举例：

上面的flash展示源代码：

import index.base.geom.Dot;
import index.base.events.DotEvent;

var po1:Dot = new Dot(0,0,true);
var po2:Dot = new Dot(0,0,true);
po1.bind(p1,true);
po2.bind(p2,true);

po1.addEventListener(DotEvent.DOT_CHANGE,dotChangeFun);
po2.addEventListener(DotEvent.DOT_CHANGE,dotChangeFun);

function dotChangeFun(e:DotEvent):void{
  te.text = "物体1坐标：" + po1.x + "," + po1.y;
  te.appendText("\n物体2坐标：" + po2.x + "," + po2.y);
  te.appendText("\n两点之间距离：" + po1.from(po2));
  te.appendText("\n所形成的角度：" + po1.angle(po2));
  te.appendText("\n物体1所在象限：" + po1.quadrant(new Dot,false));
  te.appendText("\n物体2所在象限：" + po2.quadrant(new Dot,false));
  te.appendText("\n物体1对于物体2在象限：" + po2.quadrant(po1));
}

p1.addEventListener(MouseEvent.MOUSE_DOWN,p1MouseDownFun);
p2.addEventListener(MouseEvent.MOUSE_DOWN,p2MouseDownFun);

function p1MouseDownFun(e:MouseEvent):void{
  p1.startDrag();
  stage.addEventListener(MouseEvent.MOUSE_UP,p1MouseUpFun);
}

function p1MouseUpFun(e:MouseEvent):void{
  p1.stopDrag();
  stage.removeEventListener(MouseEvent.MOUSE_UP,p1MouseUpFun);
}

function p2MouseDownFun(e:MouseEvent):void{
  p2.startDrag();
  stage.addEventListener(MouseEvent.MOUSE_UP,p2MouseUpFun);
}

function p2MouseUpFun(e:MouseEvent):void{
  p2.stopDrag();
  stage.removeEventListener(MouseEvent.MOUSE_UP,p2MouseUpFun);
}

下面是类的源代码：

package index.base.geom{
 
  import flash.events.EventDispatcher;
  import flash.display.DisplayObject;
 
  import index.base.events.DotEvent;
 
  public class Dot extends EventDispatcher{
   
    private var _x:Number;
    private var _y:Number;
    private var dis:DisplayObject;
   
    public var isListen:Boolean;
   
    public function Dot(x_:Number = 0,y_:Number = 0,_isListen:Boolean = false){
      _x = x_;
      _y = y_;
      isListen = _isListen;
    }
   
    //绑定DisplayObject
    public function bind(_dis:DisplayObject,isInTime:Boolean = false):void{
      dis = _dis;
      updata();
      if(isInTime) dis.addEventListener("enterFrame",enterFrameFun);
    }
   
    //帧频繁事件
    private function enterFrameFun(e:Object):void{
      if(_x != dis.x) x = dis.x;
      if(_y != dis.y) y = dis.y;
    }
   
    //更新xy数据
    public function updata():void{
      if(dis != null){
        _x = dis.x;
        _y = dis.y;
      }
    }
   
    //计算该点与另外一点的距离
    public function from(_dot:Dot,isQuadrant:Boolean = false):Number{
      updata();
      var num:Number = Math.sqrt(Math.pow(_dot.x - _x,2) + Math.pow(_dot.y - _y,2));
      if(!isQuadrant) num = Math.abs(num);
      return num;
    }
   
    //计算该点与另外一点所形成的线段与水平线的夹角,按顺时间计算
    public function angle(_dot:Dot,isRadian:Boolean = false):Number{
      updata();
      var numx:Number = _dot.x - _x;
      var numy:Number = _dot.y - _y;
      var num:Number = Math.atan(numy/numx);
      if(!isRadian) num = num * 180 / Math.PI;
      return num;
    }
   
    //返回当前点处在另外一点的哪个象限中 或 返回另外一点处在当前点的哪个象限中
    public function quadrant(_dot:Dot,isMaster:Boolean = true):int{
      updata();
      if(_x == _dot.x || _y == _dot.y){
        return 0;
      }
     
      var num:int;
      var p1:Boolean = (_x - _dot.x) > 0;
      var p2:Boolean = (_y - _dot.y) > 0;
      num = isMaster ? (p1 ? (p2 ? 2 : 3) : (p2 ? 1 : 4)) : (p1 ? (p2 ? 4 : 1) : (p2 ? 3 : 2));
     
      return num;
    }
   
    //返回该点距0点的距离
    public function get length():Number{
      updata();
      var num:Number = Math.sqrt(Math.pow(_x,2) + Math.pow(_y,2));
      return num;
    }
   
    //清除显示对象
    public function clear():void{
      dis = null;
    }
   
    //改变X坐标
    public function set x(num:Number):void{
      _x = num;
      if(dis != null) dis.x = num;
      if(isListen) dispatchEvent(new DotEvent(DotEvent.DOT_CHANGE,true));
    }
   
    //设置X坐标
    public function get x():Number{
      updata();
      return _x;
    }
   
    //改变Y坐标
    public function set y(num:Number):void{
      _y = num;
      if(dis != null) dis.y = num;
      if(isListen) dispatchEvent(new DotEvent(DotEvent.DOT_CHANGE,true));
    }
   
    //设置Y坐标
    public function get y():Number{
      updata();
      return _y;
    }
  }
}

事件类的代码：

package index.base.events{
 
  import flash.events.Event;
 
  public class DotEvent extends Event{
   
    public static const DOT_CHANGE:String = "dotChange";
   
    public function DotEvent(type:String, bubbles:Boolean = false, cancelable:Boolean = false){
      super(type,bubbles,cancelable);
    }
  }
}

经典论坛交流：
http://bbs.blueidea.com/thread-2842487-1-1.html

本文链接：http://www.blueidea.com/tech/multimedia/2008/5706.asp　

出处：蓝色理想
责任编辑：bluehearts

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