[WebRTC] Add ScreenCapturerDifferWrapper to share Differ across ScreenCapturers

webrtc/modules/desktop_capture/desktop_frame_generator.cc

+/*
+ *  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 "webrtc/modules/desktop_capture/desktop_frame_generator.h"
+
+#include <stdint.h>
+#include <string.h>
+
+#include <memory>
+
+#include "webrtc/base/random.h"
+#include "webrtc/base/timeutils.h"
+
+namespace webrtc {
+
+namespace {
+
+// Sets |updated_region| to |frame|. If |enlarge_updated_region| is
+// true, this function will randomly enlarge each DesktopRect in
+// |updated_region|. But the enlarged DesktopRegion won't excceed the
+// frame->size(). If |add_random_updated_region| is true, several random
+// rectangles will also be included in |frame|.
+void SetUpdatedRegion(DesktopFrame* frame,
+                      const DesktopRegion& updated_region,
+                      bool enlarge_updated_region,
+                      int enlarge_range,
+                      bool add_random_updated_region) {
+  const DesktopRect screen_rect = DesktopRect::MakeSize(frame->size());
+  Random random(rtc::TimeMicros());
+  frame->mutable_updated_region()->Clear();
+  for (DesktopRegion::Iterator it(updated_region); !it.IsAtEnd();
+       it.Advance()) {
+    DesktopRect rect = it.rect();
+    if (enlarge_updated_region && enlarge_range > 0) {
+      rect.Extend(random.Rand(enlarge_range), random.Rand(enlarge_range),
+                  random.Rand(enlarge_range), random.Rand(enlarge_range));
+      rect.IntersectWith(screen_rect);
+    }
+    frame->mutable_updated_region()->AddRect(rect);
+  }
+
+  if (add_random_updated_region) {
+    for (int i = random.Rand(10); i >= 0; i--) {
+      // At least a 1 x 1 updated region.
+      const int left = random.Rand(0, frame->size().width() - 2);
+      const int top = random.Rand(0, frame->size().height() - 2);
+      const int right = random.Rand(left + 1, frame->size().width());
+      const int bottom = random.Rand(top + 1, frame->size().height());
+      frame->mutable_updated_region()->AddRect(
+          DesktopRect::MakeLTRB(left, top, right, bottom));
+    }
+  }
+}
+
+// Paints pixels in |rect| of |frame| to |color|.
+void PaintRect(DesktopFrame* frame, DesktopRect rect, uint32_t color) {
+  static_assert(DesktopFrame::kBytesPerPixel == sizeof(uint32_t),
+                "kBytesPerPixel should be 4.");
+  RTC_DCHECK(frame->size().width() >= rect.right() &&
+             frame->size().height() >= rect.bottom());
+  uint8_t* row = frame->GetFrameDataAtPos(rect.top_left());
+  for (int i = 0; i < rect.height(); i++) {
+    uint32_t* column = reinterpret_cast<uint32_t*>(row);
+    for (int j = 0; j < rect.width(); j++) {
+      column[j] = color;
+    }
+    row += frame->stride();
+  }
+}
+
+// Paints pixels in |region| of |frame| to |color|.
+void PaintRegion(DesktopFrame* frame, DesktopRegion* region, uint32_t color) {
+  region->IntersectWith(DesktopRect::MakeSize(frame->size()));
+  for (DesktopRegion::Iterator it(*region); !it.IsAtEnd(); it.Advance()) {
+    PaintRect(frame, it.rect(), color);
+  }
+}
+
+}  // namespace
+
+DesktopFrameGenerator::DesktopFrameGenerator() {}
+DesktopFrameGenerator::~DesktopFrameGenerator() {}
+
+DesktopFramePainter::DesktopFramePainter() {}
+DesktopFramePainter::~DesktopFramePainter() {}
+
+PainterDesktopFrameGenerator::PainterDesktopFrameGenerator()
+    : size_(1024, 768),
+      return_frame_(true),
+      provide_updated_region_hints_(false),
+      enlarge_updated_region_(false),
+      enlarge_range_(20),
+      add_random_updated_region_(false),
+      painter_(nullptr) {}
+PainterDesktopFrameGenerator::~PainterDesktopFrameGenerator() {}
+
+std::unique_ptr<DesktopFrame> PainterDesktopFrameGenerator::GetNextFrame(
+    SharedMemoryFactory* factory) {
+  if (!return_frame_) {
+    return nullptr;
+  }
+
+  std::unique_ptr<DesktopFrame> frame = std::unique_ptr<DesktopFrame>(
+      factory ? SharedMemoryDesktopFrame::Create(size_, factory).release()
+              : new BasicDesktopFrame(size_));
+  if (painter_) {
+    DesktopRegion updated_region;
+    if (!painter_->Paint(frame.get(), &updated_region)) {
+      return nullptr;
+    }
+
+    if (provide_updated_region_hints_) {
+      SetUpdatedRegion(frame.get(), updated_region, enlarge_updated_region_,
+                       enlarge_range_, add_random_updated_region_);
+    } else {
+      frame->mutable_updated_region()->SetRect(
+          DesktopRect::MakeSize(frame->size()));
+    }
+  }
+
+  return frame;
+}
+
+DesktopSize* PainterDesktopFrameGenerator::size() {
+  return &size_;
+}
+
+void PainterDesktopFrameGenerator::set_return_frame(bool return_frame) {
+  return_frame_ = return_frame;
+}
+
+void PainterDesktopFrameGenerator::set_provide_updated_region_hints(
+    bool provide_updated_region_hints) {
+  provide_updated_region_hints_ = provide_updated_region_hints;
+}
+
+void PainterDesktopFrameGenerator::set_enlarge_updated_region(
+    bool enlarge_updated_region) {
+  enlarge_updated_region_ = enlarge_updated_region;
+}
+
+void PainterDesktopFrameGenerator::set_enlarge_range(int enlarge_range) {
+  enlarge_range_ = enlarge_range;
+}
+
+void PainterDesktopFrameGenerator::set_add_random_updated_region(
+    bool add_random_updated_region) {
+  add_random_updated_region_ = add_random_updated_region;
+}
+
+void PainterDesktopFrameGenerator::set_desktop_frame_painter(
+    DesktopFramePainter* painter) {
+  painter_ = painter;
+}
+
+BlackWhiteDesktopFramePainter::BlackWhiteDesktopFramePainter() {}
+BlackWhiteDesktopFramePainter::~BlackWhiteDesktopFramePainter() {}
+
+DesktopRegion* BlackWhiteDesktopFramePainter::updated_region() {
+  return &updated_region_;
+}
+
+bool BlackWhiteDesktopFramePainter::Paint(DesktopFrame* frame,
+                                          DesktopRegion* updated_region) {
+  RTC_DCHECK(updated_region->is_empty());
+  memset(frame->data(), 0, frame->stride() * frame->size().height());
+  PaintRegion(frame, &updated_region_, UINT32_MAX);
+  updated_region_.Swap(updated_region);
+  return true;
+}
+
+}  // namespace webrtc