当前位置:
首页 > 技术 > 纯js 图片上传本地预览及图片大小格式限制判断

纯js 图片上传本地预览及图片大小格式限制判断

猛戳我查看效果

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>图片上传本地预览及图片大小格式限制判断</title>

<style type="text/css">
#preview{width:260px;height:190px;border:1px solid #000;overflow:hidden;background-color:#eee;border:1px
solid #ddd;text-align: center;} #imghead {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);}
.upload{margin-top:10px;}
</style>

<script type="text/javascript">
//图片上传预览 IE是用了滤镜。
function previewImage(file) {
getPhotoSize(file);

var MAXWIDTH = 260;
var MAXHEIGHT = 180;
var div = document.getElementById('preview');

if (file.files && file.files[0]) {
div.innerHTML = '<img id=imghead>';
var img = document.getElementById('imghead');
img.onload = function() {
var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
img.width = rect.width;
img.height = rect.height;
//img.style.marginLeft = rect.left+'px';
img.style.marginTop = rect.top + 'px';
}
var reader = new FileReader();
reader.onload = function(evt) {
img.src = evt.target.result;
}
reader.readAsDataURL(file.files[0]);
} else //兼容IE
{
var sFilter = 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
file.select();
var src = document.selection.createRange().text;
div.innerHTML = '<img id=imghead>';
var img = document.getElementById('imghead');
img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
status = ('rect:' + rect.top + ',' + rect.left + ',' + rect.width + ',' + rect.height);
div.innerHTML = "<div id=divhead style='width:" + rect.width + "px;height:" + rect.height + "px;margin-top:" + rect.top + "px;" + sFilter + src + "\"'></div>";
}
}
function clacImgZoomParam(maxWidth, maxHeight, width, height) {
var param = {
top: 0,
left: 0,
width: width,
height: height
};
if (width > maxWidth || height > maxHeight) {
rateWidth = width / maxWidth;
rateHeight = height / maxHeight;

if (rateWidth > rateHeight) {
param.width = maxWidth;
param.height = Math.round(height / rateWidth);
} else {
param.width = Math.round(width / rateHeight);
param.height = maxHeight;
}
}

param.left = Math.round((maxWidth - param.width) / 2);
param.top = Math.round((maxHeight - param.height) / 2);
return param;
}

//判断照片大小
function getPhotoSize(obj) {
photoExt = obj.value.substr(obj.value.lastIndexOf(".")).toLowerCase(); //获得文件后缀名
var $formate = ['jpg', 'gif', 'jpeg', 'png', 'bmp'],
$formate_error = false;
for (var k in $formate) {
if (photoExt != $formate[k]) {
$formate_error = true;
}
}

if (!$formate_error) {
alert("请上传后缀名为 jpg、gif、jpeg、png、bmp 的照片!");
return false;
}

var fileSize = 0;
var isIE = /msie/i.test(navigator.userAgent) && !window.opera;
if (isIE && !obj.files) {
var filePath = obj.value;
var fileSystem = new ActiveXObject("Scripting.FileSystemObject");
var file = fileSystem.GetFile(filePath);
fileSize = file.Size;
} else {
fileSize = obj.files[0].size;
}
fileSize = Math.round(fileSize / 1024 * 100) / 100; //单位为KB
if (fileSize >= 10) {
alert("照片最大尺寸为10KB,请重新上传!");
return false;
}
}
</script>
</head>

<body>

<div id="preview">
<img id="imghead" src=''>
</div>
<input type="file" class="upload" onchange="previewImage(this)" />

</body>

</html>

纯js 图片上传本地预览及图片大小格式限制判断:等您坐沙发呢!

发表评论

您必须 [ 登录 ] 才能发表留言!