If your plan is an image, this will zoom out one level. The level is equivalent to 50% of the dimensions of the container.
When zooming out, the plan attempts to zoom to the center of the current view, but if it can't, it zooms as far to the edge as it can and then takes more away from the opposite side.
Returns: Boolean (whether it has room to zoom out)
// assuming you already have access to `plan` as a Plan object // and that plan has an image plan.zoomOut();