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
26namespace android {
27// ---------------------------------------------------------------------------
28
29class 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.
40class HWComposerBufferCache {
41public:
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
52private:
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