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1 /*
2  *  Copyright (c) 2017 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_BLANK_DETECTOR_DESKTOP_CAPTURER_WRAPPER_H_
12 #define MODULES_DESKTOP_CAPTURE_BLANK_DETECTOR_DESKTOP_CAPTURER_WRAPPER_H_
13 
14 #include <memory>
15 
16 #include "modules/desktop_capture/desktop_capture_types.h"
17 #include "modules/desktop_capture/desktop_capturer.h"
18 #include "modules/desktop_capture/desktop_frame.h"
19 #include "modules/desktop_capture/rgba_color.h"
20 #include "modules/desktop_capture/shared_memory.h"
21 
22 namespace webrtc {
23 
24 // A DesktopCapturer wrapper detects the return value of its owned
25 // DesktopCapturer implementation. If sampled pixels returned by the
26 // DesktopCapturer implementation all equal to the blank pixel, this wrapper
27 // returns ERROR_TEMPORARY. If the DesktopCapturer implementation fails for too
28 // many times, this wrapper returns ERROR_PERMANENT.
29 class BlankDetectorDesktopCapturerWrapper final
30     : public DesktopCapturer,
31       public DesktopCapturer::Callback {
32  public:
33   // Creates BlankDetectorDesktopCapturerWrapper. BlankDesktopCapturerWrapper
34   // takes ownership of |capturer|. The |blank_pixel| is the unmodified color
35   // returned by the |capturer|.
36   BlankDetectorDesktopCapturerWrapper(std::unique_ptr<DesktopCapturer> capturer,
37                                       RgbaColor blank_pixel);
38   ~BlankDetectorDesktopCapturerWrapper() override;
39 
40   // DesktopCapturer interface.
41   void Start(DesktopCapturer::Callback* callback) override;
42   void SetSharedMemoryFactory(
43       std::unique_ptr<SharedMemoryFactory> shared_memory_factory) override;
44   void CaptureFrame() override;
45   void SetExcludedWindow(WindowId window) override;
46   bool GetSourceList(SourceList* sources) override;
47   bool SelectSource(SourceId id) override;
48   bool FocusOnSelectedSource() override;
49   bool IsOccluded(const DesktopVector& pos) override;
50 
51  private:
52   // DesktopCapturer::Callback interface.
53   void OnCaptureResult(Result result,
54                        std::unique_ptr<DesktopFrame> frame) override;
55 
56   bool IsBlankFrame(const DesktopFrame& frame) const;
57 
58   // Detects whether pixel at (x, y) equals to |blank_pixel_|.
59   bool IsBlankPixel(const DesktopFrame& frame, int x, int y) const;
60 
61   const std::unique_ptr<DesktopCapturer> capturer_;
62   const RgbaColor blank_pixel_;
63 
64   // Whether a non-blank frame has been received.
65   bool non_blank_frame_received_ = false;
66 
67   // Whether the last frame is blank.
68   bool last_frame_is_blank_ = false;
69 
70   // Whether current frame is the first frame.
71   bool is_first_frame_ = true;
72 
73   DesktopCapturer::Callback* callback_ = nullptr;
74 };
75 
76 }  // namespace webrtc
77 
78 #endif  // MODULES_DESKTOP_CAPTURE_BLANK_DETECTOR_DESKTOP_CAPTURER_WRAPPER_H_
79