Please help for Registration point to a movieclip/sprite

Question

I am new to AS3 and have a doubt on Registration point for
Movie clip / Sprite. Please help me the sample code for this
I simply draw a line using AS3 in flash environment. but i
used graphics.moveTo for center. but if i run this it is simply
taking x,y axis 0,0 and move around the stage. I want to move this
from center of the stage. please help.
below is my code
var line:Sprite = new Sprite()
addChild(line);
var cx:Number = stage.stageWidth/2;
var cy:Number = stage.stageHeight/2;
var radius:Number = 1;
var increase:Number = 0;
line.graphics.lineStyle(1, 0xff00ff);
line.addEventListener(Event.ENTER_FRAME, onEnter);
function onEnter(event:Event):void
increase += radius;
//trace(increase);
//line.graphics.moveTo(cx, cy);
line.graphics.lineTo(cx + increase, cy + increase);
line.rotation += 0.1;

Answer 1

to appear to control the registration point of line, make it
a child or an empty display object and offset it by -x,-y where x,y
is your choice for the apparent registration point. you can then
control the parent object and it will behave like your line with
changed registration point.