Register a callback to a specific state. The callback is executed once when the state is reached.
If webVis is already in that state the callback is triggered immediately.
A promise which throws an error if the requested state is invalid
The following states are allowed as target
init - Is reached when webVis is fully configured and set up. resourceStateUpdated - Is reached when there is state information available for all resources (This information can also be "still transcoding"). resourceProcessed - This is triggered when all resources are done transcoding. renderingFinished - This is triggered when webVis is done with rendering. So no more image changes are imminent.
Register a callback to a specific state. The callback is executed once when the state is reached. If webVis is already in that state the callback is triggered immediately.