modules/desktop_capture/mac/screen_capturer_mac.mm - src - Git at Google

 /*
  *  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.
  */

 #include <utility>

 #include "modules/desktop_capture/mac/screen_capturer_mac.h"

 #include "modules/desktop_capture/mac/desktop_frame_provider.h"
 #include "modules/desktop_capture/mac/window_list_utils.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/time_utils.h"
 #include "rtc_base/trace_event.h"
 #include "sdk/objc/helpers/scoped_cftyperef.h"

 namespace webrtc {

 namespace {

 // Scales all coordinates of a rect by a specified factor.
 DesktopRect ScaleAndRoundCGRect(const CGRect& rect, float scale) {
   return DesktopRect::MakeLTRB(static_cast<int>(floor(rect.origin.x * scale)),
                                static_cast<int>(floor(rect.origin.y * scale)),
                                static_cast<int>(ceil((rect.origin.x + rect.size.width) * scale)),
                                static_cast<int>(ceil((rect.origin.y + rect.size.height) * scale)));
 }

 // Copy pixels in the `rect` from `src_place` to `dest_plane`. `rect` should be
 // relative to the origin of `src_plane` and `dest_plane`.
 void CopyRect(const uint8_t* src_plane,
               int src_plane_stride,
               uint8_t* dest_plane,
               int dest_plane_stride,
               int bytes_per_pixel,
               const DesktopRect& rect) {
   // Get the address of the starting point.
   const int src_y_offset = src_plane_stride * rect.top();
   const int dest_y_offset = dest_plane_stride * rect.top();
   const int x_offset = bytes_per_pixel * rect.left();
   src_plane += src_y_offset + x_offset;
   dest_plane += dest_y_offset + x_offset;

   // Copy pixels in the rectangle line by line.
   const int bytes_per_line = bytes_per_pixel * rect.width();
   const int height = rect.height();
   for (int i = 0; i < height; ++i) {
     memcpy(dest_plane, src_plane, bytes_per_line);
     src_plane += src_plane_stride;
     dest_plane += dest_plane_stride;
   }
 }

 // Returns an array of CGWindowID for all the on-screen windows except
 // `window_to_exclude`, or NULL if the window is not found or it fails. The
 // caller should release the returned CFArrayRef.
 CFArrayRef CreateWindowListWithExclusion(CGWindowID window_to_exclude) {
   if (!window_to_exclude) return nullptr;

   CFArrayRef all_windows =
       CGWindowListCopyWindowInfo(kCGWindowListOptionOnScreenOnly, kCGNullWindowID);
   if (!all_windows) return nullptr;

   CFMutableArrayRef returned_array =
       CFArrayCreateMutable(nullptr, CFArrayGetCount(all_windows), nullptr);

   bool found = false;
   for (CFIndex i = 0; i < CFArrayGetCount(all_windows); ++i) {
     CFDictionaryRef window =
         reinterpret_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(all_windows, i));

     CGWindowID id = GetWindowId(window);
     if (id == window_to_exclude) {
       found = true;
       continue;
     }
     CFArrayAppendValue(returned_array, reinterpret_cast<void*>(id));
   }
   CFRelease(all_windows);

   if (!found) {
     CFRelease(returned_array);
     returned_array = nullptr;
   }
   return returned_array;
 }

 // Returns the bounds of `window` in physical pixels, enlarged by a small amount
 // on four edges to take account of the border/shadow effects.
 DesktopRect GetExcludedWindowPixelBounds(CGWindowID window, float dip_to_pixel_scale) {
   // The amount of pixels to add to the actual window bounds to take into
   // account of the border/shadow effects.
   static const int kBorderEffectSize = 20;
   CGRect rect;
   CGWindowID ids[1];
   ids[0] = window;

   CFArrayRef window_id_array =
       CFArrayCreate(nullptr, reinterpret_cast<const void**>(&ids), 1, nullptr);
   CFArrayRef window_array = CGWindowListCreateDescriptionFromArray(window_id_array);

   if (CFArrayGetCount(window_array) > 0) {
     CFDictionaryRef win =
         reinterpret_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(window_array, 0));
     CFDictionaryRef bounds_ref =
         reinterpret_cast<CFDictionaryRef>(CFDictionaryGetValue(win, kCGWindowBounds));
     CGRectMakeWithDictionaryRepresentation(bounds_ref, &rect);
   }

   CFRelease(window_id_array);
   CFRelease(window_array);

   rect.origin.x -= kBorderEffectSize;
   rect.origin.y -= kBorderEffectSize;
   rect.size.width += kBorderEffectSize * 2;
   rect.size.height += kBorderEffectSize * 2;
   // `rect` is in DIP, so convert to physical pixels.
   return ScaleAndRoundCGRect(rect, dip_to_pixel_scale);
 }

 // Create an image of the given region using the given `window_list`.
 // `pixel_bounds` should be in the primary display's coordinate in physical
 // pixels.
 rtc::ScopedCFTypeRef<CGImageRef> CreateExcludedWindowRegionImage(const DesktopRect& pixel_bounds,
                                                                  float dip_to_pixel_scale,
                                                                  CFArrayRef window_list) {
   CGRect window_bounds;
   // The origin is in DIP while the size is in physical pixels. That's what
   // CGWindowListCreateImageFromArray expects.
   window_bounds.origin.x = pixel_bounds.left() / dip_to_pixel_scale;
   window_bounds.origin.y = pixel_bounds.top() / dip_to_pixel_scale;
   window_bounds.size.width = pixel_bounds.width();
   window_bounds.size.height = pixel_bounds.height();

   return rtc::ScopedCFTypeRef<CGImageRef>(
       CGWindowListCreateImageFromArray(window_bounds, window_list, kCGWindowImageDefault));
 }

