layer.draggable.updatePosition(point)

Function to override the final value before setting it. Allows you to add your own behaviour to a draggable. This allows you to create draggable layers that snap between certain distances.
译：函数来设置前覆盖的最终值。允许您自己的行为添加到拖动。这允许您创建某些距离之间单元可拖动层。

Arguments（参数）

point — An object with x and y properties.
译：点 - 与x和y属性的对象。

layerA = new Layer
layerA.draggable.enabled = true

# Round numbers to a set amount 
round = (number, nearest) ->
    Math.round(number / nearest) * nearest

# Drag in increments of 20px 
layerA.draggable.updatePosition = (point) ->
    point.x = round(point.x, 20)
    point.y = round(point.y, 20)
    return point