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
11namespace cc {
12
13ScrollbarLayerImplBase::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
31ScrollbarLayerImplBase::~ScrollbarLayerImplBase() {}
32
33void 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
42void ScrollbarLayerImplBase::PushScrollClipPropertiesTo(LayerImpl* layer) {
43  DCHECK(layer->ToScrollbarLayer());
44  layer->ToScrollbarLayer()->SetScrollLayerAndClipLayerByIds(ScrollLayerId(),
45                                                             ClipLayerId());
46}
47
48ScrollbarLayerImplBase* ScrollbarLayerImplBase::ToScrollbarLayer() {
49  return this;
50}
51
52namespace {
53
54typedef void (LayerImpl::*ScrollbarRegistrationOperation)(
55    ScrollbarLayerImplBase*);
56
57void 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
80void 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
98gfx::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
108bool 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
116bool ScrollbarLayerImplBase::SetMaximum(int maximum) {
117  if (maximum_ == maximum)
118    return false;
119  maximum_ = maximum;
120  NoteLayerPropertyChanged();
121  return true;
122}
123
124bool 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
132bool 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
143bool 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
151gfx::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
250void ScrollbarLayerImplBase::ScrollbarParametersDidChange() {
251  if (!clip_layer_ || !scroll_layer_)
252    return;
253
254  scroll_layer_->SetScrollbarPosition(this, clip_layer_);
255}
256
257}  // namespace cc
258