VirtualDisplaySurface.h revision 89fd4f7fa6bd17ce5400979c3b9e5ba0bf7e919e 
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    using BBinder::dump;
90    virtual void dump(String8& result) const;
91    virtual void resizeBuffers(const uint32_t w, const uint32_t h);
92
93private:
94    enum Source {SOURCE_SINK = 0, SOURCE_SCRATCH = 1};
95
96    virtual ~VirtualDisplaySurface();
97
98    //
99    // IGraphicBufferProducer interface, used by the GLES driver.
100    //
101    virtual status_t requestBuffer(int pslot, sp<GraphicBuffer>* outBuf);
102    virtual status_t setBufferCount(int bufferCount);
103    virtual status_t dequeueBuffer(int* pslot, sp<Fence>* fence, bool async,
104            uint32_t w, uint32_t h, uint32_t 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 void 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            uint32_t format, uint32_t usage);
119
120    //
121    // Utility methods
122    //
123    static Source fbSourceForCompositionType(CompositionType type);
124    status_t dequeueBuffer(Source source, uint32_t format, uint32_t usage,
125            int* sslot, sp<Fence>* fence);
126    void updateQueueBufferOutput(const QueueBufferOutput& qbo);
127    void resetPerFrameState();
128    status_t refreshOutputBuffer();
129
130    // Both the sink and scratch buffer pools have their own set of slots
131    // ("source slots", or "sslot"). We have to merge these into the single
132    // set of slots used by the GLES producer ("producer slots" or "pslot") and
133    // internally in the VirtualDisplaySurface. To minimize the number of times
134    // a producer slot switches which source it comes from, we map source slot
135    // numbers to producer slot numbers differently for each source.
136    static int mapSource2ProducerSlot(Source source, int sslot);
137    static int mapProducer2SourceSlot(Source source, int pslot);
138
139    //
140    // Immutable after construction
141    //
142    HWComposer& mHwc;
143    const int32_t mDisplayId;
144    const String8 mDisplayName;
145    sp<IGraphicBufferProducer> mSource[2]; // indexed by SOURCE_*
146    uint32_t mDefaultOutputFormat;
147
148    //
149    // Inter-frame state
150    //
151
152    // To avoid buffer reallocations, we track the buffer usage and format
153    // we used on the previous frame and use it again on the new frame. If
154    // the composition type changes or the GLES driver starts requesting
155    // different usage/format, we'll get a new buffer.
156    uint32_t mOutputFormat;
157    uint32_t mOutputUsage;
158
159    // Since we present a single producer interface to the GLES driver, but
160    // are internally muxing between the sink and scratch producers, we have
161    // to keep track of which source last returned each producer slot from
162    // dequeueBuffer. Each bit in mProducerSlotSource corresponds to a producer
163    // slot. Both mProducerSlotSource and mProducerBuffers are indexed by a
164    // "producer slot"; see the mapSlot*() functions.
165    uint64_t mProducerSlotSource;
166    sp<GraphicBuffer> mProducerBuffers[BufferQueue::NUM_BUFFER_SLOTS];
167
168    // The QueueBufferOutput with the latest info from the sink, and with the
169    // transform hint cleared. Since we defer queueBuffer from the GLES driver
170    // to the sink, we have to return the previous version.
171    QueueBufferOutput mQueueBufferOutput;
172
173    // Details of the current sink buffer. These become valid when a buffer is
174    // dequeued from the sink, and are used when queueing the buffer.
175    uint32_t mSinkBufferWidth, mSinkBufferHeight;
176
177    //
178    // Intra-frame state
179    //
180
181    // Composition type and GLES buffer source for the current frame.
182    // Valid after prepareFrame(), cleared in onFrameCommitted.
183    CompositionType mCompositionType;
184
185    // mFbFence is the fence HWC should wait for before reading the framebuffer
186    // target buffer.
187    sp<Fence> mFbFence;
188
189    // mOutputFence is the fence HWC should wait for before writing to the
190    // output buffer.
191    sp<Fence> mOutputFence;
192
193    // Producer slot numbers for the buffers to use for HWC framebuffer target
194    // and output.
195    int mFbProducerSlot;
196    int mOutputProducerSlot;
197
198    // Debug only -- track the sequence of events in each frame so we can make
199    // sure they happen in the order we expect. This class implicitly models
200    // a state machine; this enum/variable makes it explicit.
201    //
202    // +-----------+-------------------+-------------+
203    // | State     | Event             || Next State |
204    // +-----------+-------------------+-------------+
205    // | IDLE      | beginFrame        || BEGUN      |
206    // | BEGUN     | prepareFrame      || PREPARED   |
207    // | PREPARED  | dequeueBuffer [1] || GLES       |
208    // | PREPARED  | advanceFrame [2]  || HWC        |
209    // | GLES      | queueBuffer       || GLES_DONE  |
210    // | GLES_DONE | advanceFrame      || HWC        |
211    // | HWC       | onFrameCommitted  || IDLE       |
212    // +-----------+-------------------++------------+
213    // [1] COMPOSITION_GLES and COMPOSITION_MIXED frames.
214    // [2] COMPOSITION_HWC frames.
215    //
216    enum DbgState {
217        // no buffer dequeued, don't know anything about the next frame
218        DBG_STATE_IDLE,
219        // output buffer dequeued, framebuffer source not yet known
220        DBG_STATE_BEGUN,
221        // output buffer dequeued, framebuffer source known but not provided
222        // to GLES yet.
223        DBG_STATE_PREPARED,
224        // GLES driver has a buffer dequeued
225        DBG_STATE_GLES,
226        // GLES driver has queued the buffer, we haven't sent it to HWC yet
227        DBG_STATE_GLES_DONE,
228        // HWC has the buffer for this frame
229        DBG_STATE_HWC,
230    };
231    DbgState mDbgState;
232    CompositionType mDbgLastCompositionType;
233
234    const char* dbgStateStr() const;
235    static const char* dbgSourceStr(Source s);
236
237    bool mMustRecompose;
238};
239
240// ---------------------------------------------------------------------------
241} // namespace android
242// ---------------------------------------------------------------------------
243
244#endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
245
246