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
200
201
202
203
204
|
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef GFX_READBACKLAYER_H
#define GFX_READBACKLAYER_H
#include <stdint.h> // for uint64_t
#include "Layers.h" // for Layer, etc
#include "mozilla/gfx/Rect.h" // for gfxRect
#include "mozilla/gfx/Point.h" // for IntPoint
#include "mozilla/mozalloc.h" // for operator delete
#include "nsAutoPtr.h" // for nsAutoPtr
#include "nsCOMPtr.h" // for already_AddRefed
#include "nsDebug.h" // for NS_ASSERTION
#include "nsPoint.h" // for nsIntPoint
#include "nscore.h" // for nsACString
class gfxContext;
namespace mozilla {
namespace layers {
class ReadbackProcessor;
namespace layerscope {
class LayersPacket;
} // namespace layerscope
/**
* A ReadbackSink receives a stream of updates to a rectangle of pixels.
* These update callbacks are always called on the main thread, either during
* EndTransaction or from the event loop.
*/
class ReadbackSink {
public:
ReadbackSink() {}
virtual ~ReadbackSink() {}
/**
* Sends an update to indicate that the background is currently unknown.
*/
virtual void SetUnknown(uint64_t aSequenceNumber) = 0;
/**
* Called by the layer system to indicate that the contents of part of
* the readback area are changing.
* @param aRect is the rectangle of content that is being updated,
* in the coordinate system of the ReadbackLayer.
* @param aSequenceNumber updates issued out of order should be ignored.
* Only use updates whose sequence counter is greater than all other updates
* seen so far. Return null when a non-fresh sequence value is given.
* @return a context into which the update should be drawn. This should be
* set up to clip to aRect. Zero should never be passed as a sequence number.
* If this returns null, EndUpdate should NOT be called. If it returns
* non-null, EndUpdate must be called.
*
* We don't support partially unknown backgrounds. Therefore, the
* first BeginUpdate after a SetUnknown will have the complete background.
*/
virtual already_AddRefed<gfx::DrawTarget>
BeginUpdate(const gfx::IntRect& aRect, uint64_t aSequenceNumber) = 0;
/**
* EndUpdate must be called immediately after BeginUpdate, without returning
* to the event loop.
* @param aContext the context returned by BeginUpdate
* Implicitly Restore()s the state of aContext.
*/
virtual void EndUpdate(const gfx::IntRect& aRect) = 0;
};
/**
* A ReadbackLayer never renders anything. It enables clients to extract
* the rendered contents of the layer tree below the ReadbackLayer.
* The rendered contents are delivered asynchronously via calls to a
* ReadbackSink object supplied by the client.
*
* This is a "best effort" API; it is possible for the layer system to tell
* the ReadbackSink that the contents of the readback area are unknown.
*
* This API exists to work around the limitations of transparent windowless
* plugin rendering APIs. It should not be used for anything else.
*/
class ReadbackLayer : public Layer {
public:
MOZ_LAYER_DECL_NAME("ReadbackLayer", TYPE_READBACK)
virtual void ComputeEffectiveTransforms(const gfx::Matrix4x4& aTransformToSurface) override
{
// Snap our local transform first, and snap the inherited transform as well.
// This makes our snapping equivalent to what would happen if our content
// was drawn into a PaintedLayer (gfxContext would snap using the local
// transform, then we'd snap again when compositing the PaintedLayer).
mEffectiveTransform =
SnapTransform(GetLocalTransform(), gfxRect(0, 0, mSize.width, mSize.height),
nullptr)*
SnapTransformTranslation(aTransformToSurface, nullptr);
}
/**
* CONSTRUCTION PHASE ONLY
* Set the callback object to which readback updates will be delivered.
* This also resets the "needed rectangle" so that on the next layer tree
* transaction we will try to deliver the full contents of the readback
* area to the sink.
* This layer takes ownership of the sink. It will be deleted when the
* layer is destroyed or when a new sink is set.
* Initially the contents of the readback area are completely unknown.
*/
void SetSink(ReadbackSink* aSink)
{
SetUnknown();
mSink = aSink;
}
ReadbackSink* GetSink() { return mSink; }
/**
* CONSTRUCTION PHASE ONLY
* Set the size of content that should be read back. The readback area
* has its top-left at 0,0 and has size aSize.
* Can only be called while the sink is null!
*/
void SetSize(const gfx::IntSize& aSize)
{
NS_ASSERTION(!mSink, "Should have no sink while changing size!");
mSize = aSize;
}
const gfx::IntSize& GetSize() { return mSize; }
gfx::IntRect GetRect() { return gfx::IntRect(gfx::IntPoint(0, 0), mSize); }
bool IsBackgroundKnown()
{
return mBackgroundLayer || mBackgroundColor.a == 1.f;
}
void NotifyRemoved() {
SetUnknown();
mSink = nullptr;
}
void NotifyPaintedLayerRemoved(PaintedLayer* aLayer)
{
if (mBackgroundLayer == aLayer) {
mBackgroundLayer = nullptr;
}
}
const nsIntPoint& GetBackgroundLayerOffset() { return mBackgroundLayerOffset; }
uint64_t AllocateSequenceNumber() { return ++mSequenceCounter; }
void SetUnknown()
{
if (IsBackgroundKnown()) {
if (mSink) {
mSink->SetUnknown(AllocateSequenceNumber());
}
mBackgroundLayer = nullptr;
mBackgroundColor = gfx::Color();
}
}
protected:
friend class ReadbackProcessor;
ReadbackLayer(LayerManager* aManager, void* aImplData) :
Layer(aManager, aImplData),
mSequenceCounter(0),
mSize(0,0),
mBackgroundLayer(nullptr),
mBackgroundLayerOffset(0, 0),
mBackgroundColor(gfx::Color())
{}
virtual void PrintInfo(std::stringstream& aStream, const char* aPrefix) override;
virtual void DumpPacket(layerscope::LayersPacket* aPacket, const void* aParent) override;
uint64_t mSequenceCounter;
nsAutoPtr<ReadbackSink> mSink;
gfx::IntSize mSize;
// This can refer to any (earlier) sibling PaintedLayer. That PaintedLayer
// must have mUsedForReadback set on it. If the PaintedLayer is removed
// for the container, this will be set to null by NotifyPaintedLayerRemoved.
// This PaintedLayer contains the contents which have previously been reported
// to mSink. The PaintedLayer had only an integer translation transform,
// and it covered the entire readback area. This layer also had only an
// integer translation transform.
PaintedLayer* mBackgroundLayer;
// When mBackgroundLayer is non-null, this is the offset to add to
// convert from the coordinates of mBackgroundLayer to the coordinates
// of this layer.
nsIntPoint mBackgroundLayerOffset;
// When mBackgroundColor is opaque, this is the color of the ColorLayer
// that contained the contents we reported to mSink, which covered the
// entire readback area.
gfx::Color mBackgroundColor;
};
} // namespace layers
} // namespace mozilla
#endif /* GFX_READBACKLAYER_H */
|
