<!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>Firefox3,IE6,IE7,IE8上传图片预览</title> <style type="text/css"> #preview_wrapper{ width:300px; height:300px; border:1px solid #ccc; } #preview_fake{ /* 该对象用于在IE下显示预览图片 */ filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale); } #preview_size_fake{ /* 该对象只用来在IE下获得图片的原始尺寸，无其它用途 */ filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image); visibility:hidden; } #preview{ /* 该对象用于在FF下显示预览图片 */ display: block; width:auto; height:auto; } </style> </head> <body> <div id="preview_wrapper"> <div id="preview_fake"> <img id="preview" src="../image/default.jpg" onload="onPreviewLoad(this)"/> </div> </div><br /> <input id="upload_img" type="file" onchange="onUploadImgChange(this)"/> <br/> <img id="preview_size_fake"/> <script type="text/javascript"> //上传文件 function onUploadImgChange(sender){ //单纯只为了文件名 var filePath = sender.value; var fileExt = filePath.substring(filePath.lastIndexOf(".")).toLowerCase(); if(!checkFileExt(fileExt)){ alert("您上传的文件不是图片,请重新选择！"); return; } var objPreview = document.getElementById( 'preview' ); objPreviewFake = document.getElementById( 'preview_fake' ), objPreviewSizeFake = document.getElementById( 'preview_size_fake' ); try{ //先采用HTML5方法 if(typeof FileReader !== 'undefined'){ var file = sender.files[0]; var fileSize = file.fileSize || file.size; if(checkFileSize(fileSize)){ var reader = new FileReader(); reader.readAsDataURL(file); reader.onload = function(e){ objPreview.src = this.result; } } }else if( sender.files){ //非IE，不支持HTML5方法 var file = sender.files[0]; fileSize = file.fileSize; if(checkFileSize(fileSize)){ filePath = file.getAsDataURL(); objPreview.src = filePath; } }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 = 'none'; //读取图片文件大小 var sh = setInterval(function(){ var img = document.createElement("img"); img.src = imgSrc; fileSize = img.fileSize; if (fileSize > 0){ checkFileSize(fileSize); clearInterval(sh); } img = null; } ,100); } }catch(e){ alert("调用后台方法"); } } //检测文件类型 function checkFileExt(ext){ if (!ext.match(/.jpg|.gif|.png|.bmp/i)) { return false; } return true; } //检测文件大小 function checkFileSize(fileSize){ if(fileSize > 1024*1024){ alert("子函数：您上传的文件大于1M,请重新选择！"); return false; } return true; } //预览 function onPreviewLoad(sender){ autoSizePreview( sender, sender.offsetWidth, sender.offsetHeight ); } //居中显示 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'; } //图像缩放 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; } </script> </body> </html>
