Why does the chromecast client declare its height and width as 720p to the receiver app?

Question

Why does the chromecast declare its client height and width to be 720p to the receiver app server?

I am trying to display non-video content and assumed I would be able to use the full 1080p resolution. The device reports to the TV that it is in 1080p 60hz but if you look at the on device developer tools it is only displaying my receiver app as 1280x720.

Is there a way to force the page to render at full resolution?

Answer 1

Chromecast devices have a different Graphics Window size than it's Video window - The Graphics window uses a 1280x720 resolution surface. The window.height and window.width properties are going to report 720 and 1280 respectively. However, Chromecast is capable of displaying video at up to 1080p resolution i.e. 1920x1080. Therefore applications should not use the screen size to select video content resolution.