[AS3/AS2 only] Normally, all transformations (scale, rotation, and position) are based on the DisplayObject's registration point (most often its upper left corner), but TransformAroundPoint allows you to define ANY point around which 2D transformations will occur during the tween. For example, you may have a dynamically-loaded image that you want to scale from its center or rotate around a particular point on the stage.
If you define an x or y value in the transformAroundPoint object, it will correspond to the custom registration point which makes it easy to position (as opposed to having to figure out where the original registration point should tween to). If you prefer to define the x/y in relation to the original registration point, do so outside the transformAroundPoint object, like:
TweenLite.to(mc, 3, {x:50, y:40, transformAroundPoint:{point:new Point(200, 300), scale:0.5, rotation:30}});
To define the point according to the target's local coordinates (as though it is inside the target), simply pass pointIsLocal:true in the transformAroundPoint object, like:
TweenLite.to(mc, 3, {transformAroundPoint:{point:new Point(200, 300), pointIsLocal:true, scale:0.5, rotation:30}});
Usage
import com.greensock.TweenLite;
import com.greensock.plugins.TweenPlugin;
import com.greensock.plugins.TransformAroundPointPlugin;
TweenPlugin.activate([TransformAroundPointPlugin]); //activation is permanent in the SWF, so this line only needs to be run once.
TweenLite.to(mc, 1, {transformAroundPoint:{point:new Point(100, 300), scaleX:2, scaleY:1.5, rotation:150}});
