让图片按比例缩放显示

<script language="JavaScript" type="text/javascript"> <!-- var flag=false; function DrawImage(ImgD) {    var image=new Image();    image.src=ImgD.src;    if(image.width>0 && image.height>0)    {       flag=true;       if(image.width/image.height>= 157/107)       {          if(image.width>157)          {             ImgD.width=157;             ImgD.height=(image.height*107)/image.width;          }          else          {             ImgD.width=image.width;             ImgD.height=image.height;          }          /*ImgD.alt="bigpic" */       }       else       {          if(image.height>107)          {             ImgD.height=107;             ImgD.width=(image.width*107)/image.height;           }          else          {             ImgD.width=image.width;             ImgD.height=image.height;           }     /*ImgD.alt="bigpic" */        }     } } //--> </script> <img src="图片" border=0 width="180" height="110" onload="DrawImage(this);"> width="180" height="110" 注意这里最好限定,如果不限定加载图时会成原大,然后再缩小,这个过程如果图大了很难看的.这里是宽度和高度,在前面的JS里改,这里也作相应的改.