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/constructor_magic.h" 19 #include "rtc_base/synchronization/rw_lock_wrapper.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(); 30 ~ScreenCapturerHelper(); 31 32 // Clear out the invalid region. 33 void ClearInvalidRegion(); 34 35 // Invalidate the specified region. 36 void InvalidateRegion(const DesktopRegion& invalid_region); 37 38 // Invalidate the entire screen, of a given size. 39 void InvalidateScreen(const DesktopSize& size); 40 41 // Copies current invalid region to |invalid_region| clears invalid region 42 // storage for the next frame. 43 void TakeInvalidRegion(DesktopRegion* invalid_region); 44 45 // Access the size of the most recently captured screen. 46 const DesktopSize& size_most_recent() const; 47 void set_size_most_recent(const DesktopSize& size); 48 49 // Lossy compression can result in color values leaking between pixels in one 50 // block. If part of a block changes, then unchanged parts of that block can 51 // be changed in the compressed output. So we need to re-render an entire 52 // block whenever part of the block changes. 53 // 54 // If |log_grid_size| is >= 1, then this function makes TakeInvalidRegion() 55 // produce an invalid region expanded so that its vertices lie on a grid of 56 // size 2 ^ |log_grid_size|. The expanded region is then clipped to the size 57 // of the most recently captured screen, as previously set by 58 // set_size_most_recent(). 59 // If |log_grid_size| is <= 0, then the invalid region is not expanded. 60 void SetLogGridSize(int log_grid_size); 61 62 // Expands a region so that its vertices all lie on a grid. 63 // The grid size must be >= 2, so |log_grid_size| must be >= 1. 64 static void ExpandToGrid(const DesktopRegion& region, 65 int log_grid_size, 66 DesktopRegion* result); 67 68 private: 69 // A region that has been manually invalidated (through InvalidateRegion). 70 // These will be returned as dirty_region in the capture data during the next 71 // capture. 72 DesktopRegion invalid_region_; 73 74 // A lock protecting |invalid_region_| across threads. 75 std::unique_ptr<RWLockWrapper> invalid_region_lock_; 76 77 // The size of the most recently captured screen. 78 DesktopSize size_most_recent_; 79 80 // The log (base 2) of the size of the grid to which the invalid region is 81 // expanded. 82 // If the value is <= 0, then the invalid region is not expanded to a grid. 83 int log_grid_size_; 84 85 RTC_DISALLOW_COPY_AND_ASSIGN(ScreenCapturerHelper); 86 }; 87 88 } // namespace webrtc 89 90 #endif // MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_ 91