function DrawImage(ImgD,w,h){ 
   // alert("1236546");
     var image=new Image(); 
     //w,ͼƬµÄ¿í£¬h,ͼƬµÄ¸ß¡£
     image.src=ImgD.src; 
     if(image.width>0 && image.height>0){ 
      flag=true; 
      if(image.width/image.height>= w/h){ 
       if(image.width>w){
        ImgD.width=w; 
        ImgD.height=(image.height*w)/image.width; 
       }else{ 
        ImgD.width=image.width;
        ImgD.height=image.height; 
       } 
       ImgD.alt=image.width+"x"+image.height; 
      } 
      else{ 
       if(image.height>h){
        ImgD.height=h; 
        ImgD.width=(image.width*h)/image.height; 
       }else{ 
        ImgD.width=image.width;
        ImgD.height=image.height; 
       } 
       ImgD.alt=image.width+"x"+image.height; 
      } 
     }
    }
    
    function filechange(imgid,width,height,src){
    	
		var image=new Image(); 
		image=document.getElementById(imgid);
		image.width=width;
		image.height=height;
		image.src=src;
		
		DrawImage(image,width,height);
	}