Use kCGDisplayStreamUpdateDirtyRects.

webrtc/modules/desktop_capture/screen_capturer_mac.mm

 /*
  *  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.
  */
 
@@ skipping 269 matching lines @@
   bool CgBlitPostLion(const DesktopFrame& frame,
                       const DesktopRegion& region);
 
   // Called when the screen configuration is changed.
   void ScreenConfigurationChanged();
 
   bool RegisterRefreshAndMoveHandlers();
   void UnregisterRefreshAndMoveHandlers();
 
   void ScreenRefresh(CGRectCount count, const CGRect *rect_array);
-  void ScreenUpdateMove(CGFloat delta_x,
-                        CGFloat delta_y,
-                        size_t count,
-                        const CGRect* rect_array);
   void ScreenRefreshCallback(CGRectCount count, const CGRect* rect_array);
   void ReleaseBuffers();
 
   std::unique_ptr<DesktopFrame> CreateFrame();
 
   Callback* callback_ = nullptr;
 
   CGLContextObj cgl_context_ = nullptr;
   ScopedPixelBufferObject pixel_buffer_object_;
 
@@ skipping 634 matching lines @@
           if (display_stream_manager_->ShouldIgnoreUpdates())
             return;
 
           // Only pay attention to frame updates.
           if (status != kCGDisplayStreamFrameStatusFrameComplete)
             return;
 
           size_t count = 0;
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunguarded-availability"
-// TODO(erikchen): Use kCGDisplayStreamUpdateDirtyRects.
-          const CGRect* rects = CGDisplayStreamUpdateGetRects(
-              updateRef, kCGDisplayStreamUpdateMovedRects, &count);
-#pragma clang diagnostic pop
-          if (count != 0) {
-            CGFloat dx = 0;
-            CGFloat dy = 0;
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wunguarded-availability"
-            CGDisplayStreamUpdateGetMovedRectsDelta(updateRef, &dx, &dy);
-#pragma clang diagnostic pop
-            ScreenUpdateMove(dx, dy, count, rects);
-          }
-
-          count = 0;
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wunguarded-availability"
           rects = CGDisplayStreamUpdateGetRects(

[erikchen, 2016/10/10 21:54:42]

It's not clear to me whether CGDisplayStreamUpdateGetRects is still necessary,
and how it functions on refresh rects. Do we have a way of testing this?

[Sergey Ulanov, 2016/10/11 17:59:22]

Dirty rects are passed to helper_ and then Capture() gets dirty region from
helper_ and captures it for the new frame. Test coverage is lacking there :-(.
There are some unittests in screen_capturer_mac_unittest.cc, but they perform
only very minimal checks. There are also tests in screen_capturer_unittest.cc,
but they are disabled on Mac because there is currently no ScreenDrawer
implementation for Mac.

To test this change you can build chrome with this CL and then load this app:
//chrome/common/extensions/docs/examples/api/desktopCapture
It should show correct screen updates when something changes on the screen.

-              updateRef, kCGDisplayStreamUpdateRefreshedRects, &count);
+              updateRef, kCGDisplayStreamUpdateDirtyRects, &count);
 #pragma clang diagnostic pop
           if (count != 0) {
             // According to CGDisplayStream.h, it's safe to call
             // CGDisplayStreamStop() from within the callback.
             ScreenRefreshCallback(count, rects);
           }
         };
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunguarded-availability"
     CGDisplayStreamRef display_stream = CGDisplayStreamCreate(
@@ skipping 27 matching lines @@
     // Convert from Density-Independent Pixel to physical pixel coordinates.
     DesktopRect rect = ScaleAndRoundCGRect(rect_array[i], dip_to_pixel_scale_);
     // Translate from local desktop to capturer framebuffer coordinates.
     rect.Translate(translate_vector);
     region.AddRect(rect);
   }
 
   helper_.InvalidateRegion(region);
 }
 
-void ScreenCapturerMac::ScreenUpdateMove(CGFloat delta_x,
-                                         CGFloat delta_y,
-                                         size_t count,
-                                         const CGRect* rect_array) {
-  // Translate |rect_array| to identify the move's destination.
-  CGRect refresh_rects[count];
-  for (CGRectCount i = 0; i < count; ++i) {
-    refresh_rects[i] = CGRectOffset(rect_array[i], delta_x, delta_y);
-  }
-
-  // Currently we just treat move events the same as refreshes.
-  ScreenRefresh(count, refresh_rects);
-}
-
 void ScreenCapturerMac::ScreenRefreshCallback(CGRectCount count,
                                               const CGRect* rect_array) {
   if (screen_pixel_bounds_.is_empty())
     ScreenConfigurationChanged();
   ScreenRefresh(count, rect_array);
 }
 
 std::unique_ptr<DesktopFrame> ScreenCapturerMac::CreateFrame() {
   std::unique_ptr<DesktopFrame> frame(
       new BasicDesktopFrame(screen_pixel_bounds_.size()));
@@ skipping 16 matching lines @@
   }
 
   if (options.detect_updated_region()) {
     capturer.reset(new ScreenCapturerDifferWrapper(std::move(capturer)));
   }
 
   return capturer.release();
 }
 
 }  // namespace webrtc