ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Display programming
The following code (adapted from the previous example) allows two display objects, a circle and a square, to be moved
with the mouse. Whenever the mouse button is pressed over either one, that item is moved to the top of the Stage’s
display list, so that the dragged item always appears on top. (Code that is new or changed from the previous listing
appears in boldface.)
// This code creates a drag-and-drop interaction using the mouse-following
// technique.
// circle and square are DisplayObjects (e.g. MovieClip or Sprite
// instances).
import flash.display.DisplayObject;
import flash.events.MouseEvent;
var offsetX:Number;
var offsetY:Number;
var draggedObject:DisplayObject;
// This function is called when the mouse button is pressed.
function startDragging(event:MouseEvent):void
{
// remember which object is being dragged
draggedObject = DisplayObject(event.target);
}
// Record the difference (offset) between where the cursor was when
// the mouse button was pressed and the x, y coordinate of the
// dragged object when the mouse button was pressed.
offsetX = event.stageX - draggedObject.x;
offsetY = event.stageY - draggedObject.y;
// move the selected object to the top of the display list
stage.addChild(draggedObject);
// Tell Flash Player to start listening for the mouseMove event.
stage.addEventListener(MouseEvent.MOUSE_MOVE, dragObject);
// This function is called when the mouse button is released.
function stopDragging(event:MouseEvent):void
{
// Tell Flash Player to stop listening for the mouseMove event.
stage.removeEventListener(MouseEvent.MOUSE_MOVE, dragObject);
}
Last updated 6/6/2012
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