Use kCGDisplayStreamUpdateDirtyRects.

webrtc/modules/desktop_capture/screen_capturer_mac.mm

Index: webrtc/modules/desktop_capture/screen_capturer_mac.mm
diff --git a/webrtc/modules/desktop_capture/screen_capturer_mac.mm b/webrtc/modules/desktop_capture/screen_capturer_mac.mm
index 316aa3dbe6a04da78bad6a39ea21f7baa22638d8..61b77c6afd1ffff0b02e35c06f3a428557127ddf 100644
--- a/webrtc/modules/desktop_capture/screen_capturer_mac.mm
+++ b/webrtc/modules/desktop_capture/screen_capturer_mac.mm
@@ -287,10 +287,6 @@ class ScreenCapturerMac : public ScreenCapturer {
   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();
 
@@ -945,25 +941,8 @@ bool ScreenCapturerMac::RegisterRefreshAndMoveHandlers() {
           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
@@ -1011,20 +990,6 @@ void ScreenCapturerMac::ScreenRefresh(CGRectCount count,
   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())