API Subject to change soon.
returns the internal reference to the zoomer
creates a new d3.zoom layer
Subscribes a callback to the zoom event
Removes callback subscription
Returns the zoomer scale values
A helper method to limit the visual size of an object. Cap on how small an object can become and also how large it can be.
Pans and zooms the zoom layer over a given (transition
) time. If transition = 0 the pan and zoom is instant, else it is a time in milliseconds.