//图片按比例缩放 
var flag=false; 
function imgzoom(ImgD,TheWidht){ 
var image=new Image(); 
var iwidth = TheWidht;  //定义允许图片宽度 
var iheight = 1500;  //定义允许图片高度 
image.src=ImgD.src; 
if(image.width>0 && image.height>0){ 
flag=true; 
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; 
} 
ImgD.alt="点击放大图片，可使文字变清晰"; 
} 
else{ 
if(image.height>iheight){   
ImgD.height=iheight; 
ImgD.width=(image.width*iheight)/image.height;   
}else{ 
ImgD.width=image.width;   
ImgD.height=image.height; 
} 
ImgD.alt="点击放大图片，可使文字变清晰"; 
} 
} 
}  
//-->