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_CAPTURER_HELPER_H_ 12 #define MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_ 13 14 #include <memory> 15 16 #include "modules/desktop_capture/desktop_geometry.h" 17 #include "modules/desktop_capture/desktop_region.h" 18 #include "rtc_base/synchronization/mutex.h" 19 #include "rtc_base/thread_annotations.h" 20 21 namespace webrtc { 22 23 // ScreenCapturerHelper is intended to be used by an implementation of the 24 // ScreenCapturer interface. It maintains a thread-safe invalid region, and 25 // the size of the most recently captured screen, on behalf of the 26 // ScreenCapturer that owns it. 27 class ScreenCapturerHelper { 28 public: 29 ScreenCapturerHelper() = default; 30 ~ScreenCapturerHelper() = default; 31 32 ScreenCapturerHelper(const ScreenCapturerHelper&) = delete; 33 ScreenCapturerHelper& operator=(const ScreenCapturerHelper&) = delete; 34 35 // Clear out the invalid region. 36 void ClearInvalidRegion(); 37 38 // Invalidate the specified region. 39 void InvalidateRegion(const DesktopRegion& invalid_region); 40 41 // Invalidate the entire screen, of a given size. 42 void InvalidateScreen(const DesktopSize& size); 43 44 // Copies current invalid region to `invalid_region` clears invalid region 45 // storage for the next frame. 46 void TakeInvalidRegion(DesktopRegion* invalid_region); 47 48 // Access the size of the most recently captured screen. 49 const DesktopSize& size_most_recent() const; 50 void set_size_most_recent(const DesktopSize& size); 51 52 // Lossy compression can result in color values leaking between pixels in one 53 // block. If part of a block changes, then unchanged parts of that block can 54 // be changed in the compressed output. So we need to re-render an entire 55 // block whenever part of the block changes. 56 // 57 // If `log_grid_size` is >= 1, then this function makes TakeInvalidRegion() 58 // produce an invalid region expanded so that its vertices lie on a grid of 59 // size 2 ^ `log_grid_size`. The expanded region is then clipped to the size 60 // of the most recently captured screen, as previously set by 61 // set_size_most_recent(). 62 // If `log_grid_size` is <= 0, then the invalid region is not expanded. 63 void SetLogGridSize(int log_grid_size); 64 65 // Expands a region so that its vertices all lie on a grid. 66 // The grid size must be >= 2, so `log_grid_size` must be >= 1. 67 static void ExpandToGrid(const DesktopRegion& region, 68 int log_grid_size, 69 DesktopRegion* result); 70 71 private: 72 // A region that has been manually invalidated (through InvalidateRegion). 73 // These will be returned as dirty_region in the capture data during the next 74 // capture. 75 DesktopRegion invalid_region_ RTC_GUARDED_BY(invalid_region_mutex_); 76 77 // A lock protecting `invalid_region_` across threads. 78 Mutex invalid_region_mutex_; 79 80 // The size of the most recently captured screen. 81 DesktopSize size_most_recent_; 82 83 // The log (base 2) of the size of the grid to which the invalid region is 84 // expanded. 85 // If the value is <= 0, then the invalid region is not expanded to a grid. 86 int log_grid_size_ = 0; 87 }; 88 89 } // namespace webrtc 90 91 #endif // MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_ 92