How to set the scale mode to stretch to full screen when using the VideoFragment to play a video on Leanback

Google's Leanback showcase video player without ExoPlayer

Google's Leanback showcase video player with ExoPlayer

I've tried out the leanback showcase from google and it too plays the videos on "fit to screen" mode with black bars on the sides. I can't find an option to change the scale mode anywhere on the API docs either

I had to look into the VideoFragment source to figure this one out. VideoFragment has a simple SurfaceView as the root element of its layout and all you have to do is make the SurfaceView match the parent (which is the device screen) width and height. To do that just override onVideoSizeChanged and use getSurfaceView to get a reference to the package-private SurfaceView instance used in the VideoFragment.

@Override
protected void onVideoSizeChanged(int width, int height) {
    switch (scaleMode) {
        // `scaleMode` flag indicates that this video should stretch to screen
        case MediaMetaData.SCALE_MODE_STRETCH:  
            View rootView = getView();
            SurfaceView surfaceView = getSurfaceView();
            ViewGroup.LayoutParams params = surfaceView.getLayoutParams();
            params.height = rootView.getHeight();
            params.width = rootView.getWidth();
            surfaceView.setLayoutParams(params);
            break;
        // When the video shouldn't stretch, just invoke super to have the VideoFragment's default behavior which is fit to screen
        default:                            
            super.onVideoSizeChanged(width, height);
    }
}