之前的移动端上传的方法，有些朋友测试说微信支持不是很好，还有部分安卓机也不支持，其实我已经有了另一个方法，但是例子还没整理出来，而联系我的很多朋友需要，所以就提前先发出来了，并且做一个简单的说明，就不做一个demo了。
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0">
<title>图片压缩</title>
<style>
body { margin:0; padding:0; }
html { font-size:62.5%; }
.imgzip { padding:1em; }
.imgzip .itm { padding-bottom:1em; word-break:break-all; font-size:1.2rem; line-height:1.5em; }
.imgzip .itm .tit { margin-bottom:.5em; background-color:#e71446; color:#FFF; padding:.5rem 1rem; border-radius:3px; }
.imgzip .itm .cnt { padding:1rem; }
.imgzip .itm .cnt img { display:block; max-width:100%; }
.imgzip textarea { width:100%; height:20em; }
</style>
</head>
<body>
<script src="http://code.jquery.com/jquery-1.8.3.js"></script>
<input type="file" accept="image/*;capture=camera" class="input">
<div class="imgzip"></div>
<script>
document.addEventListener(‘DOMContentLoaded‘, init, false);
function init() {
var u = new UploadPic();
u.init({
input: document.querySelector(‘.input‘),
callback: function (base64) {
$.ajax({
url:"{:U(‘upload‘)}",
data:{str:base64,type:this.fileType},
type:‘post‘,
dataType:‘json‘,
success:function(i){
alert(i.info);
}
})
},
loading: function () {
}
});
}
function UploadPic() {
this.sw = 0;
this.sh = 0;
this.tw = 0;
this.th = 0;
this.scale = 0;
this.maxWidth = 0;
this.maxHeight = 0;
this.maxSize = 0;
this.fileSize = 0;
this.fileDate = null;
this.fileType = ‘‘;
this.fileName = ‘‘;
this.input = null;
this.canvas = null;
this.mime = {};
this.type = ‘‘;
this.callback = function () {};
this.loading = function () {};
}
UploadPic.prototype.init = function (options) {
this.maxWidth = options.maxWidth || 800;
this.maxHeight = options.maxHeight || 600;
this.maxSize = options.maxSize || 3 * 1024 * 1024;
this.input = options.input;
this.mime = {‘png‘: ‘image/png‘, ‘jpg‘: ‘image/jpeg‘, ‘jpeg‘: ‘image/jpeg‘, ‘bmp‘: ‘image/bmp‘};
this.callback = options.callback || function () {};
this.loading = options.loading || function () {};
this._addEvent();
};
/**
* @description 绑定事件
* @param {Object} elm 元素
* @param {Function} fn 绑定函数
*/
UploadPic.prototype._addEvent = function () {
var _this = this;
function tmpSelectFile(ev) {
_this._handelSelectFile(ev);
}
this.input.addEventListener(‘change‘, tmpSelectFile, false);
};
/**
* @description 绑定事件
* @param {Object} elm 元素
* @param {Function} fn 绑定函数
*/
UploadPic.prototype._handelSelectFile = function (ev) {
var file = ev.target.files[0];
this.type = file.type
// 如果没有文件类型，则通过后缀名判断（解决微信及360浏览器无法获取图片类型问题）
if (!this.type) {
this.type = this.mime[file.name.match(/\.([^\.]+)$/i)[1]];
}
if (!/image.(png|jpg|jpeg|bmp)/.test(this.type)) {
alert(‘选择的文件类型不是图片‘);
return;
}
if (file.size > this.maxSize) {
alert(‘选择文件大于‘ + this.maxSize / 1024 / 1024 + ‘M，请重新选择‘);
return;
}
this.fileName = file.name;
this.fileSize = file.size;
this.fileType = this.type;
this.fileDate = file.lastModifiedDate;
this._readImage(file);
};
/**
* @description 读取图片文件
* @param {Object} image 图片文件
*/
UploadPic.prototype._readImage = function (file) {
var _this = this;
function tmpCreateImage(uri) {
_this._createImage(uri);
}
this.loading();
this._getURI(file, tmpCreateImage);
};
/**
* @description 通过文件获得URI
* @param {Object} file 文件
* @param {Function} callback 回调函数，返回文件对应URI
* return {Bool} 返回false
*/
UploadPic.prototype._getURI = function (file, callback) {
var reader = new FileReader();
var _this = this;
function tmpLoad() {
// 头不带图片格式，需填写格式
var re = /^data:base64,/;
var ret = this.result + ‘‘;
if (re.test(ret)) ret = ret.replace(re, ‘data:‘ + _this.mime[_this.fileType] + ‘;base64,‘);
callback && callback(ret);
}
reader.onload = tmpLoad;
reader.readAsDataURL(file);
return false;
};
/**
* @description 创建图片
* @param {Object} image 图片文件
*/
UploadPic.prototype._createImage = function (uri) {
var img = new Image();
var _this = this;
function tmpLoad() {
_this._drawImage(this);
}
img.onload = tmpLoad;
img.src = uri;
};
/**
* @description 创建Canvas将图片画至其中，并获得压缩后的文件
* @param {Object} img 图片文件
* @param {Number} width 图片最大宽度
* @param {Number} height 图片最大高度
* @param {Function} callback 回调函数，参数为图片base64编码
* return {Object} 返回压缩后的图片
*/
UploadPic.prototype._drawImage = function (img, callback) {
this.sw = img.width;
this.sh = img.height;
this.tw = img.width;
this.th = img.height;
this.scale = (this.tw / this.th).toFixed(2);
if (this.sw > this.maxWidth) {
this.sw = this.maxWidth;
this.sh = Math.round(this.sw / this.scale);
}
if (this.sh > this.maxHeight) {
this.sh = this.maxHeight;
this.sw = Math.round(this.sh * this.scale);
}
this.canvas = document.createElement(‘canvas‘);
var ctx = this.canvas.getContext(‘2d‘);
this.canvas.width = this.sw;
this.canvas.height = this.sh;
ctx.drawImage(img, 0, 0, img.width, img.height, 0, 0, this.sw, this.sh);
this.callback(this.canvas.toDataURL(this.type));
ctx.clearRect(0, 0, this.tw, this.th);
this.canvas.width = 0;
this.canvas.height = 0;
this.canvas = null;
};
</script>
</body>
</html>这个也是把图片转成了base64去传送，个人不建议去用js改变图片的大小，建议裁切缩放还是PHP来做吧。
this.maxWidth = options.maxWidth || 800;
this.maxHeight = options.maxHeight || 600;
this.maxSize = options.maxSize || 3 * 1024 * 1024;
this.input = options.input;
this.mime = {‘png‘: ‘image/png‘, ‘jpg‘: ‘image/jpeg‘, ‘jpeg‘: ‘image/jpeg‘, ‘bmp‘: ‘image/bmp‘};这一部分是对上传图片的配置，应该可以看懂，可以自己去改
$.ajax({
url:"{:U(‘upload‘)}",
data:{str:base64,type:this.fileType},
type:‘post‘,
dataType:‘json‘,
success:function(i){
alert(i.info);
}这部分是上传以后ajax发送base64码到php,
base64码带有图片的说明字符串，所以得用正则去掉，然后base64解码保存到图片的文件中。并且返回地址即可
原文地址：http://a3147972.blog.51cto.com/2366547/1554698
