Scale a set of points in a zooming method, relative to an origin point.

Apply a set of points to an instance of Zoom, then apply an update().

const zoom = new Zoom(stage, pointList)

const origin = {x: 100, y: 100}
    , factor = 1.5 // 50% bigger.

// run `update` when a change occurs.
zoom.update(origin, factor)

// Draw points.
zoom.zoomPoints.pen.indicators(ctx, { color: 'gray', width: 1})