JS method to control the display size of images [image scaling function]-JS Tutorial-php.cn

JS method to control the display size of images [image scaling function]

高洛峰

Release： 2017-02-20 16:30:34

Original

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This article mainly introduces the method of JS to control the display size of images, that is, to realize the image scaling function, and involves the techniques related to JS dynamic operation of page element attributes. Friends in need can refer to the examples of this article

Describes the JS method to control the display size of images. Share it with everyone for your reference, the details are as follows:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>最新javascript自动按比例显示图片，按比例压缩图片显示</title>
<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>
</head>
<body>
<br />
原图显示（534 X 800）<br />
onload="AutoResizeImage(0,0,this)<br />
<a href="http://files.php.cn/file_images/article/201702/2017218121607044.jpg" target="_blank"><img src="http://files.jb51.net/file_images/article/201702/2017218121607044.jpg" border="0" width="0"    style="max-width:90%" 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://www.php.cn/" target="_blank"><img src="http://files.php.cn/file_images/article/201702/2017218121607044.jpg" border="0" width="0"    style="max-width:90%" 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://www.php.cn/" target="_blank"><img src="http://files.php.cn/file_images/article/201702/2017218121607044.jpg" border="0" width="0"    style="max-width:90%" 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://www.php.cn/" target="_blank"><img src="http://files.php.cn/file_images/article/201702/2017218121607044.jpg" border="0" width="0"    style="max-width:90%" 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://www.php.cn/" target="_blank"><img src="http://files.php.cn/file_images/article/201702/2017218121607044.jpg" border="0" width="0"    style="max-width:90%" 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://www.php.cn/" target="_blank"><img src="http://files.php.cnt/file_images/article/201702/2017218121607044.jpg" border="0" width="0"    style="max-width:90%" 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://www.php.cn/" target="_blank"><img src="http://files.php.cn/file_images/article/201702/2017218122006996.jpg" border="0" width="0"    style="max-width:90%" onload="AutoResizeImage(500,600,this)" alt="444 X 207"/></a><br /><br />
</body>
</html>

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##The operation effect diagram is as follows:

JS method to control the display size of images [image scaling function]

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