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      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_BUFFERQUEUE_H
     18 #define ANDROID_GUI_BUFFERQUEUE_H
     19 
     20 #include <gui/BufferItem.h>
     21 #include <gui/BufferQueueDefs.h>
     22 #include <gui/IGraphicBufferConsumer.h>
     23 #include <gui/IGraphicBufferProducer.h>
     24 #include <gui/IConsumerListener.h>
     25 
     26 namespace android {
     27 
     28 class BufferQueue {
     29 public:
     30     // BufferQueue will keep track of at most this value of buffers.
     31     // Attempts at runtime to increase the number of buffers past this will fail.
     32     enum { NUM_BUFFER_SLOTS = BufferQueueDefs::NUM_BUFFER_SLOTS };
     33     // Used as a placeholder slot# when the value isn't pointing to an existing buffer.
     34     enum { INVALID_BUFFER_SLOT = BufferItem::INVALID_BUFFER_SLOT };
     35     // Alias to <IGraphicBufferConsumer.h> -- please scope from there in future code!
     36     enum {
     37         NO_BUFFER_AVAILABLE = IGraphicBufferConsumer::NO_BUFFER_AVAILABLE,
     38         PRESENT_LATER = IGraphicBufferConsumer::PRESENT_LATER,
     39     };
     40 
     41     // When in async mode we reserve two slots in order to guarantee that the
     42     // producer and consumer can run asynchronously.
     43     enum { MAX_MAX_ACQUIRED_BUFFERS = NUM_BUFFER_SLOTS - 2 };
     44 
     45     // for backward source compatibility
     46     typedef ::android::ConsumerListener ConsumerListener;
     47 
     48     // ProxyConsumerListener is a ConsumerListener implementation that keeps a weak
     49     // reference to the actual consumer object.  It forwards all calls to that
     50     // consumer object so long as it exists.
     51     //
     52     // This class exists to avoid having a circular reference between the
     53     // BufferQueue object and the consumer object.  The reason this can't be a weak
     54     // reference in the BufferQueue class is because we're planning to expose the
     55     // consumer side of a BufferQueue as a binder interface, which doesn't support
     56     // weak references.
     57     class ProxyConsumerListener : public BnConsumerListener {
     58     public:
     59         explicit ProxyConsumerListener(const wp<ConsumerListener>& consumerListener);
     60         virtual ~ProxyConsumerListener();
     61         void onDisconnect() override;
     62         void onFrameAvailable(const BufferItem& item) override;
     63         void onFrameReplaced(const BufferItem& item) override;
     64         void onBuffersReleased() override;
     65         void onSidebandStreamChanged() override;
     66         void addAndGetFrameTimestamps(
     67                 const NewFrameEventsEntry* newTimestamps,
     68                 FrameEventHistoryDelta* outDelta) override;
     69     private:
     70         // mConsumerListener is a weak reference to the IConsumerListener.  This is
     71         // the raison d'etre of ProxyConsumerListener.
     72         wp<ConsumerListener> mConsumerListener;
     73     };
     74 
     75     // BufferQueue manages a pool of gralloc memory slots to be used by
     76     // producers and consumers. allocator is used to allocate all the
     77     // needed gralloc buffers.
     78     static void createBufferQueue(sp<IGraphicBufferProducer>* outProducer,
     79             sp<IGraphicBufferConsumer>* outConsumer,
     80             bool consumerIsSurfaceFlinger = false);
     81 
     82     BufferQueue() = delete; // Create through createBufferQueue
     83 };
     84 
     85 // ----------------------------------------------------------------------------
     86 }; // namespace android
     87 
     88 #endif // ANDROID_GUI_BUFFERQUEUE_H
     89