javascript缩放图片
//javascript成比例缩放图片
<script language="JavaScript">
<!--
var flag=false;
function DrawImage(ImgD){
var image=new Image();
image.src=ImgD.src;
if(image.width>0 &amp;&amp; image.height>0){
flag=true;
if(image.width/image.height>= 140/125){
if(image.width>140){
ImgD.width=140;
ImgD.height=(image.height*140)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
else{
if(image.height>125){
ImgD.height=125;
ImgD.width=(image.width*125)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
}
}
//-->
</script>
图片引用：
<a target="_blank" href="images/<%=rsmallimg%>">
<img src="images/<%=rsmallimg%>" onload="javascript:DrawImage(this);" alt="<%=rname%>" width="140" height="125" border="0" style="border: 1px solid #000000"></a><BR>
//功能: 鼠标滚轮自由缩放, 图片大小自定义按比例缩小, 图片大小可在装入时初始化...
<script language="javascript" type="text/javascript">
function resizeimg(ImgD,iwidth,iheight) {
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0){
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;
}
ImgD.style.cursor= "pointer"; //改变鼠标指针
ImgD.onclick = function() { window.open(this.src);} //点击打开大图片
if (navigator.userAgent.toLowerCase().indexOf("ie") > -1) { //判断浏览器，如果是IE
ImgD.title = "请使用鼠标滚轮缩放图片，点击图片可在新窗口打开";
ImgD.onmousewheel = function img_zoom() //滚轮缩放
{
var zoom = parseInt(this.style.zoom, 10) || 100;
zoom += event.wheelDelta / 12;
if (zoom> 0) this.style.zoom = zoom + "%";
return false;
}
} else { //如果不是IE
ImgD.title = "点击图片可在新窗口打开";
}
}
}
</script>
在需要实现等比缩放的图片上加上onload语句，图片装载时初始化大小。
具体实现代码如下:
<img name="" src="DSCN2152.JPG" onload="javascript:resizeimg(this,100,200)">
