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jquery圖片上傳時依指定比例預覽（附程式碼）

php中世界最好的语言原創: 2018-04-26 17:56:131867瀏覽

這次帶給大家jquery圖片上傳時按指定比例預覽（附代碼），jquery圖片上傳時按指定比例預覽的注意事項有哪些，下面就是實戰案例，一起來看一下。

//**********************图片上传预览插件************************* 
(function($) { 
jQuery.fn.extend({ 
uploadPreview: function(opts) { 
opts = jQuery.extend({ 
width: 0, 
height: 0, 
imgp: "#imgp", 
imgType: ["gif", "jpeg", "jpg", "bmp", "png"], 
callback: function() { return false; } 
}, opts || {}); 
var _self = this; 
var _this = $(this); 
var imgp = $(opts.imgp); 
imgp.width(opts.width); 
imgp.height(opts.height); 
autoScaling = function() { 
if ($.browser.version == "7.0" || $.browser.version == "8.0") imgp.get(0).filters.item("DXImageTransform.Microsoft.AlphaImageLoader").sizingMethod = "image"; 
var img_width = imgp.width(); 
var img_height = imgp.height(); 
if (img_width > 0 && img_height > 0) { 
var rate = (opts.width / img_width < opts.height / img_height) ? opts.width / img_width : opts.height / img_height; 
if (rate <= 1) { 
if ($.browser.version == "7.0" || $.browser.version == "8.0") imgp.get(0).filters.item("DXImageTransform.Microsoft.AlphaImageLoader").sizingMethod = "scale"; 
imgp.width(img_width * rate); 
imgp.height(img_height * rate); 
} else { 
imgp.width(img_width); 
imgp.height(img_height); 
} 
var left = (opts.width - imgp.width()) * 0.5; 
var top = (opts.height - imgp.height()) * 0.5; 
imgp.css({ "margin-left": left, "margin-top": top }); 
imgp.show(); 
} 
} 
_this.change(function() { 
if (this.value) { 
if (!RegExp("\.(" + opts.imgType.join("|") + ")$", "i").test(this.value.toLowerCase())) { 
alert("图片类型必须是" + opts.imgType.join("，") + "中的一种"); 
this.value = ""; 
return false; 
} 
imgp.hide(); 
if ($.browser.msie) { 
if ($.browser.version == "6.0") { 
var img = $("<img />"); 
imgp.replaceWith(img); 
imgp = img; 
var image = new Image(); 
image.src = &#39;file:///&#39; + this.value; 
imgp.attr(&#39;src&#39;, image.src); 
autoScaling(); 
} 
else { 
imgp.css({ filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image)" }); 
imgp.get(0).filters.item("DXImageTransform.Microsoft.AlphaImageLoader").sizingMethod = "image"; 
try { 
imgp.get(0).filters.item(&#39;DXImageTransform.Microsoft.AlphaImageLoader&#39;).src = this.value; 
} catch (e) { 
alert("无效的图片文件！"); 
return; 
} 
setTimeout("autoScaling()", 100); 
} 
} 
else { 
var img = $("<img />"); 
imgp.replaceWith(img); 
imgp = img; 
imgp.attr(&#39;src&#39;, this.files.item(0).getAsDataURL()); 
imgp.css({ "vertical-align": "middle" }); 
setTimeout("autoScaling()", 100); 
} 
} 
}); 
} 
}); 
})(jQuery);

頁面部分:

<!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 runat="server"> 
<title></title> 
<meta content="" name="Keywords" /> 
<meta content="" name="Description" /> 
<meta content="text/html;charset=utf-8" http-equiv="Content-Type" /> 
<script type="text/
javascript
" src="js/jquery.pack.js"></script> 
<script type="text/javascript" src="js/uploadPreview/jquery.uploadPreview.js"></script> 
<script type="text/javascript"> 
$(document).ready(function() { 
//建议在#imgp的父元素上加个overflow:hidden;的css样式 
$("input").uploadPreview({ width: 200, height: 200, imgp: "#imgp", imgType: ["bmp", "gif", "png", "jpg"] }); 
}); 
</script> 
</head> 
<body> 
<form id="form1" runat="server"> 
<input type="file" /> 
<br /> 
<p style="width: 200px; height: 200px; overflow: hidden; border: 1px solid red;"> 
<p id="imgp"> 
</p> 
</p> 
</form> 
</body> 
</html>

相信看了本文案例你已經掌握了方法，更多精彩請關注php中文網其它相關文章！