());
46 }
47
ToScrollbarLayer()48 ScrollbarLayerImplBase* ScrollbarLayerImplBase::ToScrollbarLayer() {
49 return this;
50 }
51
52 namespace {
53
54 typedef void (LayerImpl::*ScrollbarRegistrationOperation)(
55 ScrollbarLayerImplBase*);
56
RegisterScrollbarWithLayers(ScrollbarLayerImplBase * scrollbar,LayerImpl * container_layer,LayerImpl * scroll_layer,ScrollbarRegistrationOperation operation)57 void RegisterScrollbarWithLayers(ScrollbarLayerImplBase* scrollbar,
58 LayerImpl* container_layer,
59 LayerImpl* scroll_layer,
60 ScrollbarRegistrationOperation operation) {
61 if (!container_layer || !scroll_layer)
62 return;
63
64 DCHECK(scrollbar);
65
66 // Scrollbars must be notifed of changes to their scroll and container layers
67 // and all scrollable layers in between.
68 for (LayerImpl* current_layer = scroll_layer;
69 current_layer && current_layer != container_layer->parent();
70 current_layer = current_layer->parent()) {
71 // TODO(wjmaclean) We shouldn't need to exempt the scroll_layer from the
72 // scrollable() test below. https://crbug.com/367858.
73 if (current_layer->scrollable() || current_layer == container_layer ||
74 current_layer == scroll_layer)
75 (current_layer->*operation)(scrollbar);
76 }
77 }
78 } // namespace
79
SetScrollLayerAndClipLayerByIds(int scroll_layer_id,int clip_layer_id)80 void ScrollbarLayerImplBase::SetScrollLayerAndClipLayerByIds(
81 int scroll_layer_id,
82 int clip_layer_id) {
83 LayerImpl* scroll_layer = layer_tree_impl()->LayerById(scroll_layer_id);
84 LayerImpl* clip_layer = layer_tree_impl()->LayerById(clip_layer_id);
85 if (scroll_layer_ == scroll_layer && clip_layer_ == clip_layer)
86 return;
87
88 RegisterScrollbarWithLayers(
89 this, clip_layer_, scroll_layer_, &LayerImpl::RemoveScrollbar);
90 scroll_layer_ = scroll_layer;
91 clip_layer_ = clip_layer;
92 RegisterScrollbarWithLayers(
93 this, clip_layer_, scroll_layer_, &LayerImpl::AddScrollbar);
94
95 ScrollbarParametersDidChange();
96 }
97
ScrollbarLayerRectToContentRect(const gfx::RectF & layer_rect) const98 gfx::Rect ScrollbarLayerImplBase::ScrollbarLayerRectToContentRect(
99 const gfx::RectF& layer_rect) const {
100 // Don't intersect with the bounds as in LayerRectToContentRect() because
101 // layer_rect here might be in coordinates of the containing layer.
102 gfx::RectF content_rect = gfx::ScaleRect(layer_rect,
103 contents_scale_x(),
104 contents_scale_y());
105 return gfx::ToEnclosingRect(content_rect);
106 }
107
SetCurrentPos(float current_pos)108 bool ScrollbarLayerImplBase::SetCurrentPos(float current_pos) {
109 if (current_pos_ == current_pos)
110 return false;
111 current_pos_ = current_pos;
112 NoteLayerPropertyChanged();
113 return true;
114 }
115
SetMaximum(int maximum)116 bool ScrollbarLayerImplBase::SetMaximum(int maximum) {
117 if (maximum_ == maximum)
118 return false;
119 maximum_ = maximum;
120 NoteLayerPropertyChanged();
121 return true;
122 }
123
SetVerticalAdjust(float vertical_adjust)124 bool ScrollbarLayerImplBase::SetVerticalAdjust(float vertical_adjust) {
125 if (vertical_adjust_ == vertical_adjust)
126 return false;
127 vertical_adjust_ = vertical_adjust;
128 NoteLayerPropertyChanged();
129 return true;
130 }
131
SetVisibleToTotalLengthRatio(float ratio)132 bool ScrollbarLayerImplBase::SetVisibleToTotalLengthRatio(float ratio) {
133 if (!IsThumbResizable())
134 return false;
135
136 if (visible_to_total_length_ratio_ == ratio)
137 return false;
138 visible_to_total_length_ratio_ = ratio;
139 NoteLayerPropertyChanged();
140 return true;
141 }
142
SetThumbThicknessScaleFactor(float factor)143 bool ScrollbarLayerImplBase::SetThumbThicknessScaleFactor(float factor) {
144 if (thumb_thickness_scale_factor_ == factor)
145 return false;
146 thumb_thickness_scale_factor_ = factor;
147 NoteLayerPropertyChanged();
148 return true;
149 }
150
ComputeThumbQuadRect() const151 gfx::Rect ScrollbarLayerImplBase::ComputeThumbQuadRect() const {
152 // Thumb extent is the length of the thumb in the scrolling direction, thumb
153 // thickness is in the perpendicular direction. Here's an example of a
154 // horizontal scrollbar - inputs are above the scrollbar, computed values
155 // below:
156 //
157 // |<------------------- track_length_ ------------------->|
158 //
159 // |--| <-- start_offset
160 //
161 // +--+----------------------------+------------------+-------+--+
162 // |<|| |##################| ||>|
163 // +--+----------------------------+------------------+-------+--+
164 //
165 // |<- thumb_length ->|
166 //
167 // |<------- thumb_offset -------->|
168 //
169 // For painted, scrollbars, the length is fixed. For solid color scrollbars we
170 // have to compute it. The ratio of the thumb's length to the track's length
171 // is the same as that of the visible viewport to the total viewport, unless
172 // that would make the thumb's length less than its thickness.
