图片自适应

<img src="1.jpg" onload="GetF.call(this,20,100)"/>

<script language="JavaScript">

function GetF(maxW,maxH){
    var img = new Image();
    img.src = this.src;
    var maxWidth = maxW;
    var maxHeight= maxH;

    alert(img.width + "\n" + img.height);

    bi = img.width / img.height;
    bili = maxWidth / maxHeight;

    alert(bi + ‘ ‘ + bili);

    if(bili >= bi )
    {

        if( img.height > maxHeight )
        {
            this.height = maxHeight
        }
    }else
    {
        if( img.width > maxWidth )
        {
            this.width = maxWidth;
        }
    }
}
</script>