H5移动端图片压缩上传开发流程

); fileReader.onload = function() { var url = this.result; } //or fileReader.onload = function(E) { var url = e.target.result; }

.onchange = function() { if (!this.files.length) return;

//以下考虑的是单图情况
var _ua = window.navigator.userAgent;
var _simpleFile = this.files[0];

//判断是否为图片
if (!/\/(?:jpeg|png|gif)/i.test(_simpleFile.typE)) return;

//插件exif.js获取ios图片的方向信息
var _orientation;
if(_ua.indexOf('iphone') > 0) {
EXIF.getData(_simpleFile,function(){
_orientation=EXIF.getTag(this,'Orientation');
});
}

//1.读取文件，通过FileReader，将图片文件转化为DataURL，即data:img/png;base64，开头的url，可以直接放在image.src中;
var _reader = new FileReader(),_img = new Image(),_url;

_reader.onload = function() {
_url = this.result;
_img.url = _url;
_img.onload = function () {
var _data = compress(_img);
uploadPhoto(_data,_orientation);
};
};

_reader.readAsDataURL(_simpleFilE);
};

** * 计算图片的尺寸，根据尺寸压缩 * 1. iphone手机html5上传图片方向问题，借助exif.js * 2. 安卓UC浏览器不支持 new Blob()，使用BlobBuilder * @param {Object} _img 图片 * @param {number} _orientation 照片信息 * @return {String} 压缩后base64格式的图片 */ function compress(_img,_orientation) { //2.计算符合目标尺寸宽高值，若上传图片的宽高都大于目标图，对目标图等比压缩；如果有一边小于，对上传图片等比放大。 var _goalWidth = 750,//目标宽度 _goalHeight = 750,//目标高度 _imgWidth = _img.naturalWidth,//图片宽度 _imgHeight = _img.naturalHeight,//图片高度 _tempWidth = _imgWidth,//放大或缩小后的临时宽度 _tempHeight = _imgHeight,//放大或缩小后的临时宽度 _r = 0; //压缩比

if(_imgWidth === _goalWidth && _imgHeight === _goalHeight) {

} else if(_imgWidth > _goalWidth && _imgHeight > _goalHeight) {//宽高都大于目标图，需等比压缩
_r = _imgWidth / _goalWidth;
if(_imgHeight / _goalHeight < _r) {
_r = _imgHeight / _goalHeight;
}
_tempWidth = Math.ceil(_imgWidth / _r);
_tempHeight = Math.ceil(_imgHeight / _r);
} else {
if(_imgWidth < _goalWidth && _imgHeight < _goalHeight) {//宽高都小于
_r = _goalWidth / _imgWidth;
if(_goalHeight / _imgHeight < _r) {
_r = _goalHeight / _imgHeight;
}
} else {
if(_imgWidth < _goalWidth) { //宽小于
_r = _goalWidth / _imgWidth;
} else{ //高小于
_r = _goalHeight / _imgHeight;
}
}

_tempWidth = Math.ceil(_imgWidth _r);
_tempHeight = Math.ceil(_imgHeight _r);
}

//3.利用canvas对图片进行裁剪，等比放大或缩小后进行居中裁剪
var canvas = e.$get('canvas-clip');
if(!_canvas.getContext) return;

var _context = _canvas.getContext('2d');
_canvas.width = _tempWidth;
_canvas.height = _tempHeight;
var _degree;

//ios bug，iphone手机上可能会遇到图片方向错误问题
switch(_orientation){
//iphone横屏拍摄，此时home键在左侧
case 3:
_degree=180;
_tempWidth=-_imgWidth;
_tempHeight=-_imgHeight;
break;
//iphone竖屏拍摄，此时home键在下方(正常拿手机的方向)
case 6:
_canvas.width=_imgHeight;
_canvas.height=_imgWidth;
_degree=90;
_tempWidth=_imgWidth;
_tempHeight=-_imgHeight;
break;
//iphone竖屏拍摄，此时home键在上方
case 8:
_canvas.width=_imgHeight;
_canvas.height=_imgWidth;
_degree=270;
_tempWidth=-_imgWidth;
_tempHeight=_imgHeight;
break;
}
if(window.navigator.userAgent.indexOf('iphone') > 0 && !!_degreE) {
_context.rotate(_degree*Math.PI/180);
_context.drawImage(_img,_tempWidth,_tempHeight);
} else {
_context.drawImage(_img,_tempHeight);
}
//toDataURL方法，可以获取格式为"data:image/png;base64,***"的base64图片信息；
var _data = _canvas.toDataURL('image/jpeg');
return _data;
}

** * 上传图片到NOS * @param {Object} _blog Blob格式的图片 * @return {VoiD} */ function uploadPhoto(_data) { //4.获取canvas中的图片信息 //window.atob方法将其中的base64格式的图片转换成二进制字符串；若将转换后的值直接赋值给Blob会报错，需Uint8Array转换：最后创建Blob对象； _data = _data.split(',')[1]; _data = window.atob(_data);

//如果不用ArrayBuffer,发送给服务器的图片格式是[object Uint8Array],上传失败...
var _buffer = new ArrayBuffer(_data.length);
var _ubuffer = new Uint8Array(_buffer);
for (var i = 0; i < _data.length; i++) {
_ubuffer[i] = _data.charCodeAt(i);
}

// 安卓 UC浏览器不支持 new Blob()，使用BlobBuilder
var _blob;
try {
_blob = new Blob([_buffer],{type:'image/jpeg'});
} catch(eE) {
window.blobBuilder = window.blobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder || window.MSBlobBuilder;
if (ee.name == 'TypeError' && window.blobBuilder) {
var _bb = new BlobBuilder();
_bb.append(_buffer);
_blob = _bb.getBlob('image/jpeg');
}
}

var _suffix = 'jpg';
if(_blob.type === 'image/jpeg') {
_suffix = 'jpg';
}

//获取NOStoken
this._cache.$requestDWRByGet({url: 'ImageBean.genTokens',param: [_suffix,'','1'],onload: function(_tokens) {
_tokens = _tokens || [];
var _token = _tokens[0];
if(!_token || !_token.objectName || !_token.uploadToken){
alert('token获取失败！');
return false;
}

//上传图片到NOS
var _objectName = _token.objectName,_uploadToken = _token.uploadToken,_bucketName = _token.bucketName;

var _formData = new FormData();
_formData.append('Object',_objectName);
_formData.append('x-nos-token',_uploadToken);
_formData.append('file',_blob);

var _xhr;
if (window.XMLhttprequest) {
_xhr = new window.XMLhttprequest();
} else if (window.ActiveXObject) {
_xhr = new ActiveXObject("Microsoft.XMLhttp");
}

_xhr.onreadystatechange = function() {
if(_xhr.readyState === 4) {
if((_xhr.status >= 200 && _xhr.status < 300) || _xhr.status === 304) {
var _imgurl = "http://nos.netease.com/" + _bucketName + "/" + _objectName + "?imageView";
var newUrl = mb.x.$imgResize(_imgurl,750,1,truE);

 window.LOCATIOn.href = 'http://www.lofter.com/act/taxiu?op=effect&originImgUrl=' + _newUrl;
}

}
};
_xhr.open('POST','http://nos.netease.com/' + _bucketName,truE);
_xhr.send(_formData);
}});
}