173 //
174 // vertical_adjust_ is used when the layer geometry from the main thread is
175 // not in sync with what the user sees. For instance on Android scrolling the
176 // top bar controls out of view reveals more of the page content. We want the
177 // root layer scrollbars to reflect what the user sees even if we haven't
178 // received new layer geometry from the main thread. If the user has scrolled
179 // down by 50px and the initial viewport size was 950px the geometry would
180 // look something like this:
181 //
182 // vertical_adjust_ = 50, scroll position 0, visible ratios 99%
183 // Layer geometry: Desired thumb positions:
184 // +--------------------+-+ +----------------------+ <-- 0px
185 // | |v| | #|
186 // | |e| | #|
187 // | |r| | #|
188 // | |t| | #|
189 // | |i| | #|
190 // | |c| | #|
191 // | |a| | #|
192 // | |l| | #|
193 // | | | | #|
194 // | |l| | #|
195 // | |a| | #|
196 // | |y| | #|
197 // | |e| | #|
198 // | |r| | #|
199 // +--------------------+-+ | #|
200 // | horizontal layer | | | #|
201 // +--------------------+-+ | #| <-- 950px
202 // | | | #|
203 // | | |##################### |
204 // +----------------------+ +----------------------+ <-- 1000px
205 //
206 // The layer geometry is set up for a 950px tall viewport, but the user can
207 // actually see down to 1000px. Thus we have to move the quad for the
208 // horizontal scrollbar down by the vertical_adjust_ factor and lay the
209 // vertical thumb out on a track lengthed by the vertical_adjust_ factor. This
210 // means the quads may extend outside the layer's bounds.
211
212 // With the length known, we can compute the thumb's position.
213 float track_length = TrackLength();
214 int thumb_length = ThumbLength();
215 int thumb_thickness = ThumbThickness();
216
217 // With the length known, we can compute the thumb's position.
218 float clamped_current_pos =
219 std::min(std::max(current_pos_, 0.f), static_cast<float>(maximum_));
220
221 int thumb_offset = TrackStart();
222 if (maximum_ > 0) {
223 float ratio = clamped_current_pos / maximum_;
224 float max_offset = track_length - thumb_length;
225 thumb_offset += static_cast<int>(ratio * max_offset);
226 }
227
228 float thumb_thickness_adjustment =
229 thumb_thickness * (1.f - thumb_thickness_scale_factor_);
230
231 gfx::RectF thumb_rect;
232 if (orientation_ == HORIZONTAL) {
233 thumb_rect = gfx::RectF(thumb_offset,
234 vertical_adjust_ + thumb_thickness_adjustment,
235 thumb_length,
236 thumb_thickness - thumb_thickness_adjustment);
237 } else {
238 thumb_rect = gfx::RectF(
239 is_left_side_vertical_scrollbar_
240 ? bounds().width() - thumb_thickness
241 : thumb_thickness_adjustment,
242 thumb_offset,
243 thumb_thickness - thumb_thickness_adjustment,
244 thumb_length);
245 }
246
247 return ScrollbarLayerRectToContentRect(thumb_rect);
248 }
249
ScrollbarParametersDidChange()250 void ScrollbarLayerImplBase::ScrollbarParametersDidChange() {
251 if (!clip_layer_ || !scroll_layer_)
252 return;
253
254 scroll_layer_->SetScrollbarPosition(this, clip_layer_);
255 }
256
257 } // namespace cc
258