function DrawImage(ImgD,width,height){ 
    var image=new Image(); 
    var iwidth = width; 
    var iheight = height; 
    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=image.width+"×"+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; 
            } 
          //  ImgD.alt=image.width+"×"+image.height; 
        } 
    } 
}
//<img src="图片" onload="javascript:DrawImage(this,100,100)">