Background image configurator class.
The position to use. If null, defaults to BackgroundPosition.DEFAULT.
The repeat for the x and y axis. If null, this value defaults to BackgroundRepeat.REPEAT.
The repeat for the x axis. If null, this value defaults to BackgroundRepeat.REPEAT.
The repeat for the y axis. If null, this value defaults to BackgroundRepeat.REPEAT.
The size. If null, defaults to BackgroundSize.DEFAULT.
Return background image based on current configuration.