as3 判断鼠标移动方向

import flash.events.MouseEvent;
var odx:Number=mouseX;
var ody:Number=mouseY;
stage.addEventListener(MouseEvent.MOUSE_DOWN,onMouseDown_func)
stage.addEventListener(MouseEvent.MOUSE_UP, onMouseUp_func);

function onMouseDown_func(_evt:MouseEvent):void{
    stage.addEventListener(MouseEvent.MOUSE_MOVE, onMove);
}

function onMouseUp_func(_evt:MouseEvent):void{
    stage.removeEventListener(MouseEvent.MOUSE_MOVE, onMove);
}

function onMove(e:MouseEvent):void{
    var newx:Number=mouseX;
    var newy:Number=mouseY;
    if(newx>odx)trace("鼠标在右移")else trace("鼠标在左移")
    if(newy>ody)trace("鼠标在下移")else trace("鼠标在上移")

    odx=newx;
    ody=newy;
}