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1 /*
2  * Copyright 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
18 #define ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
19 
20 #include <gui/ConsumerBase.h>
21 #include <gui/IGraphicBufferProducer.h>
22 
23 #include "DisplaySurface.h"
24 
25 // ---------------------------------------------------------------------------
26 namespace android {
27 // ---------------------------------------------------------------------------
28 
29 class HWComposer;
30 class IProducerListener;
31 
32 /* This DisplaySurface implementation supports virtual displays, where GLES
33  * and/or HWC compose into a buffer that is then passed to an arbitrary
34  * consumer (the sink) running in another process.
35  *
36  * The simplest case is when the virtual display will never use the h/w
37  * composer -- either the h/w composer doesn't support writing to buffers, or
38  * there are more virtual displays than it supports simultaneously. In this
39  * case, the GLES driver works directly with the output buffer queue, and
40  * calls to the VirtualDisplay from SurfaceFlinger and DisplayHardware do
41  * nothing.
42  *
43  * If h/w composer might be used, then each frame will fall into one of three
44  * configurations: GLES-only, HWC-only, and MIXED composition. In all of these,
45  * we must provide a FB target buffer and output buffer for the HWC set() call.
46  *
47  * In GLES-only composition, the GLES driver is given a buffer from the sink to
48  * render into. When the GLES driver queues the buffer to the
49  * VirtualDisplaySurface, the VirtualDisplaySurface holds onto it instead of
50  * immediately queueing it to the sink. The buffer is used as both the FB
51  * target and output buffer for HWC, though on these frames the HWC doesn't
52  * do any work for this display and doesn't write to the output buffer. After
53  * composition is complete, the buffer is queued to the sink.
54  *
55  * In HWC-only composition, the VirtualDisplaySurface dequeues a buffer from
56  * the sink and passes it to HWC as both the FB target buffer and output
57  * buffer. The HWC doesn't need to read from the FB target buffer, but does
58  * write to the output buffer. After composition is complete, the buffer is
59  * queued to the sink.
60  *
61  * On MIXED frames, things become more complicated, since some h/w composer
62  * implementations can't read from and write to the same buffer. This class has
63  * an internal BufferQueue that it uses as a scratch buffer pool. The GLES
64  * driver is given a scratch buffer to render into. When it finishes rendering,
65  * the buffer is queued and then immediately acquired by the
66  * VirtualDisplaySurface. The scratch buffer is then used as the FB target
67  * buffer for HWC, and a separate buffer is dequeued from the sink and used as
68  * the HWC output buffer. When HWC composition is complete, the scratch buffer
69  * is released and the output buffer is queued to the sink.
70  */
71 class VirtualDisplaySurface : public DisplaySurface,
72                               public BnGraphicBufferProducer,
73                               private ConsumerBase {
74 public:
75     VirtualDisplaySurface(HWComposer& hwc, int32_t dispId,
76             const sp<IGraphicBufferProducer>& sink,
77             const sp<IGraphicBufferProducer>& bqProducer,
78             const sp<IGraphicBufferConsumer>& bqConsumer,
79             const String8& name);
80 
81     //
82     // DisplaySurface interface
83     //
84     virtual status_t beginFrame(bool mustRecompose);
85     virtual status_t prepareFrame(CompositionType compositionType);
86     virtual status_t compositionComplete();
87     virtual status_t advanceFrame();
88     virtual void onFrameCommitted();
89     virtual void dump(String8& result) const;
90     virtual void resizeBuffers(const uint32_t w, const uint32_t h);
91 
92 private:
93     enum Source {SOURCE_SINK = 0, SOURCE_SCRATCH = 1};
94 
95     virtual ~VirtualDisplaySurface();
96 
97     //
98     // IGraphicBufferProducer interface, used by the GLES driver.
99     //
100     virtual status_t requestBuffer(int pslot, sp<GraphicBuffer>* outBuf);
101     virtual status_t setBufferCount(int bufferCount);
102     virtual status_t dequeueBuffer(int* pslot, sp<Fence>* fence, bool async,
103             uint32_t w, uint32_t h, uint32_t format, uint32_t usage);
104     virtual status_t detachBuffer(int slot);
105     virtual status_t detachNextBuffer(sp<GraphicBuffer>* outBuffer,
106             sp<Fence>* outFence);
107     virtual status_t attachBuffer(int* slot, const sp<GraphicBuffer>& buffer);
108     virtual status_t queueBuffer(int pslot,
109             const QueueBufferInput& input, QueueBufferOutput* output);
110     virtual void cancelBuffer(int pslot, const sp<Fence>& fence);
111     virtual int query(int what, int* value);
112     virtual status_t connect(const sp<IProducerListener>& listener,
113             int api, bool producerControlledByApp, QueueBufferOutput* output);
114     virtual status_t disconnect(int api);
115     virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
116     virtual void allocateBuffers(bool async, uint32_t width, uint32_t height,
117             uint32_t format, uint32_t usage);
118 
119     //
120     // Utility methods
121     //
122     static Source fbSourceForCompositionType(CompositionType type);
123     status_t dequeueBuffer(Source source, uint32_t format, uint32_t usage,
124             int* sslot, sp<Fence>* fence);
125     void updateQueueBufferOutput(const QueueBufferOutput& qbo);
126     void resetPerFrameState();
127     status_t refreshOutputBuffer();
128 
129     // Both the sink and scratch buffer pools have their own set of slots
130     // ("source slots", or "sslot"). We have to merge these into the single
131     // set of slots used by the GLES producer ("producer slots" or "pslot") and
132     // internally in the VirtualDisplaySurface. To minimize the number of times
133     // a producer slot switches which source it comes from, we map source slot
134     // numbers to producer slot numbers differently for each source.
