VirtualDisplaySurface.h revision c6f30bdee1f634eb90d68cb76efe935b6535a1e8 
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 setBufferCount(int bufferCount);
102    virtual status_t dequeueBuffer(int* pslot, sp<Fence>* fence, bool async,
103            uint32_t w, uint32_t h, PixelFormat 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            PixelFormat format, uint32_t usage);
118    virtual status_t allowAllocation(bool allow);
119    virtual status_t setGenerationNumber(uint32_t generationNumber);
120    virtual String8 getConsumerName() const override;
121
122    //
123    // Utility methods
124    //
125    static Source fbSourceForCompositionType(CompositionType type);
126    status_t dequeueBuffer(Source source, PixelFormat format, uint32_t usage,
127            int* sslot, sp<Fence>* fence);
128    void updateQueueBufferOutput(const QueueBufferOutput& qbo);
129    void resetPerFrameState();
130    status_t refreshOutputBuffer();
131
132    // Both the sink and scratch buffer pools have their own set of slots
133    // ("source slots", or "sslot"). We have to merge these into the single
134    // set of slots used by the GLES producer ("producer slots" or "pslot") and
135    // internally in the VirtualDisplaySurface. To minimize the number of times
136    // a producer slot switches which source it comes from, we map source slot
137    // numbers to producer slot numbers differently for each source.
138    static int mapSource2ProducerSlot(Source source, int sslot);
139    static int mapProducer2SourceSlot(Source source, int pslot);
140
141    //
142    // Immutable after construction
143    //
144    HWComposer& mHwc;
145    const int32_t mDisplayId;
146    const String8 mDisplayName;
147    sp<IGraphicBufferProducer> mSource[2]; // indexed by SOURCE_*
148    uint32_t mDefaultOutputFormat;
149
150    //
151    // Inter-frame state
152    //
153
154    // To avoid buffer reallocations, we track the buffer usage and format
155    // we used on the previous frame and use it again on the new frame. If
156    // the composition type changes or the GLES driver starts requesting
157    // different usage/format, we'll get a new buffer.
158    uint32_t mOutputFormat;
159    uint32_t mOutputUsage;
160
161    // Since we present a single producer interface to the GLES driver, but
162    // are internally muxing between the sink and scratch producers, we have
163    // to keep track of which source last returned each producer slot from
164    // dequeueBuffer. Each bit in mProducerSlotSource corresponds to a producer
165    // slot. Both mProducerSlotSource and mProducerBuffers are indexed by a
166    // "producer slot"; see the mapSlot*() functions.
167    uint64_t mProducerSlotSource;
168    sp<GraphicBuffer> mProducerBuffers[BufferQueue::NUM_BUFFER_SLOTS];
169
170    // The QueueBufferOutput with the latest info from the sink, and with the
171    // transform hint cleared. Since we defer queueBuffer from the GLES driver
172    // to the sink, we have to return the previous version.
173    QueueBufferOutput mQueueBufferOutput;
174
175    // Details of the current sink buffer. These become valid when a buffer is
176    // dequeued from the sink, and are used when queueing the buffer.
177    uint32_t mSinkBufferWidth, mSinkBufferHeight;
178
179    //
180    // Intra-frame state
181    //
182
183    // Composition type and GLES buffer source for the current frame.
184    // Valid after prepareFrame(), cleared in onFrameCommitted.
185    CompositionType mCompositionType;
186
187    // mFbFence is the fence HWC should wait for before reading the framebuffer
188    // target buffer.
189    sp<Fence> mFbFence;
190
191    // mOutputFence is the fence HWC should wait for before writing to the
192    // output buffer.
193    sp<Fence> mOutputFence;
194
195    // Producer slot numbers for the buffers to use for HWC framebuffer target
196    // and output.
197    int mFbProducerSlot;
198    int mOutputProducerSlot;
199
200    // Debug only -- track the sequence of events in each frame so we can make
201    // sure they happen in the order we expect. This class implicitly models
202    // a state machine; this enum/variable makes it explicit.
203    //
204    // +-----------+-------------------+-------------+
205    // | State     | Event             || Next State |
206    // +-----------+-------------------+-------------+
207    // | IDLE      | beginFrame        || BEGUN      |
208    // | BEGUN     | prepareFrame      || PREPARED   |
209    // | PREPARED  | dequeueBuffer [1] || GLES       |
210    // | PREPARED  | advanceFrame [2]  || HWC        |
211    // | GLES      | queueBuffer       || GLES_DONE  |
212    // | GLES_DONE | advanceFrame      || HWC        |
213    // | HWC       | onFrameCommitted  || IDLE       |
214    // +-----------+-------------------++------------+
215    // [1] COMPOSITION_GLES and COMPOSITION_MIXED frames.
216    // [2] COMPOSITION_HWC frames.
217    //
218    enum DbgState {
219        // no buffer dequeued, don't know anything about the next frame
220        DBG_STATE_IDLE,
221        // output buffer dequeued, framebuffer source not yet known
222        DBG_STATE_BEGUN,
223        // output buffer dequeued, framebuffer source known but not provided
224        // to GLES yet.
225        DBG_STATE_PREPARED,
226        // GLES driver has a buffer dequeued
227        DBG_STATE_GLES,
228        // GLES driver has queued the buffer, we haven't sent it to HWC yet
229        DBG_STATE_GLES_DONE,
230        // HWC has the buffer for this frame
231        DBG_STATE_HWC,
232    };
233    DbgState mDbgState;
234    CompositionType mDbgLastCompositionType;
235
236    const char* dbgStateStr() const;
237    static const char* dbgSourceStr(Source s);
238
239    bool mMustRecompose;
240};
241
242// ---------------------------------------------------------------------------
243} // namespace android
244// ---------------------------------------------------------------------------
245
246#endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
247
248