zijiehe fef8653c5a An early analysis shows in DirectX based capturer, Windows API returns larger
dirty region than the real screen change. A similar behavior may happen on other
platforms with damage notification support. So it's better to have an individual
layer to handle the Differ logic, and remove capturing independent logic out of
each ScreenCapturer* implementation.

So this change does following things,
1. Update differ_block to handle variable height. differ_block_sse2 has been
renamed to differ_vector_sse2.

2. A new ScreenCapturerDifferWrapper implementation to help set
DesktopFrame::updated_region(). It uses an underlying ScreenCapturer to do
the real capture work, and updates the updated region of DesktopFrame returned
from OnCaptureResult function.

3. FakeDesktopCapturer and FakeScreenCapturer to generate controllable
DesktopFrame by using DesktopFrameGenerator and DesktopFramePainter.

4. Test ScreenCapturerDifferWrapper by using FakeScreenCapturer.

After this change, we can eventually remove all Differ logic from
ScreenCapturer* implementations, and fix a potential crash bug in
ScreenCapturerLinux class. It wrongly assumes previous_frame() has a same size
as current_frame(). https://goo.gl/3nSqOC

BUG=633802

TBR=kjellander@webrtc.org

Review-Url: https://codereview.webrtc.org/2202443002
Cr-Commit-Position: refs/heads/master@{#14076}
2016-09-05 22:26:40 +00:00

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/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_DIFFER_BLOCK_H_
#define WEBRTC_MODULES_DESKTOP_CAPTURE_DIFFER_BLOCK_H_
#include <stdint.h>
namespace webrtc {
// Size (in pixels) of each square block used for diffing. This must be a
// multiple of sizeof(uint64)/8.
const int kBlockSize = 32;
// Format: BGRA 32 bit.
const int kBytesPerPixel = 4;
// Low level function to compare 2 vectors of pixels of size kBlockSize. Returns
// whether the blocks differ.
bool VectorDifference(const uint8_t* image1, const uint8_t* image2);
// Low level function to compare 2 blocks of pixels of size
// (kBlockSize, |height|). Returns whether the blocks differ.
bool BlockDifference(const uint8_t* image1,
const uint8_t* image2,
int height,
int stride);
// Low level function to compare 2 blocks of pixels of size
// (kBlockSize, kBlockSize). Returns whether the blocks differ.
bool BlockDifference(const uint8_t* image1,
const uint8_t* image2,
int stride);
} // namespace webrtc
#endif // WEBRTC_MODULES_DESKTOP_CAPTURE_DIFFER_BLOCK_H_