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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 MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_
#define MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_
#include <memory>
#include "modules/desktop_capture/desktop_geometry.h"
#include "modules/desktop_capture/desktop_region.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
// ScreenCapturerHelper is intended to be used by an implementation of the
// ScreenCapturer interface. It maintains a thread-safe invalid region, and
// the size of the most recently captured screen, on behalf of the
// ScreenCapturer that owns it.
class ScreenCapturerHelper {
public:
ScreenCapturerHelper() = default;
~ScreenCapturerHelper() = default;
ScreenCapturerHelper(const ScreenCapturerHelper&) = delete;
ScreenCapturerHelper& operator=(const ScreenCapturerHelper&) = delete;
// Clear out the invalid region.
void ClearInvalidRegion();
// Invalidate the specified region.
void InvalidateRegion(const DesktopRegion& invalid_region);
// Invalidate the entire screen, of a given size.
void InvalidateScreen(const DesktopSize& size);
// Copies current invalid region to `invalid_region` clears invalid region
// storage for the next frame.
void TakeInvalidRegion(DesktopRegion* invalid_region);
// Access the size of the most recently captured screen.
const DesktopSize& size_most_recent() const;
void set_size_most_recent(const DesktopSize& size);
// Lossy compression can result in color values leaking between pixels in one
// block. If part of a block changes, then unchanged parts of that block can
// be changed in the compressed output. So we need to re-render an entire
// block whenever part of the block changes.
//
// If `log_grid_size` is >= 1, then this function makes TakeInvalidRegion()
// produce an invalid region expanded so that its vertices lie on a grid of
// size 2 ^ `log_grid_size`. The expanded region is then clipped to the size
// of the most recently captured screen, as previously set by
// set_size_most_recent().
// If `log_grid_size` is <= 0, then the invalid region is not expanded.
void SetLogGridSize(int log_grid_size);
// Expands a region so that its vertices all lie on a grid.
// The grid size must be >= 2, so `log_grid_size` must be >= 1.
static void ExpandToGrid(const DesktopRegion& region,
int log_grid_size,
DesktopRegion* result);
private:
// A region that has been manually invalidated (through InvalidateRegion).
// These will be returned as dirty_region in the capture data during the next
// capture.
DesktopRegion invalid_region_ RTC_GUARDED_BY(invalid_region_mutex_);
// A lock protecting `invalid_region_` across threads.
Mutex invalid_region_mutex_;
// The size of the most recently captured screen.
DesktopSize size_most_recent_;
// The log (base 2) of the size of the grid to which the invalid region is
// expanded.
// If the value is <= 0, then the invalid region is not expanded to a grid.
int log_grid_size_ = 0;
};
} // namespace webrtc
#endif // MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_
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