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/*
* Copyright (c) 2016 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.
*/
#include "modules/desktop_capture/desktop_capturer_differ_wrapper.h"
#include <stdint.h>
#include <string.h>
#include <utility>
#include "modules/desktop_capture/desktop_geometry.h"
#include "modules/desktop_capture/desktop_region.h"
#include "modules/desktop_capture/differ_block.h"
#include "rtc_base/checks.h"
#include "rtc_base/time_utils.h"
namespace webrtc {
namespace {
// Returns true if (0, 0) - (`width`, `height`) vector in `old_buffer` and
// `new_buffer` are equal. `width` should be less than 32
// (defined by kBlockSize), otherwise BlockDifference() should be used.
bool PartialBlockDifference(const uint8_t* old_buffer,
const uint8_t* new_buffer,
int width,
int height,
int stride) {
RTC_DCHECK_LT(width, kBlockSize);
const int width_bytes = width * DesktopFrame::kBytesPerPixel;
for (int i = 0; i < height; i++) {
if (memcmp(old_buffer, new_buffer, width_bytes) != 0) {
return true;
}
old_buffer += stride;
new_buffer += stride;
}
return false;
}
// Compares columns in the range of [`left`, `right`), in a row in the
// range of [`top`, `top` + `height`), starts from `old_buffer` and
// `new_buffer`, and outputs updated regions into `output`. `stride` is the
// DesktopFrame::stride().
void CompareRow(const uint8_t* old_buffer,
const uint8_t* new_buffer,
const int left,
const int right,
const int top,
const int bottom,
const int stride,
DesktopRegion* const output) {
const int block_x_offset = kBlockSize * DesktopFrame::kBytesPerPixel;
const int width = right - left;
const int height = bottom - top;
const int block_count = (width - 1) / kBlockSize;
const int last_block_width = width - block_count * kBlockSize;
RTC_DCHECK_GT(last_block_width, 0);
RTC_DCHECK_LE(last_block_width, kBlockSize);
// The first block-column in a continuous dirty area in current block-row.
int first_dirty_x_block = -1;
// We always need to add dirty area into `output` in the last block, so handle
// it separatedly.
for (int x = 0; x < block_count; x++) {
if (BlockDifference(old_buffer, new_buffer, height, stride)) {
if (first_dirty_x_block == -1) {
// This is the first dirty block in a continuous dirty area.
first_dirty_x_block = x;
}
} else if (first_dirty_x_block != -1) {
// The block on the left is the last dirty block in a continuous
// dirty area.
output->AddRect(
DesktopRect::MakeLTRB(first_dirty_x_block * kBlockSize + left, top,
x * kBlockSize + left, bottom));
first_dirty_x_block = -1;
}
old_buffer += block_x_offset;
new_buffer += block_x_offset;
}
bool last_block_diff;
if (last_block_width < kBlockSize) {
// The last one is a partial vector.
last_block_diff = PartialBlockDifference(old_buffer, new_buffer,
last_block_width, height, stride);
} else {
last_block_diff = BlockDifference(old_buffer, new_buffer, height, stride);
}
if (last_block_diff) {
if (first_dirty_x_block == -1) {
first_dirty_x_block = block_count;
}
output->AddRect(DesktopRect::MakeLTRB(
first_dirty_x_block * kBlockSize + left, top, right, bottom));
} else if (first_dirty_x_block != -1) {
output->AddRect(
DesktopRect::MakeLTRB(first_dirty_x_block * kBlockSize + left, top,
block_count * kBlockSize + left, bottom));
}
}
// Compares `rect` area in `old_frame` and `new_frame`, and outputs dirty
// regions into `output`.
void CompareFrames(const DesktopFrame& old_frame,
const DesktopFrame& new_frame,
DesktopRect rect,
DesktopRegion* const output) {
RTC_DCHECK(old_frame.size().equals(new_frame.size()));
RTC_DCHECK_EQ(old_frame.stride(), new_frame.stride());
rect.IntersectWith(DesktopRect::MakeSize(old_frame.size()));
const int y_block_count = (rect.height() - 1) / kBlockSize;
const int last_y_block_height = rect.height() - y_block_count * kBlockSize;
// Offset from the start of one block-row to the next.
