VirtualDisplaySurface.h revision b9b088375d33a87b201cdbe18be71802e2607717 
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// ---------------------------------------------------------------------------
26namespace android {
27// ---------------------------------------------------------------------------
28
29class HWComposer;
30
31/* This DisplaySurface implementation supports virtual displays, where GLES
32 * and/or HWC compose into a buffer that is then passed to an arbitrary
33 * consumer (the sink) running in another process.
34 *
35 * The simplest case is when the virtual display will never use the h/w
36 * composer -- either the h/w composer doesn't support writing to buffers, or
37 * there are more virtual displays than it supports simultaneously. In this
38 * case, the GLES driver works directly with the output buffer queue, and
39 * calls to the VirtualDisplay from SurfaceFlinger and DisplayHardware do
40 * nothing.
41 *
42 * If h/w composer might be used, then each frame will fall into one of three
43 * configurations: GLES-only, HWC-only, and MIXED composition. In all of these,
44 * we must provide a FB target buffer and output buffer for the HWC set() call.
45 *
46 * In GLES-only composition, the GLES driver is given a buffer from the sink to
47 * render into. When the GLES driver queues the buffer to the
48 * VirtualDisplaySurface, the VirtualDisplaySurface holds onto it instead of
49 * immediately queueing it to the sink. The buffer is used as both the FB
50 * target and output buffer for HWC, though on these frames the HWC doesn't
51 * do any work for this display and doesn't write to the output buffer. After
52 * composition is complete, the buffer is queued to the sink.
53 *
54 * In HWC-only composition, the VirtualDisplaySurface dequeues a buffer from
55 * the sink and passes it to HWC as both the FB target buffer and output
56 * buffer. The HWC doesn't need to read from the FB target buffer, but does
57 * write to the output buffer. After composition is complete, the buffer is
58 * queued to the sink.
59 *
60 * On MIXED frames, things become more complicated, since some h/w composer
61 * implementations can't read from and write to the same buffer. This class has
62 * an internal BufferQueue that it uses as a scratch buffer pool. The GLES
63 * driver is given a scratch buffer to render into. When it finishes rendering,
64 * the buffer is queued and then immediately acquired by the
65 * VirtualDisplaySurface. The scratch buffer is then used as the FB target
66 * buffer for HWC, and a separate buffer is dequeued from the sink and used as
67 * the HWC output buffer. When HWC composition is complete, the scratch buffer
68 * is released and the output buffer is queued to the sink.
69 */
70class VirtualDisplaySurface : public DisplaySurface,
71                              public BnGraphicBufferProducer,
72                              private ConsumerBase {
73public:
74    VirtualDisplaySurface(HWComposer& hwc, int32_t dispId,
75            const sp<IGraphicBufferProducer>& sink,
76            const sp<IGraphicBufferProducer>& bqProducer,
77            const sp<IGraphicBufferConsumer>& bqConsumer,
78            const String8& name);
79
80    //
81    // DisplaySurface interface
82    //
83    virtual status_t beginFrame(bool mustRecompose);
84    virtual status_t prepareFrame(CompositionType compositionType);
85    virtual status_t compositionComplete();
86    virtual status_t advanceFrame();
87    virtual void onFrameCommitted();
88    virtual void dump(String8& result) const;
89
90private:
91    enum Source {SOURCE_SINK = 0, SOURCE_SCRATCH = 1};
92
93    virtual ~VirtualDisplaySurface();
94
95    //
96    // IGraphicBufferProducer interface, used by the GLES driver.
97    //
98    virtual status_t requestBuffer(int pslot, sp<GraphicBuffer>* outBuf);
99    virtual status_t setBufferCount(int bufferCount);
100    virtual status_t dequeueBuffer(int* pslot, sp<Fence>* fence, bool async,
101            uint32_t w, uint32_t h, uint32_t format, uint32_t usage);
102    virtual status_t detachBuffer(int slot);
103    virtual status_t attachBuffer(int* slot, const sp<GraphicBuffer>& buffer);
104    virtual status_t queueBuffer(int pslot,
105            const QueueBufferInput& input, QueueBufferOutput* output);
106    virtual void cancelBuffer(int pslot, const sp<Fence>& fence);
107    virtual int query(int what, int* value);
108    virtual status_t connect(const sp<IBinder>& token,
109            int api, bool producerControlledByApp, QueueBufferOutput* output);
110    virtual status_t disconnect(int api);
111    virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
112
113    //
114    // Utility methods
115    //
116    static Source fbSourceForCompositionType(CompositionType type);
117    status_t dequeueBuffer(Source source, uint32_t format, uint32_t usage,
118            int* sslot, sp<Fence>* fence);
119    void updateQueueBufferOutput(const QueueBufferOutput& qbo);
120    void resetPerFrameState();
121    status_t refreshOutputBuffer();
122
123    // Both the sink and scratch buffer pools have their own set of slots
124    // ("source slots", or "sslot"). We have to merge these into the single
125    // set of slots used by the GLES producer ("producer slots" or "pslot") and
126    // internally in the VirtualDisplaySurface. To minimize the number of times
127    // a producer slot switches which source it comes from, we map source slot
128    // numbers to producer slot numbers differently for each source.