 }  // namespace

 ScreenCapturerMac::ScreenCapturerMac(
     rtc::scoped_refptr<DesktopConfigurationMonitor> desktop_config_monitor,
     bool detect_updated_region,
     bool allow_iosurface)
     : detect_updated_region_(detect_updated_region),
       desktop_config_monitor_(desktop_config_monitor),
       desktop_frame_provider_(allow_iosurface) {
   RTC_LOG(LS_INFO) << "Allow IOSurface: " << allow_iosurface;
   thread_checker_.Detach();
 }

 ScreenCapturerMac::~ScreenCapturerMac() {
   RTC_DCHECK(thread_checker_.IsCurrent());
   ReleaseBuffers();
   UnregisterRefreshAndMoveHandlers();
 }

 bool ScreenCapturerMac::Init() {
   TRACE_EVENT0("webrtc", "ScreenCapturerMac::Init");
   desktop_config_ = desktop_config_monitor_->desktop_configuration();
   return true;
 }

 void ScreenCapturerMac::ReleaseBuffers() {
   // The buffers might be in use by the encoder, so don't delete them here.
   // Instead, mark them as "needs update"; next time the buffers are used by
   // the capturer, they will be recreated if necessary.
   queue_.Reset();
 }

 void ScreenCapturerMac::Start(Callback* callback) {
   RTC_DCHECK(thread_checker_.IsCurrent());
   RTC_DCHECK(!callback_);
   RTC_DCHECK(callback);
   TRACE_EVENT_INSTANT1(
       "webrtc", "ScreenCapturermac::Start", "target display id ", current_display_);

   callback_ = callback;
   // Start and operate CGDisplayStream handler all from capture thread.
   if (!RegisterRefreshAndMoveHandlers()) {
     RTC_LOG(LS_ERROR) << "Failed to register refresh and move handlers.";
     callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
     return;
   }
   ScreenConfigurationChanged();
 }

 void ScreenCapturerMac::CaptureFrame() {
   RTC_DCHECK(thread_checker_.IsCurrent());
   TRACE_EVENT0("webrtc", "creenCapturerMac::CaptureFrame");
   int64_t capture_start_time_nanos = rtc::TimeNanos();

   queue_.MoveToNextFrame();
   if (queue_.current_frame() && queue_.current_frame()->IsShared()) {
     RTC_DLOG(LS_WARNING) << "Overwriting frame that is still shared.";
   }

   MacDesktopConfiguration new_config = desktop_config_monitor_->desktop_configuration();
   if (!desktop_config_.Equals(new_config)) {
     desktop_config_ = new_config;
     // If the display configuraiton has changed then refresh capturer data
     // structures. Occasionally, the refresh and move handlers are lost when
     // the screen mode changes, so re-register them here.
     UnregisterRefreshAndMoveHandlers();
     if (!RegisterRefreshAndMoveHandlers()) {
       RTC_LOG(LS_ERROR) << "Failed to register refresh and move handlers.";
       callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
       return;
     }
     ScreenConfigurationChanged();
   }

   // When screen is zoomed in/out, OSX only updates the part of Rects currently
   // displayed on screen, with relative location to current top-left on screen.
   // This will cause problems when we copy the dirty regions to the captured
   // image. So we invalidate the whole screen to copy all the screen contents.
   // With CGI method, the zooming will be ignored and the whole screen contents
   // will be captured as before.
   // With IOSurface method, the zoomed screen contents will be captured.
   if (UAZoomEnabled()) {
     helper_.InvalidateScreen(screen_pixel_bounds_.size());
   }

   DesktopRegion region;
   helper_.TakeInvalidRegion(&region);

   // If the current buffer is from an older generation then allocate a new one.
   // Note that we can't reallocate other buffers at this point, since the caller
   // may still be reading from them.
   if (!queue_.current_frame()) queue_.ReplaceCurrentFrame(SharedDesktopFrame::Wrap(CreateFrame()));

   DesktopFrame* current_frame = queue_.current_frame();

   if (!CgBlit(*current_frame, region)) {
     callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
     return;
   }
   std::unique_ptr<DesktopFrame> new_frame = queue_.current_frame()->Share();
   if (detect_updated_region_) {
     *new_frame->mutable_updated_region() = region;
   } else {
     new_frame->mutable_updated_region()->AddRect(DesktopRect::MakeSize(new_frame->size()));
   }

   if (current_display_) {
     const MacDisplayConfiguration* config =
         desktop_config_.FindDisplayConfigurationById(current_display_);
     if (config) {
       new_frame->set_top_left(
           config->bounds.top_left().subtract(desktop_config_.bounds.top_left()));
     }
   }

   helper_.set_size_most_recent(new_frame->size());

   new_frame->set_capture_time_ms((rtc::TimeNanos() - capture_start_time_nanos) /
                                  rtc::kNumNanosecsPerMillisec);
   callback_->OnCaptureResult(Result::SUCCESS, std::move(new_frame));
 }

 void ScreenCapturerMac::SetExcludedWindow(WindowId window) {
   excluded_window_ = window;
 }

 bool ScreenCapturerMac::GetSourceList(SourceList* screens) {
   RTC_DCHECK(screens->size() == 0);

   for (MacDisplayConfigurations::iterator it = desktop_config_.displays.begin();
        it != desktop_config_.displays.end();
        ++it) {
     screens->push_back({it->id, std::string()});
   }
   return true;
 }

 bool ScreenCapturerMac::SelectSource(SourceId id) {
   if (id == kFullDesktopScreenId) {
     current_display_ = 0;
   } else {
     const MacDisplayConfiguration* config =
         desktop_config_.FindDisplayConfigurationById(static_cast<CGDirectDisplayID>(id));
     if (!config) return false;
     current_display_ = config->id;
   }

