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1 /* | |
2 * Copyright (c) 2016 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 #include "webrtc/modules/desktop_capture/screen_capturer_differ_wrapper.h" | |
12 | |
13 #include <string.h> | |
14 | |
15 #include <algorithm> | |
16 #include <utility> | |
17 | |
18 #include "webrtc/base/checks.h" | |
19 #include "webrtc/base/timeutils.h" | |
20 #include "webrtc/modules/desktop_capture/desktop_geometry.h" | |
21 #include "webrtc/modules/desktop_capture/differ_block.h" | |
22 | |
23 namespace webrtc { | |
24 | |
25 namespace { | |
26 | |
27 // Returns true if (0, 0) - (|width|, |height|) vector in |old_buffer| and | |
28 // |new_buffer| are equal. |width| should be less than 32 | |
29 // (defined by kBlockSize), otherwise BlockDifference() should be used. | |
30 bool PartialBlockDifference(const uint8_t* old_buffer, | |
31 const uint8_t* new_buffer, | |
32 int width, | |
33 int height, | |
34 int stride) { | |
35 RTC_DCHECK_LT(width, kBlockSize); | |
36 const int width_bytes = width * DesktopFrame::kBytesPerPixel; | |
37 for (int i = 0; i < height; i++) { | |
38 if (memcmp(old_buffer, new_buffer, width_bytes) != 0) { | |
39 return true; | |
40 } | |
41 old_buffer += stride; | |
42 new_buffer += stride; | |
43 } | |
44 return false; | |
45 } | |
46 | |
47 // Compares columns in the range of [|left|, |right|), in a row in the | |
48 // range of [|top|, |top| + |height|), starts from |old_buffer| and | |
49 // |new_buffer|, and outputs updated regions into |output|. |stride| is the | |
50 // DesktopFrame::stride(). | |
51 void CompareRow(const uint8_t* old_buffer, | |
52 const uint8_t* new_buffer, | |
53 const int left, | |
54 const int right, | |
55 const int top, | |
56 const int bottom, | |
57 const int stride, | |
58 DesktopRegion* const output) { | |
59 const int block_x_offset = kBlockSize * DesktopFrame::kBytesPerPixel; | |
60 const int width = right - left; | |
61 const int height = bottom - top; | |
62 const int block_count = (width - 1) / kBlockSize; | |
63 const int last_block_width = width - block_count * kBlockSize; | |
64 RTC_DCHECK(last_block_width <= kBlockSize && last_block_width > 0); | |
65 | |
66 // The first block-column in a continuous dirty area in current block-row. | |
67 int first_dirty_x_block = -1; | |
68 | |
69 // We always need to add dirty area into |output| in the last block, so handle | |
70 // it separatedly. | |
71 for (int x = 0; x < block_count; x++) { | |
72 if (BlockDifference(old_buffer, new_buffer, height, stride)) { | |
73 if (first_dirty_x_block == -1) { | |
74 // This is the first dirty block in a continuous dirty area. | |
75 first_dirty_x_block = x; | |
76 } | |
77 } else if (first_dirty_x_block != -1) { | |
78 // The block on the left is the last dirty block in a continuous | |
79 // dirty area. | |
80 output->AddRect(DesktopRect::MakeLTRB( | |
81 first_dirty_x_block * kBlockSize + left, top, | |
82 x * kBlockSize + left, bottom)); | |
83 first_dirty_x_block = -1; | |
84 } | |
85 old_buffer += block_x_offset; | |
86 new_buffer += block_x_offset; | |
87 } | |
88 | |
89 bool last_block_diff; | |
90 if (last_block_width < kBlockSize) { | |
91 // The last one is a partial vector. | |
92 last_block_diff = PartialBlockDifference( | |
93 old_buffer, new_buffer, last_block_width, height, stride); | |
94 } else { | |
95 last_block_diff = | |
96 BlockDifference(old_buffer, new_buffer, height, stride); | |
97 } | |
98 if (last_block_diff) { | |
99 if (first_dirty_x_block == -1) { | |
100 first_dirty_x_block = block_count; | |
101 } | |
102 output->AddRect( | |
103 DesktopRect::MakeLTRB(first_dirty_x_block * kBlockSize + left, | |
104 top, right, bottom)); | |
105 } else if (first_dirty_x_block != -1) { | |
106 output->AddRect(DesktopRect::MakeLTRB( | |
107 first_dirty_x_block * kBlockSize + left, top, | |
108 block_count * kBlockSize + left, bottom)); | |
109 } | |
110 } | |
111 | |
112 // Compares |rect| area in |old_frame| and |new_frame|, and outputs dirty | |
113 // regions into |output|. | |
114 void CompareFrames(const DesktopFrame& old_frame, | |
