JS控制图片显示的大小（图片等比例缩放）

http://www.cnblogs.com/xiaochaohuashengmi/archive/2010/06/01/1749571.html

<script type="text/javascript">
function AutoResizeImage(maxWidth,maxHeight,objImg){
var img = new Image();
img.src = objImg.src;
var hRatio;
var wRatio;
var Ratio = 1;
var w = img.width;
var h = img.height;
wRatio = maxWidth / w;
hRatio = maxHeight / h;
if (maxWidth ==0 && maxHeight==0){
Ratio = 1;
}else if (maxWidth==0){//
if (hRatio<1) Ratio = hRatio;
}else if (maxHeight==0){
if (wRatio<1) Ratio = wRatio;
}else if (wRatio<1 || hRatio<1){
Ratio = (wRatio<=hRatio?wRatio:hRatio);
}
if (Ratio<1){
w = w * Ratio;
h = h * Ratio;
}
objImg.height = h;
objImg.width = w;
}
</script>

<br />
原图显示（534 X 800）<br />
onload="AutoResizeImage(0,0,this)<br />
<a href="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" border="0" width="0" height="0" onload="AutoResizeImage(0,0,this)" alt="534 X 800"/></a><br/><br />

1.按宽度250压缩,不限制高度 按比例压缩<br />
onload="AutoResizeImage(250,0,this)"<br />
<a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" border="0" width="0" height="0" onload="AutoResizeImage(250,0,this)"  alt="250 X 374"/></a><br /><br />

2.按高度250压缩,不限制宽度 按比例压缩<br />
onload="AutoResizeImage(0,250,this)"<br />
<a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" border="0" width="0" height="0" onload="AutoResizeImage(0,250,this)"  alt="166 X 250"/></a><br /><br />

3.按高度250宽度250 按比例压缩<br />
onload="AutoResizeImage(250,250,this)"<br />
<a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" border="0" width="0" height="0" onload="AutoResizeImage(250,250,this)"  alt="200 X 300"/></a><br /><br />

4.高宽不等比例压缩 （400 X 512）,此时高度不变，会自动按高度的比例压缩。<br />
onload="AutoResizeImage(400,512,this)"<br />
<a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" border="0" width="0" height="0" onload="AutoResizeImage(400,512,this)"  alt="341 X 512"/></a><br /><br />

5.高宽不等比例压缩 （300 X 600）,此时宽度不变，会自动按宽度的比例压缩。<br />
onload="AutoResizeImage(300,600,this)"<br />
<a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" border="0" width="0" height="0" onload="AutoResizeImage(300,600,this)"  alt="300 X 449"/></a><br /><br />

6.如果图片本来的高度和宽度小于压缩的最大高度和宽度，则不会拉大显示图片（按原图显示）<br />
原图444 x 207,压缩为 500 x 600,将保持原图显示<br />
onload="AutoResizeImage(500,600,this)"<br />
<a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><img src="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/242776/o_20070410_b7409cd284a0f799a357uePcEFa6ty0X.jpg" border="0" width="0" height="0" onload="AutoResizeImage(500,600,this)"  alt="444 X 207"/></a><br /><br />
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