   ScreenConfigurationChanged();
   return true;
 }

 bool ScreenCapturerMac::CgBlit(const DesktopFrame& frame, const DesktopRegion& region) {
   // If not all screen region is dirty, copy the entire contents of the previous capture buffer,
   // to capture over.
   if (queue_.previous_frame() && !region.Equals(DesktopRegion(screen_pixel_bounds_))) {
     memcpy(frame.data(), queue_.previous_frame()->data(), frame.stride() * frame.size().height());
   }

   MacDisplayConfigurations displays_to_capture;
   if (current_display_) {
     // Capturing a single screen. Note that the screen id may change when
     // screens are added or removed.
     const MacDisplayConfiguration* config =
         desktop_config_.FindDisplayConfigurationById(current_display_);
     if (config) {
       displays_to_capture.push_back(*config);
     } else {
       RTC_LOG(LS_ERROR) << "The selected screen cannot be found for capturing.";
       return false;
     }
   } else {
     // Capturing the whole desktop.
     displays_to_capture = desktop_config_.displays;
   }

   // Create the window list once for all displays.
   CFArrayRef window_list = CreateWindowListWithExclusion(excluded_window_);

   for (size_t i = 0; i < displays_to_capture.size(); ++i) {
     const MacDisplayConfiguration& display_config = displays_to_capture[i];

     // Capturing mixed-DPI on one surface is hard, so we only return displays
     // that match the "primary" display's DPI. The primary display is always
     // the first in the list.
     if (i > 0 && display_config.dip_to_pixel_scale != displays_to_capture[0].dip_to_pixel_scale) {
       continue;
     }
     // Determine the display's position relative to the desktop, in pixels.
     DesktopRect display_bounds = display_config.pixel_bounds;
     display_bounds.Translate(-screen_pixel_bounds_.left(), -screen_pixel_bounds_.top());

     // Determine which parts of the blit region, if any, lay within the monitor.
     DesktopRegion copy_region = region;
     copy_region.IntersectWith(display_bounds);
     if (copy_region.is_empty()) continue;

     // Translate the region to be copied into display-relative coordinates.
     copy_region.Translate(-display_bounds.left(), -display_bounds.top());

     DesktopRect excluded_window_bounds;
     rtc::ScopedCFTypeRef<CGImageRef> excluded_image;
     if (excluded_window_ && window_list) {
       // Get the region of the excluded window relative the primary display.
       excluded_window_bounds =
           GetExcludedWindowPixelBounds(excluded_window_, display_config.dip_to_pixel_scale);
       excluded_window_bounds.IntersectWith(display_config.pixel_bounds);

       // Create the image under the excluded window first, because it's faster
       // than captuing the whole display.
       if (!excluded_window_bounds.is_empty()) {
         excluded_image = CreateExcludedWindowRegionImage(
             excluded_window_bounds, display_config.dip_to_pixel_scale, window_list);
       }
     }

     std::unique_ptr<DesktopFrame> frame_source =
         desktop_frame_provider_.TakeLatestFrameForDisplay(display_config.id);
     if (!frame_source) {
       continue;
     }

     const uint8_t* display_base_address = frame_source->data();
     int src_bytes_per_row = frame_source->stride();
     RTC_DCHECK(display_base_address);

     // `frame_source` size may be different from display_bounds in case the screen was
     // resized recently.
     copy_region.IntersectWith(frame_source->rect());

     // Copy the dirty region from the display buffer into our desktop buffer.
     uint8_t* out_ptr = frame.GetFrameDataAtPos(display_bounds.top_left());
     for (DesktopRegion::Iterator it(copy_region); !it.IsAtEnd(); it.Advance()) {
       CopyRect(display_base_address,
                src_bytes_per_row,
                out_ptr,
                frame.stride(),
                DesktopFrame::kBytesPerPixel,
                it.rect());
     }

     if (excluded_image) {
       CGDataProviderRef provider = CGImageGetDataProvider(excluded_image.get());
       rtc::ScopedCFTypeRef<CFDataRef> excluded_image_data(CGDataProviderCopyData(provider));
       RTC_DCHECK(excluded_image_data);
       display_base_address = CFDataGetBytePtr(excluded_image_data.get());
       src_bytes_per_row = CGImageGetBytesPerRow(excluded_image.get());

       // Translate the bounds relative to the desktop, because `frame` data
       // starts from the desktop top-left corner.
       DesktopRect window_bounds_relative_to_desktop(excluded_window_bounds);
       window_bounds_relative_to_desktop.Translate(-screen_pixel_bounds_.left(),
                                                   -screen_pixel_bounds_.top());

       DesktopRect rect_to_copy = DesktopRect::MakeSize(excluded_window_bounds.size());
       rect_to_copy.IntersectWith(DesktopRect::MakeWH(CGImageGetWidth(excluded_image.get()),
                                                      CGImageGetHeight(excluded_image.get())));

       if (CGImageGetBitsPerPixel(excluded_image.get()) / 8 == DesktopFrame::kBytesPerPixel) {
         CopyRect(display_base_address,
                  src_bytes_per_row,
                  frame.GetFrameDataAtPos(window_bounds_relative_to_desktop.top_left()),
                  frame.stride(),
                  DesktopFrame::kBytesPerPixel,
                  rect_to_copy);
       }
     }
   }
   if (window_list) CFRelease(window_list);
   return true;
 }

 void ScreenCapturerMac::ScreenConfigurationChanged() {
   if (current_display_) {
     const MacDisplayConfiguration* config =
         desktop_config_.FindDisplayConfigurationById(current_display_);
     screen_pixel_bounds_ = config ? config->pixel_bounds : DesktopRect();
     dip_to_pixel_scale_ = config ? config->dip_to_pixel_scale : 1.0f;
   } else {
     screen_pixel_bounds_ = desktop_config_.pixel_bounds;
     dip_to_pixel_scale_ = desktop_config_.dip_to_pixel_scale;
   }

