Line data    Source code

       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 <memory>
      15             : 
      16             : #include "webrtc/base/constructormagic.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 "webrtc/modules/desktop_capture/desktop_frame.h"  // Remove
      20             : #include "webrtc/modules/desktop_capture/shared_desktop_frame.h"  // Remove
      21             : 
      22             : 
      23             : namespace webrtc {
      24             : 
      25             : // Represents a queue of reusable video frames. Provides access to the 'current'
      26             : // frame - the frame that the caller is working with at the moment, and to the
      27             : // 'previous' frame - the predecessor of the current frame swapped by
      28             : // MoveToNextFrame() call, if any.
      29             : //
      30             : // The caller is expected to (re)allocate frames if current_frame() returns
      31             : // NULL. The caller can mark all frames in the queue for reallocation (when,
      32             : // say, frame dimensions change). The queue records which frames need updating
      33             : // which the caller can query.
      34             : //
      35             : // Frame consumer is expected to never hold more than kQueueLength frames
      36             : // created by this function and it should release the earliest one before trying
      37             : // to capture a new frame (i.e. before MoveToNextFrame() is called).
      38             : template <typename FrameType>
      39             : class ScreenCaptureFrameQueue {
      40             :  public:
      41           0 :   ScreenCaptureFrameQueue() : current_(0) {}
      42           0 :   ~ScreenCaptureFrameQueue() = default;
      43             : 
      44             :   // Moves to the next frame in the queue, moving the 'current' frame to become
      45             :   // the 'previous' one.
      46           0 :   void MoveToNextFrame() {
      47           0 :     current_ = (current_ + 1) % kQueueLength;
      48           0 :   }
      49             : 
      50             :   // Replaces the current frame with a new one allocated by the caller. The
      51             :   // existing frame (if any) is destroyed. Takes ownership of |frame|.
      52           0 :   void ReplaceCurrentFrame(std::unique_ptr<FrameType> frame) {
      53           0 :     frames_[current_] = std::move(frame);
      54           0 :   }
      55             : 
      56             :   // Marks all frames obsolete and resets the previous frame pointer. No
      57             :   // frames are freed though as the caller can still access them.
      58           0 :   void Reset() {
      59           0 :     for (int i = 0; i < kQueueLength; i++) {
      60           0 :       frames_[i].reset();
      61             :     }
      62           0 :     current_ = 0;
      63           0 :   }
      64             : 
      65           0 :   FrameType* current_frame() const {
      66           0 :     return frames_[current_].get();
      67             :   }
      68             : 
      69           0 :   FrameType* previous_frame() const {
      70           0 :     return frames_[(current_ + kQueueLength - 1) % kQueueLength].get();
      71             :   }
      72             : 
      73             :  private:
      74             :   // Index of the current frame.
      75             :   int current_;
      76             : 
      77             :   static const int kQueueLength = 2;
      78             :   std::unique_ptr<FrameType> frames_[kQueueLength];
      79             : 
      80             :   RTC_DISALLOW_COPY_AND_ASSIGN(ScreenCaptureFrameQueue);
      81             : };
      82             : 
      83             : }  // namespace webrtc
      84             : 
      85             : #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURE_FRAME_QUEUE_H_