as3鱼眼放大镜

package {
//hi.baidu.com/inuko
//bitmapdata fisheye magnifier
//原创代码，如有雷同，纯属巧合
/*
本例是使用近似算法，只是最简单的鱼眼应用。此类绑定一个以0,0为中心，半径R=50的圆即可使用。也可以自行绘制放大镜子。
原理很简单，可以baidu下。
须和被放大的object封在一个mc里。这样bitmapdata.draw比较方便。涉及到层级问题，不这么做执行效率较低。
可以用模糊滤镜使之更平滑，不建议使用。
需要近远调节，可以自行写 放大镜与物件的距离，放大镜与人眼的距离 与 放大倍数的映射关系
this is a proximation. a simple fisheye.bind it with a sprite which has a circle which r=100 in point(0,0),u can draw your own magnifier.
just put it in a movie,and then it can render the parent
the theory is concentric circles filled with different scaled original pictures
可以用tweener做动画 move with tweener class
Tweener.addTween(myMovieClip, {x:10, time:1,onUpdate:magnifier.render});
时间轴动画可以用enterFrame   move in flash
function enterFrameH(e){
   if(currentFrame>arg&&currentFrame<arg){ //动画范围 moving frames range
    magnifier.render()
   }
}
*/
import flash.display.Sprite;
import flash.display.MovieClip;
import flash.display.BitmapData;
import flash.geom.Rectangle;
import flash.geom.Matrix;
import flash.geom.Point;
import flash.filters.BlurFilter
public class magnifier extends Sprite {
   public var scaleMax=2; //最大放缩
   public var scaleMin=1; //最小放缩
   public var scaleStep=32; //精细度，即同新圆数 render steps,as same as concentric circles number
 
   //预存储提高执行效率   defined these in init function to upgrad efficiency
   private var scaleArr=[];
   private var matrixArr=[];
   private var rArr=[];
   private var spriteArr=[]
 
   private var nowWidth;    //当前放大镜显示圆的直径，即bimmapdata绘制区域   the rendercircle's width
   public var bmpd=new BitmapData(10,10);
   public var bmpd_=new BitmapData(10,10);
   public var rect;
   public var point=new Point(0,0)
   //public var blur=new BlurFilter(3,3,1) 用模糊滤镜可以更平滑，但是太卡，不建议   make it smoother,but increase the scaleStep is better
   public function magnifier(scaleMax=2,scaleMin=1,scaleStep=32) {
    this.scaleMax=scaleMax;
    this.scaleMin=scaleMin;
    this.scaleStep=scaleStep;
    init();
    //addEventListener("enterFrame",render); //render in each frame,can wirte these outside the class
    render()
   }
   public function init() {
    var d=(scaleMax-scaleMin)/(scaleStep-1);
    if (d<0) {
     scaleMax=scaleMin
     d=0
     return;
    }
    nowWidth=this.scaleX*100;
    for (var i=0; i<=scaleStep; i++) {
     scaleArr[i]=scaleMin+i*d;//先缓冲提高效率,从大带小
     rArr[i]=50*(scaleStep-i+1)/(scaleStep+1);
     matrixArr[i]=new Matrix();
     matrixArr[i].scale(scaleArr[i],scaleArr[i]);
     matrixArr[i].translate(-50*scaleArr[i],-50*scaleArr[i])
     spriteArr[i]=new Sprite()
     //if(i>0){
      //spriteArr[i].filters=[blur] //用模糊滤镜可以更平滑，但是太卡，不建议   make it smoother,but increase the scaleStep is better
     //}
     addChild(spriteArr[i])
    }
   }
   public function render(e=null) {
    var i
    this.visible=false //不显示，以免绘制自身   invisible to avoid draw magnifier self
    rect=new Rectangle(this.x-nowWidth/2,this.y-nowWidth/2,nowWidth,nowWidth); //实际范围 true bitmapdata.draw area
    bmpd.dispose()
 
    bmpd=new BitmapData(this.parent.width,this.parent.height,true);
    bmpd.draw(this.parent,null,null,null,rect,true); 
 
    bmpd_.dispose()
    bmpd_=new BitmapData(nowWidth,nowWidth)
    bmpd_.copyPixels(bmpd,rect,point) //拷贝实际范围到新的bitmapdata，方便放缩的matrix计算 copy to a new bitmapdata,so can be easier to calc matrix
    for (i=0; i<=scaleStep; i++) {
     spriteArr[i].graphics.clear()
     //spriteArr[i].graphics.lineStyle(1,0) 圆外框，此行可以帮助理解原理 help to understand&debug
     spriteArr[i].graphics.beginBitmapFill(bmpd_,matrixArr[i],false,true); //填充不同matrix的圆   fill circles with difference matrix
     spriteArr[i].graphics.drawCircle(0,0,rArr[i]);
     spriteArr[i].graphics.endFill();
    }
    this.visible=true
   }
}
}