   // Release existing buffers, which will be of the wrong size.
   ReleaseBuffers();

   // Clear the dirty region, in case the display is down-sizing.
   helper_.ClearInvalidRegion();

   // Re-mark the entire desktop as dirty.
   helper_.InvalidateScreen(screen_pixel_bounds_.size());

   // Make sure the frame buffers will be reallocated.
   queue_.Reset();
 }

 bool ScreenCapturerMac::RegisterRefreshAndMoveHandlers() {
   RTC_DCHECK(thread_checker_.IsCurrent());
   desktop_config_ = desktop_config_monitor_->desktop_configuration();
   for (const auto& config : desktop_config_.displays) {
     size_t pixel_width = config.pixel_bounds.width();
     size_t pixel_height = config.pixel_bounds.height();
     if (pixel_width == 0 || pixel_height == 0) continue;
     CGDirectDisplayID display_id = config.id;
     DesktopVector display_origin = config.pixel_bounds.top_left();

     CGDisplayStreamFrameAvailableHandler handler = ^(CGDisplayStreamFrameStatus status,
                                                      uint64_t display_time,
                                                      IOSurfaceRef frame_surface,
                                                      CGDisplayStreamUpdateRef updateRef) {
       RTC_DCHECK(thread_checker_.IsCurrent());
       if (status == kCGDisplayStreamFrameStatusStopped) return;

       // Only pay attention to frame updates.
       if (status != kCGDisplayStreamFrameStatusFrameComplete) return;

       size_t count = 0;
       const CGRect* rects =
           CGDisplayStreamUpdateGetRects(updateRef, kCGDisplayStreamUpdateDirtyRects, &count);
       if (count != 0) {
         // According to CGDisplayStream.h, it's safe to call
         // CGDisplayStreamStop() from within the callback.
         ScreenRefresh(display_id, count, rects, display_origin, frame_surface);
       }
     };

     rtc::ScopedCFTypeRef<CFDictionaryRef> properties_dict(
         CFDictionaryCreate(kCFAllocatorDefault,
                            (const void*[]){kCGDisplayStreamShowCursor},
                            (const void*[]){kCFBooleanFalse},
                            1,
                            &kCFTypeDictionaryKeyCallBacks,
                            &kCFTypeDictionaryValueCallBacks));

     CGDisplayStreamRef display_stream = CGDisplayStreamCreate(
         display_id, pixel_width, pixel_height, 'BGRA', properties_dict.get(), handler);

     if (display_stream) {
       CGError error = CGDisplayStreamStart(display_stream);
       if (error != kCGErrorSuccess) return false;

       CFRunLoopSourceRef source = CGDisplayStreamGetRunLoopSource(display_stream);
       CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopCommonModes);
       display_streams_.push_back(display_stream);
     }
   }

   return true;
 }

 void ScreenCapturerMac::UnregisterRefreshAndMoveHandlers() {
   RTC_DCHECK(thread_checker_.IsCurrent());

   for (CGDisplayStreamRef stream : display_streams_) {
     CFRunLoopSourceRef source = CGDisplayStreamGetRunLoopSource(stream);
     CFRunLoopRemoveSource(CFRunLoopGetCurrent(), source, kCFRunLoopCommonModes);
     CGDisplayStreamStop(stream);
     CFRelease(stream);
   }
   display_streams_.clear();

   // Release obsolete io surfaces.
   desktop_frame_provider_.Release();
 }

 void ScreenCapturerMac::ScreenRefresh(CGDirectDisplayID display_id,
                                       CGRectCount count,
                                       const CGRect* rect_array,
                                       DesktopVector display_origin,
                                       IOSurfaceRef io_surface) {
   if (screen_pixel_bounds_.is_empty()) ScreenConfigurationChanged();

   // The refresh rects are in display coordinates. We want to translate to
   // framebuffer coordinates. If a specific display is being captured, then no
   // change is necessary. If all displays are being captured, then we want to
   // translate by the origin of the display.
   DesktopVector translate_vector;
   if (!current_display_) translate_vector = display_origin;

   DesktopRegion region;
   for (CGRectCount i = 0; i < count; ++i) {
     // All rects are already in physical pixel coordinates.
     DesktopRect rect = DesktopRect::MakeXYWH(rect_array[i].origin.x,
                                              rect_array[i].origin.y,
                                              rect_array[i].size.width,
                                              rect_array[i].size.height);

     rect.Translate(translate_vector);

     region.AddRect(rect);
   }
   // Always having the latest iosurface before invalidating a region.
   // See https://bugs.chromium.org/p/webrtc/issues/detail?id=8652 for details.
   desktop_frame_provider_.InvalidateIOSurface(
       display_id, rtc::ScopedCFTypeRef<IOSurfaceRef>(io_surface, rtc::RetainPolicy::RETAIN));
   helper_.InvalidateRegion(region);
 }

 std::unique_ptr<DesktopFrame> ScreenCapturerMac::CreateFrame() {
   std::unique_ptr<DesktopFrame> frame(new BasicDesktopFrame(screen_pixel_bounds_.size()));
   frame->set_dpi(
       DesktopVector(kStandardDPI * dip_to_pixel_scale_, kStandardDPI * dip_to_pixel_scale_));
   return frame;
 }

