Is there an event for when a MovieClip changes position?

I'd like to be notified when a MovieClip changes position, regardless of whether the position was changed by m开发者_运维技巧y code, or by the built-in drag operations. Is there such an event?

There's none built in. You have basically 2 main options:

1) Either poll repeatedly to check if the position has changed. 2) Create a new class that extends MovieClip and override the set x and y properties to fire an event:

public class PosNotifyMC extends MovieClip
{

    // the name of the event we're firing
    public static const MOVED:String = "moved";

    // override the set x property
    override public function set x( n:Number ):void
    {
        super.x = n;
        this.dispatchEvent( new Event( PosNotifyMC.MOVED ) );
    }

    // override the set y property
    override public function set x( n:Number ):void
    {
        super.x = n;
        this.dispatchEvent( new Event( PosNotifyMC.MOVED ) );
    }

}

If your position is changing a lot, then keep a local event and repeatedly fire that instead of creating a new one every time. You can also create a new Event class that holds the updated position if you wanted as well.

+1 @divillysausages :)

then you can do something dirty and monitor "manually" the changes.

the MovieClip class is dynamic so we can create variables to store the last X/Y position then perform a delta on EnterFrame. if the delta is not 0 then the clip has moved.

that's really ugly:

package  
{
import flash.display.MovieClip;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;

public class Mover extends Sprite 
{
    private var mc:MovieClip;
    public function Mover() 
    {

        mc = new MovieClip();
        mc.graphics.beginFill( 0xCC00FF );
        mc.graphics.drawRect( 0, 0, 50, 50 );
        addChild( mc );

        //storing dynamic properties
        mc.lx = mc.x;
        mc.ly = mc.y;

        //and add monitoring function
        mc.addEventListener( Event.ENTER_FRAME, onEnterFrameHandler );

        mc.addEventListener( MouseEvent.MOUSE_DOWN, mouseHandler );
        mc.addEventListener( MouseEvent.MOUSE_UP, mouseHandler );

        //move clip from outisde
    //  this.addEventListener( Event.ENTER_FRAME, moveClipHandler );
    }

    private function moveClipHandler(e:Event):void 
    {
        mc.x++
    }

    private function mouseHandler(e:MouseEvent):void 
    {
        switch( e.type )
        {
            case MouseEvent.MOUSE_DOWN:         ( e.target as MovieClip ).startDrag();              break;
            case MouseEvent.MOUSE_UP:           ( e.target as MovieClip ).stopDrag();               break;
        }
    }

    private function onEnterFrameHandler(e:Event):void 
    {
        var m:MovieClip = e.target as MovieClip;
        //check the delta
        if ( m.x != m.lx || m.y != m.ly ) trace( 'moved!' );
        m.lx = m.x;
        m.ly = m.y;
    }

}

}

but it works :)

it would be a good idea to centralize the delta checks in a class that would give the abilty to register / unregister clips and DisplayObjects as needed.