Exports a group of drawing elements as an image.
The group will be positioned at
[0, 0] in the exported image. Its dimensions will be used as the default dimensions for the image.
Scene images have to be of same origin or CORS-enabled.
The export operation is asynchronous and returns a promise. The promise will be resolved with a PNG image encoded as a Data URI.
The root group containing all elements to export.
The export options.
Promise<string> A promise that will be resolved with a PNG image encoded as a Data URI.