 }  // namespace webrtc
	/*
	* 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.
	*/

	#include <utility>

	#include "modules/desktop_capture/mac/screen_capturer_mac.h"

	#include "modules/desktop_capture/mac/desktop_frame_provider.h"
	#include "modules/desktop_capture/mac/window_list_utils.h"
	#include "rtc_base/checks.h"
	#include "rtc_base/logging.h"
	#include "rtc_base/time_utils.h"
	#include "rtc_base/trace_event.h"
	#include "sdk/objc/helpers/scoped_cftyperef.h"

	namespace webrtc {

	namespace {

	// Scales all coordinates of a rect by a specified factor.
	DesktopRect ScaleAndRoundCGRect(const CGRect& rect, float scale) {
	return DesktopRect::MakeLTRB(static_cast<int>(floor(rect.origin.x * scale)),
	static_cast<int>(floor(rect.origin.y * scale)),
	static_cast<int>(ceil((rect.origin.x + rect.size.width) * scale)),
	static_cast<int>(ceil((rect.origin.y + rect.size.height) * scale)));
	}

	// Copy pixels in the `rect` from `src_place` to `dest_plane`. `rect` should be
	// relative to the origin of `src_plane` and `dest_plane`.
	void CopyRect(const uint8_t* src_plane,
	int src_plane_stride,
	uint8_t* dest_plane,
	int dest_plane_stride,
	int bytes_per_pixel,
	const DesktopRect& rect) {
	// Get the address of the starting point.
	const int src_y_offset = src_plane_stride * rect.top();
	const int dest_y_offset = dest_plane_stride * rect.top();
	const int x_offset = bytes_per_pixel * rect.left();
	src_plane += src_y_offset + x_offset;
	dest_plane += dest_y_offset + x_offset;

	// Copy pixels in the rectangle line by line.
	const int bytes_per_line = bytes_per_pixel * rect.width();
	const int height = rect.height();
	for (int i = 0; i < height; ++i) {
	memcpy(dest_plane, src_plane, bytes_per_line);
	src_plane += src_plane_stride;
	dest_plane += dest_plane_stride;
	}
	}

	// Returns an array of CGWindowID for all the on-screen windows except
	// `window_to_exclude`, or NULL if the window is not found or it fails. The
	// caller should release the returned CFArrayRef.
	CFArrayRef CreateWindowListWithExclusion(CGWindowID window_to_exclude) {
	if (!window_to_exclude) return nullptr;

	CFArrayRef all_windows =
	CGWindowListCopyWindowInfo(kCGWindowListOptionOnScreenOnly, kCGNullWindowID);
	if (!all_windows) return nullptr;

	CFMutableArrayRef returned_array =
	CFArrayCreateMutable(nullptr, CFArrayGetCount(all_windows), nullptr);

	bool found = false;
	for (CFIndex i = 0; i < CFArrayGetCount(all_windows); ++i) {
	CFDictionaryRef window =
	reinterpret_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(all_windows, i));

	CGWindowID id = GetWindowId(window);
	if (id == window_to_exclude) {
	found = true;
	continue;
	}
	CFArrayAppendValue(returned_array, reinterpret_cast<void*>(id));
	}
	CFRelease(all_windows);

	if (!found) {
	CFRelease(returned_array);
	returned_array = nullptr;
	}
	return returned_array;
	}

	// Returns the bounds of `window` in physical pixels, enlarged by a small amount
	// on four edges to take account of the border/shadow effects.
	DesktopRect GetExcludedWindowPixelBounds(CGWindowID window, float dip_to_pixel_scale) {
	// The amount of pixels to add to the actual window bounds to take into
	// account of the border/shadow effects.
	static const int kBorderEffectSize = 20;
	CGRect rect;
	CGWindowID ids[1];
	ids[0] = window;

	CFArrayRef window_id_array =
	CFArrayCreate(nullptr, reinterpret_cast<const void**>(&ids), 1, nullptr);
	CFArrayRef window_array = CGWindowListCreateDescriptionFromArray(window_id_array);

	if (CFArrayGetCount(window_array) > 0) {
	CFDictionaryRef win =
	reinterpret_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(window_array, 0));
	CFDictionaryRef bounds_ref =
	reinterpret_cast<CFDictionaryRef>(CFDictionaryGetValue(win, kCGWindowBounds));
	CGRectMakeWithDictionaryRepresentation(bounds_ref, &rect);
	}

	CFRelease(window_id_array);
	CFRelease(window_array);

	rect.origin.x -= kBorderEffectSize;
	rect.origin.y -= kBorderEffectSize;
	rect.size.width += kBorderEffectSize * 2;
	rect.size.height += kBorderEffectSize * 2;
	// `rect` is in DIP, so convert to physical pixels.
	return ScaleAndRoundCGRect(rect, dip_to_pixel_scale);
	}

	// Create an image of the given region using the given `window_list`.
	// `pixel_bounds` should be in the primary display's coordinate in physical
	// pixels.
	rtc::ScopedCFTypeRef<CGImageRef> CreateExcludedWindowRegionImage(const DesktopRect& pixel_bounds,
	float dip_to_pixel_scale,
	CFArrayRef window_list) {
	CGRect window_bounds;
	// The origin is in DIP while the size is in physical pixels. That's what
	// CGWindowListCreateImageFromArray expects.
	window_bounds.origin.x = pixel_bounds.left() / dip_to_pixel_scale;
	window_bounds.origin.y = pixel_bounds.top() / dip_to_pixel_scale;
	window_bounds.size.width = pixel_bounds.width();
	window_bounds.size.height = pixel_bounds.height();

	return rtc::ScopedCFTypeRef<CGImageRef>(
	CGWindowListCreateImageFromArray(window_bounds, window_list, kCGWindowImageDefault));
	}

