1 /* 2 * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_ 12 #define MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_ 13 14 #include <memory> 15 16 #include "rtc_base/constructor_magic.h" 17 // TODO(zijiehe): These headers are not used in this file, but to avoid build 18 // break in remoting/host. We should add headers in each individual files. 19 #include "modules/desktop_capture/desktop_frame.h" // Remove 20 #include "modules/desktop_capture/shared_desktop_frame.h" // Remove 21 22 namespace webrtc { 23 24 // Represents a queue of reusable video frames. Provides access to the 'current' 25 // frame - the frame that the caller is working with at the moment, and to the 26 // 'previous' frame - the predecessor of the current frame swapped by 27 // MoveToNextFrame() call, if any. 28 // 29 // The caller is expected to (re)allocate frames if current_frame() returns 30 // NULL. The caller can mark all frames in the queue for reallocation (when, 31 // say, frame dimensions change). The queue records which frames need updating 32 // which the caller can query. 33 // 34 // Frame consumer is expected to never hold more than kQueueLength frames 35 // created by this function and it should release the earliest one before trying 36 // to capture a new frame (i.e. before MoveToNextFrame() is called). 37 template <typename FrameType> 38 class ScreenCaptureFrameQueue { 39 public: ScreenCaptureFrameQueue()40 ScreenCaptureFrameQueue() : current_(0) {} 41 ~ScreenCaptureFrameQueue() = default; 42 43 // Moves to the next frame in the queue, moving the 'current' frame to become 44 // the 'previous' one. MoveToNextFrame()45 void MoveToNextFrame() { current_ = (current_ + 1) % kQueueLength; } 46 47 // Replaces the current frame with a new one allocated by the caller. The 48 // existing frame (if any) is destroyed. Takes ownership of |frame|. ReplaceCurrentFrame(std::unique_ptr<FrameType> frame)49 void ReplaceCurrentFrame(std::unique_ptr<FrameType> frame) { 50 frames_[current_] = std::move(frame); 51 } 52 53 // Marks all frames obsolete and resets the previous frame pointer. No 54 // frames are freed though as the caller can still access them. Reset()55 void Reset() { 56 for (int i = 0; i < kQueueLength; i++) { 57 frames_[i].reset(); 58 } 59 current_ = 0; 60 } 61 current_frame()62 FrameType* current_frame() const { return frames_[current_].get(); } 63 previous_frame()64 FrameType* previous_frame() const { 65 return frames_[(current_ + kQueueLength - 1) % kQueueLength].get(); 66 } 67 68 private: 69 // Index of the current frame. 70 int current_; 71 72 static const int kQueueLength = 2; 73 std::unique_ptr<FrameType> frames_[kQueueLength]; 74 75 RTC_DISALLOW_COPY_AND_ASSIGN(ScreenCaptureFrameQueue); 76 }; 77 78 } // namespace webrtc 79 80 #endif // MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_ 81