sergeyu@chromium.org | 6c82a7e | 2013-06-04 18:51:23 +0000 | [diff] [blame] | 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_ |