	} // namespace

	ScreenCapturerMac::ScreenCapturerMac(
	rtc::scoped_refptr<DesktopConfigurationMonitor> desktop_config_monitor,
	bool detect_updated_region,
	bool allow_iosurface)
	: detect_updated_region_(detect_updated_region),
	desktop_config_monitor_(desktop_config_monitor),
	desktop_frame_provider_(allow_iosurface) {
	RTC_LOG(LS_INFO) << "Allow IOSurface: " << allow_iosurface;
	thread_checker_.Detach();
	}

	ScreenCapturerMac::~ScreenCapturerMac() {
	RTC_DCHECK(thread_checker_.IsCurrent());
	ReleaseBuffers();
	UnregisterRefreshAndMoveHandlers();
	}

	bool ScreenCapturerMac::Init() {
	TRACE_EVENT0("webrtc", "ScreenCapturerMac::Init");
	desktop_config_ = desktop_config_monitor_->desktop_configuration();
	return true;
	}

	void ScreenCapturerMac::ReleaseBuffers() {
	// The buffers might be in use by the encoder, so don't delete them here.
	// Instead, mark them as "needs update"; next time the buffers are used by
	// the capturer, they will be recreated if necessary.
	queue_.Reset();
	}

	void ScreenCapturerMac::Start(Callback* callback) {
	RTC_DCHECK(thread_checker_.IsCurrent());
	RTC_DCHECK(!callback_);
	RTC_DCHECK(callback);
	TRACE_EVENT_INSTANT1(
	"webrtc", "ScreenCapturermac::Start", "target display id ", current_display_);

	callback_ = callback;
	// Start and operate CGDisplayStream handler all from capture thread.
	if (!RegisterRefreshAndMoveHandlers()) {
	RTC_LOG(LS_ERROR) << "Failed to register refresh and move handlers.";
	callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
	return;
	}
	ScreenConfigurationChanged();
	}

	void ScreenCapturerMac::CaptureFrame() {
	RTC_DCHECK(thread_checker_.IsCurrent());
	TRACE_EVENT0("webrtc", "creenCapturerMac::CaptureFrame");
	int64_t capture_start_time_nanos = rtc::TimeNanos();

	queue_.MoveToNextFrame();
	if (queue_.current_frame() && queue_.current_frame()->IsShared()) {
	RTC_DLOG(LS_WARNING) << "Overwriting frame that is still shared.";
	}

	MacDesktopConfiguration new_config = desktop_config_monitor_->desktop_configuration();
	if (!desktop_config_.Equals(new_config)) {
	desktop_config_ = new_config;
	// If the display configuraiton has changed then refresh capturer data
	// structures. Occasionally, the refresh and move handlers are lost when
	// the screen mode changes, so re-register them here.
	UnregisterRefreshAndMoveHandlers();
	if (!RegisterRefreshAndMoveHandlers()) {
	RTC_LOG(LS_ERROR) << "Failed to register refresh and move handlers.";
	callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
	return;
	}
	ScreenConfigurationChanged();
	}

	// When screen is zoomed in/out, OSX only updates the part of Rects currently
	// displayed on screen, with relative location to current top-left on screen.
	// This will cause problems when we copy the dirty regions to the captured
	// image. So we invalidate the whole screen to copy all the screen contents.
	// With CGI method, the zooming will be ignored and the whole screen contents
	// will be captured as before.
	// With IOSurface method, the zoomed screen contents will be captured.
	if (UAZoomEnabled()) {
	helper_.InvalidateScreen(screen_pixel_bounds_.size());
	}

	DesktopRegion region;
	helper_.TakeInvalidRegion(&region);

	// If the current buffer is from an older generation then allocate a new one.
	// Note that we can't reallocate other buffers at this point, since the caller
	// may still be reading from them.
	if (!queue_.current_frame()) queue_.ReplaceCurrentFrame(SharedDesktopFrame::Wrap(CreateFrame()));

	DesktopFrame* current_frame = queue_.current_frame();

	if (!CgBlit(*current_frame, region)) {
	callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
	return;
	}
	std::unique_ptr<DesktopFrame> new_frame = queue_.current_frame()->Share();
	if (detect_updated_region_) {
	*new_frame->mutable_updated_region() = region;
	} else {
	new_frame->mutable_updated_region()->AddRect(DesktopRect::MakeSize(new_frame->size()));
	}

	if (current_display_) {
	const MacDisplayConfiguration* config =
	desktop_config_.FindDisplayConfigurationById(current_display_);
	if (config) {
	new_frame->set_top_left(
	config->bounds.top_left().subtract(desktop_config_.bounds.top_left()));
	}
	}

	helper_.set_size_most_recent(new_frame->size());

	new_frame->set_capture_time_ms((rtc::TimeNanos() - capture_start_time_nanos) /
	rtc::kNumNanosecsPerMillisec);
	callback_->OnCaptureResult(Result::SUCCESS, std::move(new_frame));
	}

	void ScreenCapturerMac::SetExcludedWindow(WindowId window) {
	excluded_window_ = window;
	}

	bool ScreenCapturerMac::GetSourceList(SourceList* screens) {
	RTC_DCHECK(screens->size() == 0);

	for (MacDisplayConfigurations::iterator it = desktop_config_.displays.begin();
	it != desktop_config_.displays.end();
	++it) {
	screens->push_back({it->id, std::string()});
	}
	return true;
	}

	bool ScreenCapturerMac::SelectSource(SourceId id) {
	if (id == kFullDesktopScreenId) {
	current_display_ = 0;
	} else {
	const MacDisplayConfiguration* config =
	desktop_config_.FindDisplayConfigurationById(static_cast<CGDirectDisplayID>(id));
	if (!config) return false;
	current_display_ = config->id;
	}