const int block_y_stride = old_frame.stride() * kBlockSize;
const uint8_t* prev_block_row_start =
old_frame.GetFrameDataAtPos(rect.top_left());
const uint8_t* curr_block_row_start =
new_frame.GetFrameDataAtPos(rect.top_left());
int top = rect.top();
// The last row may have a different height, so we handle it separately.
for (int y = 0; y < y_block_count; y++) {
CompareRow(prev_block_row_start, curr_block_row_start, rect.left(),
rect.right(), top, top + kBlockSize, old_frame.stride(), output);
top += kBlockSize;
prev_block_row_start += block_y_stride;
curr_block_row_start += block_y_stride;
}
CompareRow(prev_block_row_start, curr_block_row_start, rect.left(),
rect.right(), top, top + last_y_block_height, old_frame.stride(),
output);
}
} // namespace
DesktopCapturerDifferWrapper::DesktopCapturerDifferWrapper(
std::unique_ptr<DesktopCapturer> base_capturer)
: base_capturer_(std::move(base_capturer)) {
RTC_DCHECK(base_capturer_);
}
DesktopCapturerDifferWrapper::~DesktopCapturerDifferWrapper() {}
void DesktopCapturerDifferWrapper::Start(DesktopCapturer::Callback* callback) {
callback_ = callback;
base_capturer_->Start(this);
}
void DesktopCapturerDifferWrapper::SetSharedMemoryFactory(
std::unique_ptr<SharedMemoryFactory> shared_memory_factory) {
base_capturer_->SetSharedMemoryFactory(std::move(shared_memory_factory));
}
void DesktopCapturerDifferWrapper::CaptureFrame() {
base_capturer_->CaptureFrame();
}
void DesktopCapturerDifferWrapper::SetExcludedWindow(WindowId window) {
base_capturer_->SetExcludedWindow(window);
}
bool DesktopCapturerDifferWrapper::GetSourceList(SourceList* sources) {
return base_capturer_->GetSourceList(sources);
}
bool DesktopCapturerDifferWrapper::SelectSource(SourceId id) {
return base_capturer_->SelectSource(id);
}
bool DesktopCapturerDifferWrapper::FocusOnSelectedSource() {
return base_capturer_->FocusOnSelectedSource();
}
bool DesktopCapturerDifferWrapper::IsOccluded(const DesktopVector& pos) {
return base_capturer_->IsOccluded(pos);
}
#if defined(WEBRTC_USE_GIO)
DesktopCaptureMetadata DesktopCapturerDifferWrapper::GetMetadata() {
return base_capturer_->GetMetadata();
}
#endif // defined(WEBRTC_USE_GIO)
void DesktopCapturerDifferWrapper::OnCaptureResult(
Result result,
std::unique_ptr<DesktopFrame> input_frame) {
int64_t start_time_nanos = rtc::TimeNanos();
if (!input_frame) {
callback_->OnCaptureResult(result, nullptr);
return;
}
RTC_DCHECK(result == Result::SUCCESS);
std::unique_ptr<SharedDesktopFrame> frame =
SharedDesktopFrame::Wrap(std::move(input_frame));
if (last_frame_ && (last_frame_->size().width() != frame->size().width() ||
last_frame_->size().height() != frame->size().height() ||
last_frame_->stride() != frame->stride())) {
last_frame_.reset();
}
if (last_frame_) {
DesktopRegion hints;
hints.Swap(frame->mutable_updated_region());
for (DesktopRegion::Iterator it(hints); !it.IsAtEnd(); it.Advance()) {
CompareFrames(*last_frame_, *frame, it.rect(),
frame->mutable_updated_region());
}
} else {
frame->mutable_updated_region()->SetRect(
DesktopRect::MakeSize(frame->size()));
}
last_frame_ = frame->Share();
frame->set_capture_time_ms(frame->capture_time_ms() +
(rtc::TimeNanos() - start_time_nanos) /
rtc::kNumNanosecsPerMillisec);
callback_->OnCaptureResult(result, std::move(frame));
}
} // namespace webrtc
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