requestThumbnail
abstract fun requestThumbnail(request: ThumbnailRequest, callback: ThumbnailCallback): Cancellable(source)
Asks for one frame.
Returns immediately and the frame arrives on callback. Cancelling the returned handle must stop the decode, not merely discard its result.
Return
a handle that cancels the request.
Parameters
request
Which frame, at what size.
callback
Receives the frame, or the failure, exactly once.