	ScreenConfigurationChanged();
	return true;
	}

	bool ScreenCapturerMac::CgBlit(const DesktopFrame& frame, const DesktopRegion& region) {
	// If not all screen region is dirty, copy the entire contents of the previous capture buffer,
	// to capture over.
	if (queue_.previous_frame() && !region.Equals(DesktopRegion(screen_pixel_bounds_))) {
	memcpy(frame.data(), queue_.previous_frame()->data(), frame.stride() * frame.size().height());
	}

	MacDisplayConfigurations displays_to_capture;
	if (current_display_) {
	// Capturing a single screen. Note that the screen id may change when
	// screens are added or removed.
	const MacDisplayConfiguration* config =
	desktop_config_.FindDisplayConfigurationById(current_display_);
	if (config) {
	displays_to_capture.push_back(*config);
	} else {
	RTC_LOG(LS_ERROR) << "The selected screen cannot be found for capturing.";
	return false;
	}
	} else {
	// Capturing the whole desktop.
	displays_to_capture = desktop_config_.displays;
	}

	// Create the window list once for all displays.
	CFArrayRef window_list = CreateWindowListWithExclusion(excluded_window_);

	for (size_t i = 0; i < displays_to_capture.size(); ++i) {
	const MacDisplayConfiguration& display_config = displays_to_capture[i];

	// Capturing mixed-DPI on one surface is hard, so we only return displays
	// that match the "primary" display's DPI. The primary display is always
	// the first in the list.
	if (i > 0 && display_config.dip_to_pixel_scale != displays_to_capture[0].dip_to_pixel_scale) {
	continue;
	}
	// Determine the display's position relative to the desktop, in pixels.
	DesktopRect display_bounds = display_config.pixel_bounds;
	display_bounds.Translate(-screen_pixel_bounds_.left(), -screen_pixel_bounds_.top());

	// Determine which parts of the blit region, if any, lay within the monitor.
	DesktopRegion copy_region = region;
	copy_region.IntersectWith(display_bounds);
	if (copy_region.is_empty()) continue;

	// Translate the region to be copied into display-relative coordinates.
	copy_region.Translate(-display_bounds.left(), -display_bounds.top());

	DesktopRect excluded_window_bounds;
	rtc::ScopedCFTypeRef<CGImageRef> excluded_image;
	if (excluded_window_ && window_list) {
	// Get the region of the excluded window relative the primary display.
	excluded_window_bounds =
	GetExcludedWindowPixelBounds(excluded_window_, display_config.dip_to_pixel_scale);
	excluded_window_bounds.IntersectWith(display_config.pixel_bounds);

	// Create the image under the excluded window first, because it's faster
	// than captuing the whole display.
	if (!excluded_window_bounds.is_empty()) {
	excluded_image = CreateExcludedWindowRegionImage(
	excluded_window_bounds, display_config.dip_to_pixel_scale, window_list);
	}
	}

	std::unique_ptr<DesktopFrame> frame_source =
	desktop_frame_provider_.TakeLatestFrameForDisplay(display_config.id);
	if (!frame_source) {
	continue;
	}

	const uint8_t* display_base_address = frame_source->data();
	int src_bytes_per_row = frame_source->stride();
	RTC_DCHECK(display_base_address);

	// `frame_source` size may be different from display_bounds in case the screen was
	// resized recently.
	copy_region.IntersectWith(frame_source->rect());

	// Copy the dirty region from the display buffer into our desktop buffer.
	uint8_t* out_ptr = frame.GetFrameDataAtPos(display_bounds.top_left());
	for (DesktopRegion::Iterator it(copy_region); !it.IsAtEnd(); it.Advance()) {
	CopyRect(display_base_address,
	src_bytes_per_row,
	out_ptr,
	frame.stride(),
	DesktopFrame::kBytesPerPixel,
	it.rect());
	}

	if (excluded_image) {
	CGDataProviderRef provider = CGImageGetDataProvider(excluded_image.get());
	rtc::ScopedCFTypeRef<CFDataRef> excluded_image_data(CGDataProviderCopyData(provider));
	RTC_DCHECK(excluded_image_data);
	display_base_address = CFDataGetBytePtr(excluded_image_data.get());
	src_bytes_per_row = CGImageGetBytesPerRow(excluded_image.get());

	// Translate the bounds relative to the desktop, because `frame` data
	// starts from the desktop top-left corner.
	DesktopRect window_bounds_relative_to_desktop(excluded_window_bounds);
	window_bounds_relative_to_desktop.Translate(-screen_pixel_bounds_.left(),
	-screen_pixel_bounds_.top());

	DesktopRect rect_to_copy = DesktopRect::MakeSize(excluded_window_bounds.size());
	rect_to_copy.IntersectWith(DesktopRect::MakeWH(CGImageGetWidth(excluded_image.get()),
	CGImageGetHeight(excluded_image.get())));

	if (CGImageGetBitsPerPixel(excluded_image.get()) / 8 == DesktopFrame::kBytesPerPixel) {
	CopyRect(display_base_address,
	src_bytes_per_row,
	frame.GetFrameDataAtPos(window_bounds_relative_to_desktop.top_left()),
	frame.stride(),
	DesktopFrame::kBytesPerPixel,
	rect_to_copy);
	}
	}
	}
	if (window_list) CFRelease(window_list);
	return true;
	}

	void ScreenCapturerMac::ScreenConfigurationChanged() {
	if (current_display_) {
	const MacDisplayConfiguration* config =
	desktop_config_.FindDisplayConfigurationById(current_display_);
	screen_pixel_bounds_ = config ? config->pixel_bounds : DesktopRect();
	dip_to_pixel_scale_ = config ? config->dip_to_pixel_scale : 1.0f;
	} else {
	screen_pixel_bounds_ = desktop_config_.pixel_bounds;
	dip_to_pixel_scale_ = desktop_config_.dip_to_pixel_scale;
	}

