JS控制图片显示的大小（图片等比例缩放）

摘自：http://www.qianyunlai.com/blog/397.html 

 

 

代码

DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<</SPAN>html xmlns="http://www.w3.org/1999/xhtml">
<</SPAN>head>
<</SPAN>meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<</SPAN>title>最新javascript自动按比例显示图片，按比例压缩图片显示</</SPAN>title>
<</SPAN>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<</SPAN>1) Ratio = hRatio;
}else if (maxHeight==0){
if (wRatio<</SPAN>1) Ratio = wRatio;
}else if (wRatio<</SPAN>1 || hRatio<</SPAN>1){
Ratio = (wRatio<=hRatio?wRatio:hRatio);
}
if (Ratio<</SPAN>1){
w = w * Ratio;
h = h * Ratio;
}
objImg.height = h;
objImg.width = w;
}
</</SPAN>script>
</</SPAN>head>
<</SPAN>body>
<</SPAN>br />
原图显示（534 X 800）<</SPAN>br />
onload="AutoResizeImage(0,0,this)<</SPAN>br />
<</SPAN>a href="http://p.blog.csdn.net/images/p_blog_csdn_net/feng_sundy/421506/o_09925c7bcead8c60f683298dacf497a6.jpg" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br/><</SPAN>br />
1.按宽度250压缩,不限制高度 按比例压缩<</SPAN>br />
onload="AutoResizeImage(250,0,this)"<</SPAN>br />
<</SPAN>a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br /><</SPAN>br />
2.按高度250压缩,不限制宽度 按比例压缩<</SPAN>br />
onload="AutoResizeImage(0,250,this)"<</SPAN>br />
<</SPAN>a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br /><</SPAN>br />
3.按高度250宽度250 按比例压缩<</SPAN>br />
onload="AutoResizeImage(250,250,this)"<</SPAN>br />
<</SPAN>a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br /><</SPAN>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。<</SPAN>br />
onload="AutoResizeImage(400,512,this)"<</SPAN>br />
<</SPAN>a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br /><</SPAN>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。<</SPAN>br />
onload="AutoResizeImage(300,600,this)"<</SPAN>br />
<</SPAN>a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br /><</SPAN>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）<</SPAN>br />
原图444 x 207,压缩为 500 x 600,将保持原图显示<</SPAN>br />
onload="AutoResizeImage(500,600,this)"<</SPAN>br />
<</SPAN>a href="http://blog.csdn.net/feng_sundy/archive/2008/06/19/2566028.aspx" target="_blank"><</SPAN>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"/></</SPAN>a><</SPAN>br /><</SPAN>br />
</</SPAN>body>
</</SPAN>html>

 

效果图：