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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef MEDIA_VIDEO_CAPTURE_SCREEN_DIFFER_H_ | |
| 6 #define MEDIA_VIDEO_CAPTURE_SCREEN_DIFFER_H_ | |
| 7 | |
| 8 #include <vector> | |
| 9 | |
| 10 #include "base/basictypes.h" | |
| 11 #include "base/memory/scoped_ptr.h" | |
| 12 #include "media/base/media_export.h" | |
| 13 #include "third_party/webrtc/modules/desktop_capture/desktop_region.h" | |
| 14 | |
| 15 namespace media { | |
| 16 | |
| 17 typedef uint8 DiffInfo; | |
| 18 | |
| 19 // TODO: Simplify differ now that we are working with webrtc::DesktopRegion. | |
| 20 // diff_info_ should no longer be needed, as we can put our data directly into | |
| 21 // the region that we are calculating. | |
| 22 // http://crbug.com/92379 | |
| 23 // TODO(sergeyu): Rename this class to something more sensible, e.g. | |
| 24 // ScreenCaptureFrameDifferencer. | |
| 25 class MEDIA_EXPORT Differ { | |
| 26 public: | |
| 27 // Create a differ that operates on bitmaps with the specified width, height | |
| 28 // and bytes_per_pixel. | |
| 29 Differ(int width, int height, int bytes_per_pixel, int stride); | |
| 30 ~Differ(); | |
| 31 | |
| 32 int width() { return width_; } | |
| 33 int height() { return height_; } | |
| 34 int bytes_per_pixel() { return bytes_per_pixel_; } | |
| 35 int bytes_per_row() { return bytes_per_row_; } | |
| 36 | |
| 37 // Given the previous and current screen buffer, calculate the dirty region | |
| 38 // that encloses all of the changed pixels in the new screen. | |
| 39 void CalcDirtyRegion(const void* prev_buffer, const void* curr_buffer, | |
| 40 webrtc::DesktopRegion* region); | |
| 41 | |
| 42 private: | |
| 43 // Allow tests to access our private parts. | |
| 44 friend class DifferTest; | |
| 45 | |
| 46 // Identify all of the blocks that contain changed pixels. | |
| 47 void MarkDirtyBlocks(const void* prev_buffer, const void* curr_buffer); | |
| 48 | |
| 49 // After the dirty blocks have been identified, this routine merges adjacent | |
| 50 // blocks into a region. | |
| 51 // The goal is to minimize the region that covers the dirty blocks. | |
| 52 void MergeBlocks(webrtc::DesktopRegion* region); | |
| 53 | |
| 54 // Check for diffs in upper-left portion of the block. The size of the portion | |
| 55 // to check is specified by the |width| and |height| values. | |
| 56 // Note that if we force the capturer to always return images whose width and | |
| 57 // height are multiples of kBlockSize, then this will never be called. | |
| 58 DiffInfo DiffPartialBlock(const uint8* prev_buffer, const uint8* curr_buffer, | |
| 59 int stride, int width, int height); | |
| 60 | |
| 61 // Dimensions of screen. | |
| 62 int width_; | |
| 63 int height_; | |
| 64 | |
| 65 // Number of bytes for each pixel in source and dest bitmap. | |
| 66 // (Yes, they must match.) | |
| 67 int bytes_per_pixel_; | |
| 68 | |
| 69 // Number of bytes in each row of the image (AKA: stride). | |
| 70 int bytes_per_row_; | |
| 71 | |
| 72 // Diff information for each block in the image. | |
| 73 scoped_ptr<DiffInfo[]> diff_info_; | |
| 74 | |
| 75 // Dimensions and total size of diff info array. | |
| 76 int diff_info_width_; | |
| 77 int diff_info_height_; | |
| 78 int diff_info_size_; | |
| 79 | |
| 80 DISALLOW_COPY_AND_ASSIGN(Differ); | |
| 81 }; | |
| 82 | |
| 83 } // namespace media | |
| 84 | |
| 85 #endif // MEDIA_VIDEO_CAPTURE_SCREEN_DIFFER_H_ | |
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