129    static int mapSource2ProducerSlot(Source source, int sslot);
130    static int mapProducer2SourceSlot(Source source, int pslot);
131
132    //
133    // Immutable after construction
134    //
135    HWComposer& mHwc;
136    const int32_t mDisplayId;
137    const String8 mDisplayName;
138    sp<IGraphicBufferProducer> mSource[2]; // indexed by SOURCE_*
139    uint32_t mDefaultOutputFormat;
140
141    //
142    // Inter-frame state
143    //
144
145    // To avoid buffer reallocations, we track the buffer usage and format
146    // we used on the previous frame and use it again on the new frame. If
147    // the composition type changes or the GLES driver starts requesting
148    // different usage/format, we'll get a new buffer.
149    uint32_t mOutputFormat;
150    uint32_t mOutputUsage;
151
152    // Since we present a single producer interface to the GLES driver, but
153    // are internally muxing between the sink and scratch producers, we have
154    // to keep track of which source last returned each producer slot from
155    // dequeueBuffer. Each bit in mLastSlotSource corresponds to a producer
156    // slot. Both mProducerSlotSource and mProducerBuffers are indexed by a
157    // "producer slot"; see the mapSlot*() functions.
158    uint32_t mProducerSlotSource;
159    sp<GraphicBuffer> mProducerBuffers[BufferQueue::NUM_BUFFER_SLOTS];
160
161    // The QueueBufferOutput with the latest info from the sink, and with the
162    // transform hint cleared. Since we defer queueBuffer from the GLES driver
163    // to the sink, we have to return the previous version.
164    QueueBufferOutput mQueueBufferOutput;
165
166    //
167    // Intra-frame state
168    //
169
170    // Composition type and GLES buffer source for the current frame.
171    // Valid after prepareFrame(), cleared in onFrameCommitted.
172    CompositionType mCompositionType;
173
174    // Details of the current sink buffer. These become valid when a buffer is
175    // dequeued from the sink, and are used when queueing the buffer.
176    uint32_t mSinkBufferWidth, mSinkBufferHeight;
177
178    // mFbFence is the fence HWC should wait for before reading the framebuffer
179    // target buffer.
180    sp<Fence> mFbFence;
181
182    // mOutputFence is the fence HWC should wait for before writing to the
183    // output buffer.
184    sp<Fence> mOutputFence;
185
186    // Producer slot numbers for the buffers to use for HWC framebuffer target
187    // and output.
188    int mFbProducerSlot;
189    int mOutputProducerSlot;
190
191    // Debug only -- track the sequence of events in each frame so we can make
192    // sure they happen in the order we expect. This class implicitly models
193    // a state machine; this enum/variable makes it explicit.
194    //
195    // +-----------+-------------------+-------------+
196    // | State     | Event             || Next State |
197    // +-----------+-------------------+-------------+
198    // | IDLE      | beginFrame        || BEGUN      |
199    // | BEGUN     | prepareFrame      || PREPARED   |
200    // | PREPARED  | dequeueBuffer [1] || GLES       |
201    // | PREPARED  | advanceFrame [2]  || HWC        |
202    // | GLES      | queueBuffer       || GLES_DONE  |
203    // | GLES_DONE | advanceFrame      || HWC        |
204    // | HWC       | onFrameCommitted  || IDLE       |
205    // +-----------+-------------------++------------+
206    // [1] COMPOSITION_GLES and COMPOSITION_MIXED frames.
207    // [2] COMPOSITION_HWC frames.
208    //
209    enum DbgState {
210        // no buffer dequeued, don't know anything about the next frame
211        DBG_STATE_IDLE,
212        // output buffer dequeued, framebuffer source not yet known
213        DBG_STATE_BEGUN,
214        // output buffer dequeued, framebuffer source known but not provided
215        // to GLES yet.
216        DBG_STATE_PREPARED,
217        // GLES driver has a buffer dequeued
218        DBG_STATE_GLES,
219        // GLES driver has queued the buffer, we haven't sent it to HWC yet
220        DBG_STATE_GLES_DONE,
221        // HWC has the buffer for this frame
222        DBG_STATE_HWC,
223    };
224    DbgState mDbgState;
225    CompositionType mDbgLastCompositionType;
226
227    const char* dbgStateStr() const;
228    static const char* dbgSourceStr(Source s);
229
230    bool mMustRecompose;
231};
232
233// ---------------------------------------------------------------------------
234} // namespace android
235// ---------------------------------------------------------------------------
236
237#endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
238
239