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      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 #include "HWComposerBufferCache.h"
     18 
     19 #include <gui/BufferQueue.h>
     20 
     21 namespace android {
     22 
     23 HWComposerBufferCache::HWComposerBufferCache()
     24 {
     25     mBuffers.reserve(BufferQueue::NUM_BUFFER_SLOTS);
     26 }
     27 
     28 void HWComposerBufferCache::getHwcBuffer(int slot,
     29         const sp<GraphicBuffer>& buffer,
     30         uint32_t* outSlot, sp<GraphicBuffer>* outBuffer)
     31 {
     32     if (slot == BufferQueue::INVALID_BUFFER_SLOT || slot < 0) {
     33         // default to slot 0
     34         slot = 0;
     35     }
     36 
     37     if (static_cast<size_t>(slot) >= mBuffers.size()) {
     38         mBuffers.resize(slot + 1);
     39     }
     40 
     41     *outSlot = slot;
     42 
     43     if (mBuffers[slot] == buffer) {
     44         // already cached in HWC, skip sending the buffer
     45         *outBuffer = nullptr;
     46     } else {
     47         *outBuffer = buffer;
     48 
     49         // update cache
     50         mBuffers[slot] = buffer;
     51     }
     52 }
     53 
     54 } // namespace android
     55