Re: Scale a Component About a Defined Point

[OmPrakash Muppirala]

On Fri, Jul 11, 2014 at 6:44 AM, Tintin <1955.mille.mig...@googlemail.com>
wrote:

> Hello
>
> I'm sure this should be simple, but I can't see it. I want to scale a Spark
> Group (and its content within) about a specific point, not its centre.
> Currently to achieve what I want I have to set the Group.ScaleX and
> Group.ScaleY and then calculate the offset required to keep my centre point
> fixed and then apply these new Group.X and Group.Y values.
>
> Is there a way to set the origin point about which you want to scale
> please?
>
> Regards
>
> Chris
>
>

I use this code to rotate a displayobject around a point:

        private var rotationMatrix:Matrix;
        private function rotate(obj:DisplayObject, angle:Number,
aroundX:Number, aroundY:Number):void
        {
            rotationMatrix = new Matrix();
            rotationMatrix.translate(-aroundX,-aroundY);
            rotationMatrix.rotate(Math.PI*angle/180);
            rotationMatrix.translate(aroundX,aroundY);
            obj.transform.matrix = rotationMatrix;
        }

I haven't tried scaling with this method, but maybe you can just modify it
for scaling like this:

        private var scaleMatrix:Matrix;
        private function rotate(obj:DisplayObject, scaleX:Number,
scaleY:Number, aroundX:Number, aroundY:Number):void
        {
            scaleMatrix= new Matrix();
            scaleMatrix.translate(-aroundX,-aroundY);
            scaleMatrix.scale(scaleX, scaleY);
            scaleMatrix.translate(aroundX,aroundY);
            obj.transform.matrix = scaleMatrix;
        }

I might be completely off base with my math here, but please do try and see
if it works.

Thanks,
Om



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