AS3 Rotate an object around its center point

Question

I want this object to rotate around its center rather than the top left corner. The code looks like this:

        switch (event.keyCode)
        {
                   


        

Answer 1

The following will rotate around center :

public function rotateAroundCenter(object:DisplayObject, angleDegrees:Number):void {
    if (object.rotation == angleDegrees) {
        return;
    }

    var matrix:Matrix = object.transform.matrix;
    var rect:Rectangle = object.getBounds(object.parent);

    matrix.translate(-(rect.left + (rect.width / 2)), -(rect.top + (rect.height / 2)));
    matrix.rotate((angleDegrees / 180) * Math.PI);
    matrix.translate(rect.left + (rect.width / 2), rect.top + (rect.height / 2));
    object.transform.matrix = matrix;

    object.rotation = Math.round(object.rotation);
}

It translates the center of the object to 0,0 then rotate it and then translate it back.