以下是放在img标签的onload事件中的例如:<img src="icon/loading.gif" onload="DrawImage(this,120,100,true,'http://bbs.csdn.net/images/123.jpg')">
此方法在ie6、ie7、ie8中运行要报错:stack overflow at line:0 function DrawImage(ImgD,iwidth,iheight,IsCenter,url){    
//参数(图片,允许的宽度,允许的高度)    
var image=new Image();  
//image.src="";  /*先清空下缓存,ie中防止加载的不是最新的图片*/
image.src=typeof url=="undefined"||url==""||url==null?ImgD.src:url;    
 
ImgD.src  = image.src;  
if(image.width>0 && image.height>0){ 
if(image.width/image.height>= iwidth/iheight){    
if(image.width>iwidth){      
ImgD.width=iwidth;    
ImgD.height=(image.height*iwidth)/image.width;    
}else{    
ImgD.width=image.width;      
ImgD.height=image.height;    
}    
}else{     
if(image.height>iheight){      
ImgD.height=iheight;    
ImgD.width=(image.width*iheight)/image.height;            
}else{    
ImgD.width=image.width;      
ImgD.height=image.height;    
}   

if((IsCenter)){
ImgD.style.marginTop = ((iheight-ImgD.height)/2)+"px"; /*自动居中*/
}
}  
//ImgD.src  = image.src;