1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <set>
#include "base/logging.h"
#include "cc/trees/property_tree.h"
namespace cc {
template <typename T>
PropertyTree<T>::PropertyTree() {
nodes_.push_back(T());
back()->id = 0;
back()->parent_id = -1;
}
template <typename T>
PropertyTree<T>::~PropertyTree() {
}
template <typename T>
int PropertyTree<T>::Insert(const T& tree_node, int parent_id) {
DCHECK_GT(nodes_.size(), 0u);
nodes_.push_back(tree_node);
T& node = nodes_.back();
node.parent_id = parent_id;
node.id = static_cast<int>(nodes_.size()) - 1;
return node.id;
}
template class PropertyTree<TransformNode>;
template class PropertyTree<ClipNode>;
TransformNodeData::TransformNodeData()
: target_id(-1),
is_invertible(true),
ancestors_are_invertible(true),
is_animated(false),
to_screen_is_animated(false),
flattens(false) {
}
TransformNodeData::~TransformNodeData() {
}
ClipNodeData::ClipNodeData() : transform_id(-1), target_id(-1) {
}
bool TransformTree::ComputeTransform(int source_id,
int dest_id,
gfx::Transform* transform) const {
transform->MakeIdentity();
if (source_id == dest_id)
return true;
if (source_id > dest_id && IsDescendant(source_id, dest_id))
return CombineTransformsBetween(source_id, dest_id, transform);
if (dest_id > source_id && IsDescendant(dest_id, source_id))
return CombineInversesBetween(source_id, dest_id, transform);
int lca = LowestCommonAncestor(source_id, dest_id);
bool no_singular_matrices_to_lca =
CombineTransformsBetween(source_id, lca, transform);
bool no_singular_matrices_from_lca =
CombineInversesBetween(lca, dest_id, transform);
return no_singular_matrices_to_lca && no_singular_matrices_from_lca;
}
bool TransformTree::Are2DAxisAligned(int source_id, int dest_id) const {
gfx::Transform transform;
return ComputeTransform(source_id, dest_id, &transform) &&
transform.Preserves2dAxisAlignment();
}
void TransformTree::UpdateScreenSpaceTransform(int id) {
TransformNode* current_node = Node(id);
TransformNode* parent_node = parent(current_node);
TransformNode* target_node = Node(current_node->data.target_id);
if (!parent_node) {
current_node->data.to_screen = current_node->data.to_parent;
current_node->data.ancestors_are_invertible = true;
current_node->data.to_screen_is_animated = false;
} else if (parent_node->data.flattens) {
// Flattening is tricky. Once a layer is drawn into its render target, it
// cannot escape, so we only need to consider transforms between the layer
// and its target when flattening (i.e., its draw transform). To compute the
// screen space transform when flattening is involved we combine three
// transforms, A * B * C, where A is the screen space transform of the
// target, B is the flattened draw transform of the layer's parent, and C is
// the local transform.
current_node->data.to_screen = target_node->data.to_screen;
gfx::Transform flattened;
ComputeTransform(parent_node->id, target_node->id, &flattened);
flattened.FlattenTo2d();
current_node->data.to_screen.PreconcatTransform(flattened);
current_node->data.to_screen.PreconcatTransform(
current_node->data.to_parent);
current_node->data.ancestors_are_invertible =
parent_node->data.ancestors_are_invertible;
} else {
current_node->data.to_screen = parent_node->data.to_screen;
current_node->data.to_screen.PreconcatTransform(
current_node->data.to_parent);
current_node->data.ancestors_are_invertible =
parent_node->data.ancestors_are_invertible;
}
if (!current_node->data.to_screen.GetInverse(¤t_node->data.from_screen))
current_node->data.ancestors_are_invertible = false;
if (parent_node) {
current_node->data.to_screen_is_animated =
current_node->data.is_animated ||
parent_node->data.to_screen_is_animated;
}
}
bool TransformTree::IsDescendant(int desc_id, int source_id) const {
while (desc_id != source_id) {
if (desc_id < 0)
return false;
desc_id = Node(desc_id)->parent_id;
}
return true;
}
int TransformTree::LowestCommonAncestor(int a, int b) const {
std::set<int> chain_a;
std::set<int> chain_b;
while (a || b) {
if (a) {
a = Node(a)->parent_id;
if (a > -1 && chain_b.find(a) != chain_b.end())
return a;
chain_a.insert(a);
}
if (b) {
b = Node(b)->parent_id;
if (b > -1 && chain_a.find(b) != chain_a.end())
return b;
chain_b.insert(b);
}
}
NOTREACHED();
return 0;
}
bool TransformTree::CombineTransformsBetween(int source_id,
int dest_id,
gfx::Transform* transform) const {
const TransformNode* current = Node(source_id);
const TransformNode* dest = Node(dest_id);
if (!dest || dest->data.ancestors_are_invertible) {
transform->ConcatTransform(current->data.to_screen);
if (dest)
transform->ConcatTransform(dest->data.from_screen);
return true;
}
bool all_are_invertible = true;
for (; current && current->id > dest_id; current = parent(current)) {
transform->ConcatTransform(current->data.to_parent);
if (!current->data.is_invertible)
all_are_invertible = false;
}
return all_are_invertible;
}
bool TransformTree::CombineInversesBetween(int source_id,
int dest_id,
gfx::Transform* transform) const {
const TransformNode* current = Node(dest_id);
const TransformNode* dest = Node(source_id);
if (current->data.ancestors_are_invertible) {
transform->PreconcatTransform(current->data.from_screen);
if (dest)
transform->PreconcatTransform(dest->data.to_screen);
return true;
}
bool all_are_invertible = true;
for (; current && current->id > source_id; current = parent(current)) {
transform->PreconcatTransform(current->data.from_parent);
if (!current->data.is_invertible)
all_are_invertible = false;
}
return all_are_invertible;
}
} // namespace cc
|
