web前端|js教程
jQuery,本地预览,上传图片
web前端-js教程
本文实例介绍了基于JQUERY扩展，图片上传预览插件，目前兼容浏览器(IE 谷歌 火狐) 不支持safari，分享给大家供大家参考，具体内容如下
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HTML代码：
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图片上传预览演示原文
js代码：
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*参数说明: Img:图片ID;Width:预览宽度;Height:预览高度;ImgType:支持文件类型;Callback:选择文件显示图片后回调方法;*使用方法:
把需要进行预览的IMG标签外 套一个DIV 然后给上传控件ID给予uploadPreview事件$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120, ImgType: ["gif", "jpeg", "jpg", "bmp", "png"], Callback: function () { }});*/jQuery.fn.extend({uploadPreview: function (opts) {var _self = this,_this = $(this);opts = jQuery.extend({Img: "ImgPr",Width: 100,Height: 100,ImgType: ["gif", "jpeg", "jpg", "bmp", "png"],Callback: function () {}}, opts || {});_self.getObjectURL = function (file) {var url = null;if (window.createObjectURL != undefined) {url = window.createObjectURL(file)} else if (window.URL != undefined) {url = window.URL.createObjectURL(file)} else if (window.webkitURL != undefined) {url = window.webkitURL.createObjectURL(file)}return url};_this.change(function () {if (this.value) {if (!RegExp("\.(" + opts.ImgType.join("|") + ")$", "i").test(this.value.toLowerCase())) {alert("选择文件错误,图片类型必须是" + opts.ImgType.join("，") + "中的一种");this.value = "";return false}if ($.browser.msie) {try {$("#" + opts.Img).attr(src, _self.getObjectURL(this.files[0]))} catch (e) {var src = "";var obj = $("#" + opts.Img);var div = obj.parent("div")[0];_self.select();if (top != self) {window.parent.document.body.focus()} else {_self.blur()}src = document.selection.createRange().text;document.selection.empty();obj.hide();obj.parent("div").css({filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale),width: opts.Width + px,height: opts.Height + px});div.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = src}} else {$("#" + opts.Img).attr(src, _self.getObjectURL(this.files[0]))}opts.Callback()}})}});
直接上第二段代码，jquery js实现上传图片之前预览本地图片
#preview_wrapper{ display:inline-block; width:300px; height:300px; background-color:#CCC;} #preview_fake{ filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale); } #preview_size_fake{ filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);visibility:hidden; } #preview{ width:300px; height:300px; } function onUploadImgChange(sender){ if( !sender.value.match( /.jpg|.jpg|.jpg|.jpg/i ) ){alert(图片格式无效！);return false; } var objPreview = document.getElementByIdx_x(preview); var objPreviewFake = document.getElementByIdx_x(preview_fake); var objPreviewSizeFake = document.getElementByIdx_x(preview_size_fake); if( sender.files && sender.files[0] ){objPreview.style.display = lock;objPreview.style.width = auto;objPreview.style.height = auto; // Firefox 因安全性问题已无法直接通过 input[file].value 获取完整的文件路径objPreview.src = sender.files[0].getAsDataURL();}else if( objPreviewFake.filters ){// IE7,IE8 在设置本地图片地址为 img.src 时出现莫名其妙的后果//（相同环境有时能显示，有时不显示），因此只能用滤镜来解决 // IE7, IE8因安全性问题已无法直接通过 input[file].value 获取完整的文件路径sender.select();var imgSrc = document.selection.createRange().text; objPreviewFake.filters.item( DXImageTransform.Microsoft.AlphaImageLoader).src = imgSrc;objPreviewSizeFake.filters.item( DXImageTransform.Microsoft.AlphaImageLoader).src = imgSrc; autoSizePreview( objPreviewFake, objPreviewSizeFake.offsetWidth, objPreviewSizeFake.offsetHeight );objPreview.style.display = one; } } function onPreviewLoad(sender){ autoSizePreview( sender, sender.offsetWidth, sender.offsetHeight ); } function autoSizePreview( objPre, originalWidth, originalHeight ){ var zoomParam = clacImgZoomParam( 300, 300, originalWidth, originalHeight ); objPre.style.width = zoomParam.width + px; objPre.style.height = zoomParam.height + px; objPre.style.marginTop = zoomParam.top + px; objPre.style.marginLeft = zoomParam.left + px; } function clacImgZoomParam( maxWidth, maxHeight, width, height ){ var param = { width:width, height:height, top:0, left:0 }; if( width>maxWidth || height>maxHeight ){rateWidth = width / maxWidth;rateHeight = height / maxHeight; if( rateWidth > rateHeight ){ param.width = maxWidth; param.height = height / rateWidth;}else{ param.width = width / rateHeight; param.height = maxHeight;} } param.left = (maxWidth - param.width) / 2; param.top = (maxHeight - param.height) / 2; return param; }
