Flash/Flex学习笔记(26)：不用startDrag和stopDrag的对象拖动
对于从Sprite类继承来的对象，要实现拖放当然是Flash/Flex学习笔记(13)：对象拖动(startDrag/stopDrag) 里讲的方法最方便，但是对于不是从Sprite类继承得来的对象，这startDrag/stopDrag是不能用的，这时候只能采用最通常用做法：利用Mouse_Down,Mouse_UP,Mouse_Move事件来处理注意：对象的Mouse_Move事件，只有当鼠标在对象上时才能被监听，如果用户鼠标移动过快，超出了对象的范围，该事件就不起作用了，所以监听Mouse_Move事件时，应该监听stage对象的Mouse_Move事件，而非对象本身的（详情见下面的代码）
package {
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.ui.MouseCursor;
import flash.ui.Mouse;
public class MouseMoveDrag extends Sprite {
private var offsetX:Number;
private var offsetY:Number;
private var arrBalls:Array;
private var _draggedBall:Ball;
public function MouseMoveDrag():void {
arrBalls=new Array(7);
for (var i:uint=0; i<arrBalls.length; i++) {
arrBalls=new Ball(20+Math.random()*30,Math.random()*0xffffff);
arrBalls.x=stage.stageWidth*Math.random();
arrBalls.y=stage.stageHeight*Math.random();
arrBalls.addEventListener(MouseEvent.MOUSE_DOWN, MouseDownHandler);
arrBalls.addEventListener(MouseEvent.MOUSE_UP, MouseUpHandler);
arrBalls.addEventListener(MouseEvent.MOUSE_OVER,MouseOverHandler);
arrBalls.addEventListener(MouseEvent.MOUSE_OUT,MouseOutHandler);
addChild(arrBalls);
}
}
function MouseOverHandler(e:MouseEvent):void {
Mouse.cursor=MouseCursor.BUTTON;
}
function MouseOutHandler(e:MouseEvent):void {
Mouse.cursor=MouseCursor.AUTO;
}
//开始移动
function MouseDownHandler(e:MouseEvent):void {
offsetX=e.localX;
offsetY=e.localY;
_draggedBall = e.target as Ball;
stage.addEventListener(MouseEvent.MOUSE_MOVE, stageMouseMoveHandler);
}
//停止拖动
function MouseUpHandler(e:MouseEvent):void {
_draggedBall = null;
//拖动完成后，移除舞台的Mouse_Move监听
stage.removeEventListener(MouseEvent.MOUSE_MOVE, stageMouseMoveHandler);
}
function stageMouseMoveHandler(e:MouseEvent):void {
//trace(e.target);
var _ball:Ball=e.target as Ball;
if (_ball!=null) {
//设置新的坐标
_ball.x=mouseX-offsetX;
_ball.y=mouseY-offsetY;
} else {
//trace("您拖得太快了!" + _draggedBall.toString());
if (_draggedBall!=null){
_draggedBall.x=mouseX-offsetX;
_draggedBall.y=mouseY-offsetY;
}
}
}
}
}
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