//自动等比例变换缩放图片
function  DrawImage(ImgD,ImgW,ImgH){  
//调用示例：onload="javascript:DrawImage(this,160,120);"
	 var  flag=false;  
	 var  image=new  Image();  
	 image.src=ImgD.src;  
     if(image.width>0  &&  image.height>0){  
       flag=true;  
       if(image.width/image.height>=  ImgW/ImgH){  
         if(image.width>ImgW){      
         ImgD.width=ImgW;  
         ImgD.height=(image.height*ImgW)/image.width;  
         }else{  
         ImgD.width=image.width;      
         ImgD.height=image.height;  
         }  
         ImgD.alt=image.width+"×"+image.height;  
         }  
       else{  
         if(image.height>ImgH){      
         ImgD.height=ImgH;  
         ImgD.width=(image.width*ImgH)/image.height;            
         }else{  
         ImgD.width=image.width;      
         ImgD.height=image.height;  
         }  
         ImgD.alt=image.width+"×"+image.height;  
         }  
       }  
}    
//改变CSS样式
function Change_css_over(PicID)
{
 PicID.className="Pic_Alpha_over";
}
function Change_css_out(PicID)
{
 PicID.className="Pic_Alpha_out";
}

//加载图片
function preloadimg(url,obj){
var img=new Image();
//obj.innerHTML="<p>图片加载中...</p>";
img.onload=function(){obj.src = this.src;}
//img.onerror=function(){obj.innerHTML="图片加载失败！"};
img.src=url; //img.src一定要写在img.onload之后，否则在IE中会出现问题
}