Add SetVideoMode API to avsettings

chromecast/public/avsettings.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMECAST_PUBLIC_AVSETTINGS_H_
 #define CHROMECAST_PUBLIC_AVSETTINGS_H_
 
 #include <stdint.h>
 
 #include "output_restrictions.h"
@@ skipping 273 matching lines @@
 
   // Supported HDR output modes.
   enum HdrOutputType {
     HDR_OUTPUT_SDR,  // not HDR
     HDR_OUTPUT_HDR,  // HDR with static metadata
     HDR_OUTPUT_DOLBYVISION  // DolbyVision output
   };
 
   // Gets the current HDR output type.
   virtual HdrOutputType GetHdrOutputType() = 0;
+
+  // Sets the video mode according to the given parameters:

[gfhuang, 2016/10/03 20:33:59]

HDMI video mode

[almasrymina1, 2016/10/03 20:51:54]

Done.

+  //
+  // allow_4k: if false, the resolution set will not be a 4K resolution.
+  //
+  // optimize_for_fps: *Attempts* to pick a refresh rate optimal for the given
+  // content frame rate. The content frame rate is expressed as framerate
+  // * 100. I.e. 24hz -> 2400, 23.98hz -> 23.98, etc.  Values <= 0 are ignored.
+  //
+  // Returns false if it will not attempt to set the video mode. This could be
+  // due to:
+  // HDMI state is not connected.
+  // Resolution set is already the best resolution with the params provided.
+  //
+  // Returns true otherwise.
+  //
+  // When this API return true, A SCREEN_INFO_CHANGED event fires when the video
+  // mode setting completes. When this API returns false, no event is fired.

[halliwell, 2016/10/03 20:27:34]

Could we just tighten up/organise this whole comment a bit?
* Use |allow_4k| notation for arguments
* 23.98hz example is wrong, should say 2398
* Return value description is very disorganised, could be more succinct and keep
the whole description of true/false together.  e.g. something like this:

Returns:
- true if mode change is beginning.  Caller should wait for SCREEN_INFO_CHANGED
event for mode change to complete.
- false if no made change has begun.  This could be because HDMI is
disconnected, or the current resolution is already good for the given
parameters.

[almasrymina1, 2016/10/03 20:51:54]

Done. I couldn't think of a better name, so I just made it very clear in the
comment. Suggestions welcome though :)

+  //
+  // This API only applies to devices that output HDMI.

[gfhuang, 2016/10/03 20:33:59]

", otherwise, simply return false"  (or true?)

[almasrymina1, 2016/10/03 20:51:54]

Done.

+  virtual bool SetHdmiVideoMode(bool allow_4k, int optimize_for_fps) = 0;
 };
 
 }  // namespace chromecast
 
 #endif  // CHROMECAST_PUBLIC_AVSETTINGS_H_