Move direct use of VideoCapturer::VideoAdapter to VideoSinkWants.

webrtc/media/base/videobroadcaster.cc

Index: webrtc/media/base/videobroadcaster.cc
diff --git a/webrtc/media/base/videobroadcaster.cc b/webrtc/media/base/videobroadcaster.cc
index e369ee07c632480404080415271572d593c87f06..0ace19434e6d7af31d655fd1b02027305ee1df96 100644
--- a/webrtc/media/base/videobroadcaster.cc
+++ b/webrtc/media/base/videobroadcaster.cc
@@ -10,6 +10,8 @@
 
 #include "webrtc/media/base/videobroadcaster.h"
 
+#include <limits>
+
 #include "webrtc/base/checks.h"
 
 namespace rtc {
@@ -30,12 +32,7 @@ void VideoBroadcaster::AddOrUpdateSink(
   } else {
     sink_pair->wants = wants;
   }
-
-  // Rotation must be applied by the source if one sink wants it.
-  current_wants_.rotation_applied = false;
-  for (auto& sink_pair : sinks_) {
-    current_wants_.rotation_applied |= sink_pair.wants.rotation_applied;
-  }
+  UpdateWants();
 }
 
 void VideoBroadcaster::RemoveSink(
@@ -49,6 +46,7 @@ void VideoBroadcaster::RemoveSink(
                                 return sink_pair.sink == sink;
                               }),
                sinks_.end());
+  UpdateWants();
 }
 
 bool VideoBroadcaster::frame_wanted() const {
@@ -79,4 +77,35 @@ VideoBroadcaster::SinkPair* VideoBroadcaster::FindSinkPair(
   return nullptr;
 }
 
+void VideoBroadcaster::UpdateWants() {
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  // Rotation must be applied by the source if one sink wants it.
+  current_wants_.rotation_applied = false;
+  int max_pixels = std::numeric_limits<int>::max();
+  int more_than_pixels = std::numeric_limits<int>::max();
+  for (auto& sink_pair : sinks_) {
+    current_wants_.rotation_applied |= sink_pair.wants.rotation_applied;
+    if (sink_pair.wants.max_pixel_count &&
+        max_pixels > *sink_pair.wants.max_pixel_count) {
+      max_pixels = *sink_pair.wants.max_pixel_count;
+    }
+
+    if (sink_pair.wants.max_pixel_count_step_up &&
+        more_than_pixels > *sink_pair.wants.max_pixel_count_step_up) {
+      more_than_pixels = *sink_pair.wants.max_pixel_count_step_up;
+    }
+  }
+
+  current_wants_.max_pixel_count_step_up =
+      (more_than_pixels < std::numeric_limits<int>::max() &&
+       max_pixels > more_than_pixels)
+          ? rtc::Optional<int>(more_than_pixels)
+          : rtc::Optional<int>();
+
+  current_wants_.max_pixel_count =
+      (max_pixels < std::numeric_limits<int>::max())
+          ? rtc::Optional<int>(max_pixels)
+          : rtc::Optional<int>();
+}
+

[pthatcher1, 2016/02/25 07:40:30]

I think this would be more readable:

VideoSinkWants wants;
for (auto& sink : sinks_) {
  // wants.rotation_applied == ANY(sink.wants.rotation_applied)
  if (sink.wants.rotation_applied) {
    wants.rotation_applied = true;
  }
  // wants.max_pixel_count == MIN(sink.wants.max_pixel_count)
  if (sink.wants.max_pixel_count && (!wants.max_pixel_count ||
(sink_wants.max_pixel_count < wants.max_pixel_count))) {
    wants.max_pixel_count = sink.wants.max_pixel_count;
  }
  // wants.max_pixel_count_step_up == MIN(sink.wants.max_pixel_count_step_up)
  if (sink.wants.max_pixel_count_step_up && (!wants.max_pixel_count_step_up ||
(sink_wants.max_pixel_count_step_up < wants.max_pixel_count_step_up))) {
    wants.max_pixel_count_step_up = sink.wants.max_pixel_count_step_up;
  }
}

current_wants_ = wants;

[nisse-webrtc, 2016/02/25 09:31:07]

I think there's one more thing done in Per's version (which maybe needs a
comment). If it turns out that MIN(max_pixel_step_up) >= MIN(max_pixel), then in
the merged wants, max_pixel_step_up is left unset.

The comparisons could also written as

  if (sink.wants.max_pixel_count.value_or(std::numeric_limits<int>::max()) 
     < max_pixels) {     
    max_pixels = *sink.wants.max_pixel_count;
  }

Which would be elegant if it weren't for the numeric_limits thing being so
lengthy. And as you can guess, I still find the rtc::Optional unnecessary, but I
won't insist if you really like that interface.

[perkj_webrtc, 2016/02/25 13:57:07]

Added that condition afterwards and went with pthatchers suggestion.

 }  // namespace rtc