	// Release existing buffers, which will be of the wrong size.
	ReleaseBuffers();

	// Clear the dirty region, in case the display is down-sizing.
	helper_.ClearInvalidRegion();

	// Re-mark the entire desktop as dirty.
	helper_.InvalidateScreen(screen_pixel_bounds_.size());

	// Make sure the frame buffers will be reallocated.
	queue_.Reset();
	}

	bool ScreenCapturerMac::RegisterRefreshAndMoveHandlers() {
	RTC_DCHECK(thread_checker_.IsCurrent());
	desktop_config_ = desktop_config_monitor_->desktop_configuration();
	for (const auto& config : desktop_config_.displays) {
	size_t pixel_width = config.pixel_bounds.width();
	size_t pixel_height = config.pixel_bounds.height();
	if (pixel_width == 0 \|\| pixel_height == 0) continue;
	CGDirectDisplayID display_id = config.id;
	DesktopVector display_origin = config.pixel_bounds.top_left();

	CGDisplayStreamFrameAvailableHandler handler = ^(CGDisplayStreamFrameStatus status,
	uint64_t display_time,
	IOSurfaceRef frame_surface,
	CGDisplayStreamUpdateRef updateRef) {
	RTC_DCHECK(thread_checker_.IsCurrent());
	if (status == kCGDisplayStreamFrameStatusStopped) return;

	// Only pay attention to frame updates.
	if (status != kCGDisplayStreamFrameStatusFrameComplete) return;

	size_t count = 0;
	const CGRect* rects =
	CGDisplayStreamUpdateGetRects(updateRef, kCGDisplayStreamUpdateDirtyRects, &count);
	if (count != 0) {
	// According to CGDisplayStream.h, it's safe to call
	// CGDisplayStreamStop() from within the callback.
	ScreenRefresh(display_id, count, rects, display_origin, frame_surface);
	}
	};

	rtc::ScopedCFTypeRef<CFDictionaryRef> properties_dict(
	CFDictionaryCreate(kCFAllocatorDefault,
	(const void*[]){kCGDisplayStreamShowCursor},
	(const void*[]){kCFBooleanFalse},
	1,
	&kCFTypeDictionaryKeyCallBacks,
	&kCFTypeDictionaryValueCallBacks));

	CGDisplayStreamRef display_stream = CGDisplayStreamCreate(
	display_id, pixel_width, pixel_height, 'BGRA', properties_dict.get(), handler);

	if (display_stream) {
	CGError error = CGDisplayStreamStart(display_stream);
	if (error != kCGErrorSuccess) return false;

	CFRunLoopSourceRef source = CGDisplayStreamGetRunLoopSource(display_stream);
	CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopCommonModes);
	display_streams_.push_back(display_stream);
	}
	}

	return true;
	}

	void ScreenCapturerMac::UnregisterRefreshAndMoveHandlers() {
	RTC_DCHECK(thread_checker_.IsCurrent());

	for (CGDisplayStreamRef stream : display_streams_) {
	CFRunLoopSourceRef source = CGDisplayStreamGetRunLoopSource(stream);
	CFRunLoopRemoveSource(CFRunLoopGetCurrent(), source, kCFRunLoopCommonModes);
	CGDisplayStreamStop(stream);
	CFRelease(stream);
	}
	display_streams_.clear();

	// Release obsolete io surfaces.
	desktop_frame_provider_.Release();
	}

	void ScreenCapturerMac::ScreenRefresh(CGDirectDisplayID display_id,
	CGRectCount count,
	const CGRect* rect_array,
	DesktopVector display_origin,
	IOSurfaceRef io_surface) {
	if (screen_pixel_bounds_.is_empty()) ScreenConfigurationChanged();

	// The refresh rects are in display coordinates. We want to translate to
	// framebuffer coordinates. If a specific display is being captured, then no
	// change is necessary. If all displays are being captured, then we want to
	// translate by the origin of the display.
	DesktopVector translate_vector;
	if (!current_display_) translate_vector = display_origin;

	DesktopRegion region;
	for (CGRectCount i = 0; i < count; ++i) {
	// All rects are already in physical pixel coordinates.
	DesktopRect rect = DesktopRect::MakeXYWH(rect_array[i].origin.x,
	rect_array[i].origin.y,
	rect_array[i].size.width,
	rect_array[i].size.height);

	rect.Translate(translate_vector);

	region.AddRect(rect);
	}
	// Always having the latest iosurface before invalidating a region.
	// See https://bugs.chromium.org/p/webrtc/issues/detail?id=8652 for details.
	desktop_frame_provider_.InvalidateIOSurface(
	display_id, rtc::ScopedCFTypeRef<IOSurfaceRef>(io_surface, rtc::RetainPolicy::RETAIN));
	helper_.InvalidateRegion(region);
	}

	std::unique_ptr<DesktopFrame> ScreenCapturerMac::CreateFrame() {
	std::unique_ptr<DesktopFrame> frame(new BasicDesktopFrame(screen_pixel_bounds_.size()));
	frame->set_dpi(
	DesktopVector(kStandardDPI * dip_to_pixel_scale_, kStandardDPI * dip_to_pixel_scale_));
	return frame;
	}

	} // namespace webrtc