VirtualDisplaySurface.h revision 583b1b32191992d6ada58b3c61c71932a71c0c4b 
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;
30class 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 */
71class VirtualDisplaySurface : public DisplaySurface,
72                              public BnGraphicBufferProducer,
73                              private ConsumerBase {
74public:
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 dumpAsString(String8& result) const;
90    virtual void resizeBuffers(const uint32_t w, const uint32_t h);
91
92private:
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 setMaxDequeuedBufferCount(int maxDequeuedBuffers);
102    virtual status_t setAsyncMode(bool async);
103    virtual status_t dequeueBuffer(int* pslot, sp<Fence>* fence, bool async,
104            uint32_t w, uint32_t h, PixelFormat format, uint32_t usage);
105    virtual status_t detachBuffer(int slot);
106    virtual status_t detachNextBuffer(sp<GraphicBuffer>* outBuffer,
107            sp<Fence>* outFence);
108    virtual status_t attachBuffer(int* slot, const sp<GraphicBuffer>& buffer);
109    virtual status_t queueBuffer(int pslot,
110            const QueueBufferInput& input, QueueBufferOutput* output);
111    virtual status_t cancelBuffer(int pslot, const sp<Fence>& fence);
112    virtual int query(int what, int* value);
113    virtual status_t connect(const sp<IProducerListener>& listener,
114            int api, bool producerControlledByApp, QueueBufferOutput* output);
115    virtual status_t disconnect(int api);
116    virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
117    virtual void allocateBuffers(bool async, uint32_t width, uint32_t height,
118            PixelFormat format, uint32_t usage);
119    virtual status_t allowAllocation(bool allow);
120    virtual status_t setGenerationNumber(uint32_t generationNumber);
121    virtual String8 getConsumerName() const override;
122
123    //
124    // Utility methods
125    //
126    static Source fbSourceForCompositionType(CompositionType type);
127    status_t dequeueBuffer(Source source, PixelFormat format, uint32_t usage,
128            int* sslot, sp<Fence>* fence);
129    void updateQueueBufferOutput(const QueueBufferOutput& qbo);
130    void resetPerFrameState();
131    status_t refreshOutputBuffer();
132
133    // Both the sink and scratch buffer pools have their own set of slots
134    // ("source slots", or "sslot"). We have to merge these into the single
135    // set of slots used by the GLES producer ("producer slots" or "pslot") and
136    // internally in the VirtualDisplaySurface. To minimize the number of times
137    // a producer slot switches which source it comes from, we map source slot
138    // numbers to producer slot numbers differently for each source.
139    static int mapSource2ProducerSlot(Source source, int sslot);
140    static int mapProducer2SourceSlot(Source source, int pslot);
141
142    //
143    // Immutable after construction
144    //
145    HWComposer& mHwc;
146    const int32_t mDisplayId;
147    const String8 mDisplayName;
148    sp<IGraphicBufferProducer> mSource[2]; // indexed by SOURCE_*
149    uint32_t mDefaultOutputFormat;
150
151    //
152    // Inter-frame state
153    //
154
155    // To avoid buffer reallocations, we track the buffer usage and format
156    // we used on the previous frame and use it again on the new frame. If
157    // the composition type changes or the GLES driver starts requesting
158    // different usage/format, we'll get a new buffer.
159    uint32_t mOutputFormat;
160    uint32_t mOutputUsage;
161
162    // Since we present a single producer interface to the GLES driver, but
163    // are internally muxing between the sink and scratch producers, we have
164    // to keep track of which source last returned each producer slot from
165    // dequeueBuffer. Each bit in mProducerSlotSource corresponds to a producer
166    // slot. Both mProducerSlotSource and mProducerBuffers are indexed by a
167    // "producer slot"; see the mapSlot*() functions.
168    uint64_t mProducerSlotSource;
169    sp<GraphicBuffer> mProducerBuffers[BufferQueue::NUM_BUFFER_SLOTS];
170
171    // The QueueBufferOutput with the latest info from the sink, and with the
172    // transform hint cleared. Since we defer queueBuffer from the GLES driver
173    // to the sink, we have to return the previous version.
174    QueueBufferOutput mQueueBufferOutput;
175
176    // Details of the current sink buffer. These become valid when a buffer is
177    // dequeued from the sink, and are used when queueing the buffer.
178    uint32_t mSinkBufferWidth, mSinkBufferHeight;
179
180    //
181    // Intra-frame state
182    //
183
184    // Composition type and GLES buffer source for the current frame.
185    // Valid after prepareFrame(), cleared in onFrameCommitted.
186    CompositionType mCompositionType;
187
188    // mFbFence is the fence HWC should wait for before reading the framebuffer
189    // target buffer.
190    sp<Fence> mFbFence;
191
192    // mOutputFence is the fence HWC should wait for before writing to the
193    // output buffer.
194    sp<Fence> mOutputFence;
195
196    // Producer slot numbers for the buffers to use for HWC framebuffer target
197    // and output.
198    int mFbProducerSlot;
199    int mOutputProducerSlot;
200
201    // Debug only -- track the sequence of events in each frame so we can make
202    // sure they happen in the order we expect. This class implicitly models
203    // a state machine; this enum/variable makes it explicit.
204    //
205    // +-----------+-------------------+-------------+
206    // | State     | Event             || Next State |
207    // +-----------+-------------------+-------------+
208    // | IDLE      | beginFrame        || BEGUN      |
209    // | BEGUN     | prepareFrame      || PREPARED   |
210    // | PREPARED  | dequeueBuffer [1] || GLES       |
211    // | PREPARED  | advanceFrame [2]  || HWC        |
212    // | GLES      | queueBuffer       || GLES_DONE  |
213    // | GLES_DONE | advanceFrame      || HWC        |
214    // | HWC       | onFrameCommitted  || IDLE       |
215    // +-----------+-------------------++------------+
216    // [1] COMPOSITION_GLES and COMPOSITION_MIXED frames.
217    // [2] COMPOSITION_HWC frames.
218    //
219    enum DbgState {
220        // no buffer dequeued, don't know anything about the next frame
221        DBG_STATE_IDLE,
222        // output buffer dequeued, framebuffer source not yet known
223        DBG_STATE_BEGUN,
224        // output buffer dequeued, framebuffer source known but not provided
225        // to GLES yet.
226        DBG_STATE_PREPARED,
227        // GLES driver has a buffer dequeued
228        DBG_STATE_GLES,
229        // GLES driver has queued the buffer, we haven't sent it to HWC yet
230        DBG_STATE_GLES_DONE,
231        // HWC has the buffer for this frame
232        DBG_STATE_HWC,
233    };
234    DbgState mDbgState;
235    CompositionType mDbgLastCompositionType;
236
237    const char* dbgStateStr() const;
238    static const char* dbgSourceStr(Source s);
239
240    bool mMustRecompose;
241};
242
243// ---------------------------------------------------------------------------
244} // namespace android
245// ---------------------------------------------------------------------------
246
247#endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
248
249