115 const DesktopFrame& new_frame, | |
116 DesktopRect rect, | |
117 DesktopRegion* const output) { | |
118 RTC_DCHECK(old_frame.size().equals(new_frame.size())); | |
119 RTC_DCHECK_EQ(old_frame.stride(), new_frame.stride()); | |
120 rect.IntersectWith(DesktopRect::MakeSize(old_frame.size())); | |
121 | |
122 const int y_block_count = (rect.height() - 1) / kBlockSize; | |
123 const int last_y_block_height = rect.height() - y_block_count * kBlockSize; | |
124 // Offset from the start of one block-row to the next. | |
125 const int block_y_stride = old_frame.stride() * kBlockSize; | |
126 const uint8_t* prev_block_row_start = | |
127 old_frame.GetFrameDataAtPos(rect.top_left()); | |
128 const uint8_t* curr_block_row_start = | |
129 new_frame.GetFrameDataAtPos(rect.top_left()); | |
130 | |
131 int top = rect.top(); | |
132 // The last row may have a different height, so we handle it separately. | |
133 for (int y = 0; y < y_block_count; y++) { | |
134 CompareRow(prev_block_row_start, curr_block_row_start, rect.left(), | |
135 rect.right(), top, top + kBlockSize, | |
136 old_frame.stride(), output); | |
137 top += kBlockSize; | |
138 prev_block_row_start += block_y_stride; | |
139 curr_block_row_start += block_y_stride; | |
140 } | |
141 CompareRow(prev_block_row_start, curr_block_row_start, rect.left(), | |
142 rect.right(), top, top + last_y_block_height, | |
143 old_frame.stride(), output); | |
144 } | |
145 | |
146 } // namespace | |
147 | |
148 ScreenCapturerDifferWrapper::ScreenCapturerDifferWrapper( | |
149 std::unique_ptr<ScreenCapturer> base_capturer) | |
150 : base_capturer_(std::move(base_capturer)) { | |
151 RTC_DCHECK(base_capturer_); | |
152 } | |
153 | |
154 ScreenCapturerDifferWrapper::~ScreenCapturerDifferWrapper() {} | |
155 | |
156 void ScreenCapturerDifferWrapper::Start(DesktopCapturer::Callback* callback) { | |
157 callback_ = callback; | |
158 base_capturer_->Start(this); | |
159 } | |
160 | |
161 void ScreenCapturerDifferWrapper::SetSharedMemoryFactory( | |
162 std::unique_ptr<SharedMemoryFactory> shared_memory_factory) { | |
163 base_capturer_->SetSharedMemoryFactory(std::move(shared_memory_factory)); | |
164 } | |
165 | |
166 void ScreenCapturerDifferWrapper::CaptureFrame() { | |
167 base_capturer_->CaptureFrame(); | |
168 } | |
169 | |
170 bool ScreenCapturerDifferWrapper::GetScreenList(ScreenList* screens) { | |
171 return base_capturer_->GetScreenList(screens); | |
172 } | |
173 | |
174 bool ScreenCapturerDifferWrapper::SelectScreen(ScreenId id) { | |
175 return base_capturer_->SelectScreen(id); | |
176 } | |
177 | |
178 void ScreenCapturerDifferWrapper::OnCaptureResult( | |
179 Result result, | |
180 std::unique_ptr<DesktopFrame> input_frame) { | |
181 int64_t start_time_nanos = rtc::TimeNanos(); | |
182 if (!input_frame) { | |
183 callback_->OnCaptureResult(result, nullptr); | |
184 return; | |
185 } | |
186 RTC_DCHECK(result == Result::SUCCESS); | |
187 | |
188 std::unique_ptr<SharedDesktopFrame> frame = | |
189 SharedDesktopFrame::Wrap(std::move(input_frame)); | |
190 if (last_frame_ && | |
191 (last_frame_->size().width() != frame->size().width() || | |
192 last_frame_->size().height() != frame->size().height() || | |
193 last_frame_->stride() != frame->stride())) { | |
194 last_frame_.reset(); | |
195 } | |
196 | |
197 if (last_frame_) { | |
198 DesktopRegion hints; | |
199 hints.Swap(frame->GetUnderlyingFrame()->mutable_updated_region()); | |
200 for (DesktopRegion::Iterator it(hints); !it.IsAtEnd(); it.Advance()) { | |
201 CompareFrames(*last_frame_, *frame, it.rect(), | |
202 frame->mutable_updated_region()); | |
203 } | |
204 } else { | |
205 frame->mutable_updated_region()->SetRect( | |
206 DesktopRect::MakeSize(frame->size())); | |
207 } | |
208 last_frame_ = frame->Share(); | |
209 | |
210 frame->set_capture_time_ms(frame->GetUnderlyingFrame()->capture_time_ms() + | |
211 (rtc::TimeNanos() - start_time_nanos) / | |
212 rtc::kNumNanosecsPerMillisec); | |
213 callback_->OnCaptureResult(result, std::move(frame)); | |
214 } | |
215 | |
216 } // namespace webrtc | |
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