remove drag and drop objects when exit frame on button click - actionscript-3

Question

i want to make flash application that allowed users to match picture with the box containing its first letter of the word. the method is drag and drop with target. i'm really new to this.
drag and drop target is working so far but my problem is when i exit the frame after moving the object, the drag and drop object still visible.
how can i remove this object when leaving frame?
here is what i got:
import flash.events.MouseEvent;
import flash.display.DisplayObject;
var objectoriginalX:Number;
var objectoriginalY:Number;
a.buttonMode = true;
a.addEventListener(MouseEvent.MOUSE_DOWN, pickupObject);
a.addEventListener(MouseEvent.MOUSE_UP, dropObject);
function pickupObject(event:MouseEvent):void
{
event.target.startDrag();
event.target.parent.addChild(event.target);
objectoriginalX = event.target.x;
objectoriginalY = event.target.y;
}
function dropObject(event:MouseEvent):void
{
event.target.stopDrag();
var matchingTargetName:String = "target" + event.target.name;
var matchingTarget:DisplayObject = getChildByName(matchingTargetName);
if(event.target.dropTarget != null && event.target.dropTarget.parent == matchingTarget)
{
event.target.removeEventListener(MouseEvent.MOUSE_DOWN, pickupObject);
event.target.removeEventListener(MouseEvent.MOUSE_UP, dropObject);
event.target.buttonMode = false;
event.target.x = matchingTarget.x;
event.target.y = matchingTarget.y;
}
else
{
event.target.x = objectoriginalX;
event.target.y = objectoriginalY;
}
}
thanks before, any suggestion will be appreciated
edited: this is the code i use to move to other scene
HOME1.addEventListener(MouseEvent.CLICK, fl_ClickToGoToScene_15);
function fl_ClickToGoToScene_15(event:MouseEvent):void
{
MovieClip(this.root).gotoAndStop(2, "Scene 1");
}

Answer 1

When through code you do something to a timeline object that causes the parentage to change, that timeline object will no longer be controlled by the timeline.
So when you do this:
event.target.parent.addChild(event.target);
(presumably to bring the item being dragged to the front), you are inadvertently telling Flash that this object is controlled by code now.
The solution, is to manually remove the object(s) by code when done with them. This can be done with removeChild(childObject).
Since you are likely dealing with multiple objects that can be dragged around, it would likely be easiest to just clear all children manually prior to going to the next frame:
removeChildren(); //remove all children of the current context (timeline)
nextFrame(); //go to the next frame, or play(); or whatever you want to do
If you are targeting an older version of flash (less than 11 doesn't support the removeChildren method), you can do this in it's place:
var i:int = numChildren;
while(i--){
removeChildAt(i);
}
Alternatively, if you don't desire to clear all children of the current timeline, you could just keep track of what's being dragged around and remove those object:
var draggedObjs:Array = [];
function pickupObject(event:MouseEvent):void
{
draggedObjs.push(event.target);
...rest of code
Then do this when ready to move on:
for each(obj in draggedObjs){
removeChild(obj);
}
draggedObjs = [];
nextFrame(); //or whatever
Another option, would be to duplicate the item clicked, add it to stage, then drag the duplicate and match the originals position to it on mouse move. When the drag is done, remove the duplicate from stage.