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 WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_ 12 #define WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_ 13 14 #include "webrtc/modules/desktop_capture/shared_desktop_frame.h" 15 #include "webrtc/system_wrappers/interface/scoped_ptr.h" 16 #include "webrtc/typedefs.h" 17 18 namespace webrtc { 19 class DesktopFrame; 20 } // namespace webrtc 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 class ScreenCaptureFrameQueue { 38 public: 39 ScreenCaptureFrameQueue(); 40 ~ScreenCaptureFrameQueue(); 41 42 // Moves to the next frame in the queue, moving the 'current' frame to become 43 // the 'previous' one. 44 void MoveToNextFrame(); 45 46 // Replaces the current frame with a new one allocated by the caller. The 47 // existing frame (if any) is destroyed. Takes ownership of |frame|. 48 void ReplaceCurrentFrame(DesktopFrame* frame); 49 50 // Marks all frames obsolete and resets the previous frame pointer. No 51 // frames are freed though as the caller can still access them. 52 void Reset(); 53 54 SharedDesktopFrame* current_frame() const { 55 return frames_[current_].get(); 56 } 57 58 SharedDesktopFrame* previous_frame() const { 59 return frames_[(current_ + kQueueLength - 1) % kQueueLength].get(); 60 } 61 62 private: 63 // Index of the current frame. 64 int current_; 65 66 static const int kQueueLength = 2; 67 scoped_ptr<SharedDesktopFrame> frames_[kQueueLength]; 68 69 DISALLOW_COPY_AND_ASSIGN(ScreenCaptureFrameQueue); 70 }; 71 72 } // namespace webrtc 73 74 #endif // WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_ 75
