CpuConsumer.h revision e41b318bc4708e1dee9364e73215ff0d51fb76a1 
1/*
2 * Copyright (C) 2012 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_GUI_CPUCONSUMER_H
18#define ANDROID_GUI_CPUCONSUMER_H
19
20#include <gui/BufferQueue.h>
21
22#include <ui/GraphicBuffer.h>
23
24#include <utils/String8.h>
25#include <utils/Vector.h>
26#include <utils/threads.h>
27
28#define ANDROID_GRAPHICS_CPUCONSUMER_JNI_ID "mCpuConsumer"
29
30namespace android {
31
32/**
33 * CpuConsumer is a BufferQueue consumer endpoint that allows direct CPU
34 * access to the underlying gralloc buffers provided by BufferQueue. Multiple
35 * buffers may be acquired by it at once, to be used concurrently by the
36 * CpuConsumer owner. Sets gralloc usage flags to be software-read-only.
37 * This queue is synchronous by default.
38 */
39
40class CpuConsumer: public virtual RefBase,
41                     protected BufferQueue::ConsumerListener
42{
43  public:
44    struct FrameAvailableListener : public virtual RefBase {
45        // onFrameAvailable() is called each time an additional frame becomes
46        // available for consumption. A new frame queued will always trigger the
47        // callback, whether the queue is empty or not.
48        //
49        // This is called without any lock held and can be called concurrently
50        // by multiple threads.
51        virtual void onFrameAvailable() = 0;
52    };
53
54    struct LockedBuffer {
55        uint8_t    *data;
56        uint32_t    width;
57        uint32_t    height;
58        PixelFormat format;
59        uint32_t    stride;
60        Rect        crop;
61        uint32_t    transform;
62        uint32_t    scalingMode;
63        int64_t     timestamp;
64        uint64_t    frameNumber;
65    };
66
67    // Create a new CPU consumer. The maxLockedBuffers parameter specifies
68    // how many buffers can be locked for user access at the same time.
69    CpuConsumer(uint32_t maxLockedBuffers);
70
71    virtual ~CpuConsumer();
72
73    // set the name of the CpuConsumer that will be used to identify it in
74    // log messages.
75    void setName(const String8& name);
76
77    // Gets the next graphics buffer from the producer and locks it for CPU use,
78    // filling out the passed-in locked buffer structure with the native pointer
79    // and metadata. Returns BAD_VALUE if no new buffer is available, and
80    // INVALID_OPERATION if the maximum number of buffers is already locked.
81    //
82    // Only a fixed number of buffers can be locked at a time, determined by the
83    // construction-time maxLockedBuffers parameter. If INVALID_OPERATION is
84    // returned by lockNextBuffer, then old buffers must be returned to the queue
85    // by calling unlockBuffer before more buffers can be acquired.
86    status_t lockNextBuffer(LockedBuffer *nativeBuffer);
87
88    // Returns a locked buffer to the queue, allowing it to be reused. Since
89    // only a fixed number of buffers may be locked at a time, old buffers must
90    // be released by calling unlockBuffer to ensure new buffers can be acquired by
91    // lockNextBuffer.
92    status_t unlockBuffer(const LockedBuffer &nativeBuffer);
93
94    // setFrameAvailableListener sets the listener object that will be notified
95    // when a new frame becomes available.
96    void setFrameAvailableListener(const sp<FrameAvailableListener>& listener);
97
98    sp<ISurfaceTexture> getProducerInterface() const { return mBufferQueue; }
99  protected:
100
101    // Implementation of the BufferQueue::ConsumerListener interface.  These
102    // calls are used to notify the CpuConsumer of asynchronous events in the
103    // BufferQueue.
104    virtual void onFrameAvailable();
105    virtual void onBuffersReleased();
106
107  private:
108    // Free local buffer state
109    status_t freeBufferLocked(int buf);
110
111    // Maximum number of buffers that can be locked at a time
112    uint32_t mMaxLockedBuffers;
113
114    // mName is a string used to identify the SurfaceTexture in log messages.
115    // It can be set by the setName method.
116    String8 mName;
117
118    // mFrameAvailableListener is the listener object that will be called when a
119    // new frame becomes available. If it is not NULL it will be called from
120    // queueBuffer.
121    sp<FrameAvailableListener> mFrameAvailableListener;
122
123    // Underlying buffer queue
124    sp<BufferQueue> mBufferQueue;
125
126    // Array for caching buffers from the buffer queue
127    sp<GraphicBuffer> mBufferSlot[BufferQueue::NUM_BUFFER_SLOTS];
128    // Array for tracking pointers passed to the consumer, matching the
129    // mBufferSlot indexing
130    void *mBufferPointers[BufferQueue::NUM_BUFFER_SLOTS];
131    // Count of currently locked buffers
132    uint32_t mCurrentLockedBuffers;
133
134    // mMutex is the mutex used to prevent concurrent access to the member
135    // variables of CpuConsumer objects. It must be locked whenever the
136    // member variables are accessed.
137    mutable Mutex mMutex;
138};
139
140} // namespace android
141
142#endif // ANDROID_GUI_CPUCONSUMER_H
143