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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <cstdint>
#include <vector>
// TODO(b/129481165): remove the #pragma below and fix conversion issues
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wconversion"
#include <gui/BufferQueue.h>
// TODO(b/129481165): remove the #pragma below and fix conversion issues
#pragma clang diagnostic pop // ignored "-Wconversion"
#include <utils/StrongPointer.h>
namespace android {
class GraphicBuffer;
namespace compositionengine::impl {
// With HIDLized hwcomposer HAL, the HAL can maintain a buffer cache for each
// HWC display and layer. When updating a display target or a layer buffer,
// we have the option to send the buffer handle over or to request the HAL to
// retrieve it from its cache. The latter is cheaper since it eliminates the
// overhead to transfer the handle over the trasport layer, and the overhead
// for the HAL to clone and retain the handle.
//
// To be able to find out whether a buffer is already in the HAL's cache, we
// use HWComposerBufferCache to mirror the cache in SF.
class HwcBufferCache {
public:
HwcBufferCache();
// Given a buffer, return the HWC cache slot and
// buffer to be sent to HWC.
//
// outBuffer is set to buffer when buffer is not in the HWC cache;
// otherwise, outBuffer is set to nullptr.
void getHwcBuffer(int slot, const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
sp<GraphicBuffer>* outBuffer);
private:
// an array where the index corresponds to a slot and the value corresponds to a (counter,
// buffer) pair. "counter" is a unique value that indicates the last time this slot was updated
// or used and allows us to keep track of the least-recently used buffer.
wp<GraphicBuffer> mBuffers[BufferQueue::NUM_BUFFER_SLOTS];
};
} // namespace compositionengine::impl
} // namespace android
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