We set up the zoom behavior, meaning that our Canvas is
- listening on every mouse wheel and drag
- firing the zoomed() handler on each of these events
Let’s now fill our handler to do something to the globe.
What do we want to do? From a bird’s perspective, for each zoom, we want to establish the scale for the projection, apply it to the path, and redraw the globe a little bit bigger or a little smaller. For each drag, we would want to establish the new rotation values, apply them to the projection and path, and redraw the globe a little bit rotated. To get there, the handler should distinguish between a zoom and a drag. A zoom should lead to a projection-scale change and a drag should lead to a rotation change. ...
