1 /*
2  * Copyright (C) 2017 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_HWCOMPOSERBUFFERCACHE_H
18 #define ANDROID_SF_HWCOMPOSERBUFFERCACHE_H
19 
20 #include <stdint.h>
21 
22 #include <utils/StrongPointer.h>
23 
24 #include <vector>
25 
26 namespace android {
27 // ---------------------------------------------------------------------------
28 
29 class GraphicBuffer;
30 
31 // With HIDLized hwcomposer HAL, the HAL can maintain a buffer cache for each
32 // HWC display and layer.  When updating a display target or a layer buffer,
33 // we have the option to send the buffer handle over or to request the HAL to
34 // retrieve it from its cache.  The latter is cheaper since it eliminates the
35 // overhead to transfer the handle over the trasport layer, and the overhead
36 // for the HAL to clone and retain the handle.
37 //
38 // To be able to find out whether a buffer is already in the HAL's cache, we
39 // use HWComposerBufferCache to mirror the cache in SF.
40 class HWComposerBufferCache {
41 public:
42     HWComposerBufferCache();
43 
44     // Given a buffer queue slot and buffer, return the HWC cache slot and
45     // buffer to be sent to HWC.
46     //
47     // outBuffer is set to buffer when buffer is not in the HWC cache;
48     // otherwise, outBuffer is set to nullptr.
49     void getHwcBuffer(int slot, const sp<GraphicBuffer>& buffer,
50             uint32_t* outSlot, sp<GraphicBuffer>* outBuffer);
51 
52 private:
53     // a vector as we expect "slot" to be in the range of [0, 63] (that is,
54     // less than BufferQueue::NUM_BUFFER_SLOTS).
55     std::vector<sp<GraphicBuffer>> mBuffers;
56 };
57 
58 // ---------------------------------------------------------------------------
59 }; // namespace android
60 
61 #endif // ANDROID_SF_HWCOMPOSERBUFFERCACHE_H
62