ui/src/main/java/ucar/nc2/ui/image/SourcePicture.java
public void loadPicture( URL imageUrl, double rotation ) {
		if ( pictureStatusCode == LOADING ) {
			stopLoadingExcept( imageUrl );
		}
		this.imageUrl = imageUrl;
		this.rotation = rotation;
		loadPicture();

	}
public void loadPicture( URL imageUrl, double rotation ) {
		if ( pictureStatusCode == LOADING ) {
			stopLoadingExcept( imageUrl );
		}
		this.imageUrl = imageUrl;
		this.rotation = rotation;
		loadPicture();

	}
method to invoke with a filename or URL of a picture that is to be loaded in
the main thread.