135     static int mapSource2ProducerSlot(Source source, int sslot);
136     static int mapProducer2SourceSlot(Source source, int pslot);
137 
138     //
139     // Immutable after construction
140     //
141     HWComposer& mHwc;
142     const int32_t mDisplayId;
143     const String8 mDisplayName;
144     sp<IGraphicBufferProducer> mSource[2]; // indexed by SOURCE_*
145     uint32_t mDefaultOutputFormat;
146 
147     //
148     // Inter-frame state
149     //
150 
151     // To avoid buffer reallocations, we track the buffer usage and format
152     // we used on the previous frame and use it again on the new frame. If
153     // the composition type changes or the GLES driver starts requesting
154     // different usage/format, we'll get a new buffer.
155     uint32_t mOutputFormat;
156     uint32_t mOutputUsage;
157 
158     // Since we present a single producer interface to the GLES driver, but
159     // are internally muxing between the sink and scratch producers, we have
160     // to keep track of which source last returned each producer slot from
161     // dequeueBuffer. Each bit in mProducerSlotSource corresponds to a producer
162     // slot. Both mProducerSlotSource and mProducerBuffers are indexed by a
163     // "producer slot"; see the mapSlot*() functions.
164     uint64_t mProducerSlotSource;
165     sp<GraphicBuffer> mProducerBuffers[BufferQueue::NUM_BUFFER_SLOTS];
166 
167     // The QueueBufferOutput with the latest info from the sink, and with the
168     // transform hint cleared. Since we defer queueBuffer from the GLES driver
169     // to the sink, we have to return the previous version.
170     QueueBufferOutput mQueueBufferOutput;
171 
172     // Details of the current sink buffer. These become valid when a buffer is
173     // dequeued from the sink, and are used when queueing the buffer.
174     uint32_t mSinkBufferWidth, mSinkBufferHeight;
175 
176     //
177     // Intra-frame state
178     //
179 
180     // Composition type and GLES buffer source for the current frame.
181     // Valid after prepareFrame(), cleared in onFrameCommitted.
182     CompositionType mCompositionType;
183 
184     // mFbFence is the fence HWC should wait for before reading the framebuffer
185     // target buffer.
186     sp<Fence> mFbFence;
187 
188     // mOutputFence is the fence HWC should wait for before writing to the
189     // output buffer.
190     sp<Fence> mOutputFence;
191 
192     // Producer slot numbers for the buffers to use for HWC framebuffer target
193     // and output.
194     int mFbProducerSlot;
195     int mOutputProducerSlot;
196 
197     // Debug only -- track the sequence of events in each frame so we can make
198     // sure they happen in the order we expect. This class implicitly models
199     // a state machine; this enum/variable makes it explicit.
200     //
201     // +-----------+-------------------+-------------+
202     // | State     | Event             || Next State |
203     // +-----------+-------------------+-------------+
204     // | IDLE      | beginFrame        || BEGUN      |
205     // | BEGUN     | prepareFrame      || PREPARED   |
206     // | PREPARED  | dequeueBuffer [1] || GLES       |
207     // | PREPARED  | advanceFrame [2]  || HWC        |
208     // | GLES      | queueBuffer       || GLES_DONE  |
209     // | GLES_DONE | advanceFrame      || HWC        |
210     // | HWC       | onFrameCommitted  || IDLE       |
211     // +-----------+-------------------++------------+
212     // [1] COMPOSITION_GLES and COMPOSITION_MIXED frames.
213     // [2] COMPOSITION_HWC frames.
214     //
215     enum DbgState {
216         // no buffer dequeued, don't know anything about the next frame
217         DBG_STATE_IDLE,
218         // output buffer dequeued, framebuffer source not yet known
219         DBG_STATE_BEGUN,
220         // output buffer dequeued, framebuffer source known but not provided
221         // to GLES yet.
222         DBG_STATE_PREPARED,
223         // GLES driver has a buffer dequeued
224         DBG_STATE_GLES,
225         // GLES driver has queued the buffer, we haven't sent it to HWC yet
226         DBG_STATE_GLES_DONE,
227         // HWC has the buffer for this frame
228         DBG_STATE_HWC,
229     };
230     DbgState mDbgState;
231     CompositionType mDbgLastCompositionType;
232 
233     const char* dbgStateStr() const;
234     static const char* dbgSourceStr(Source s);
235 
236     bool mMustRecompose;
237 };
238 
239 // ---------------------------------------------------------------------------
240 } // namespace android
241 // ---------------------------------------------------------------------------
242 
243 #endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
244 
245