base64 压缩图片

//图片处理

afterimg(err, photos) {

var _this = this;

if(err && err != null && err != '') {

return ;

}

var src = 'data:image/jpeg;base64,' + photos;

var inputData = {

fileName: ["upload", '_', new Date().getTime(), '_', Math.floor(Math.random() * 1000000), '.png'].join(''), // 文件全名，包括格式

fileContent: src

};

var width = parseInt(document.documentElement.clientWidth) * 0.8;

_this.dealImage(src, {

width: width

}, inputData, _this.uploadimage);

},

//压缩图片

dealImage(path, obj, data, cb) {

var img = new Image();

img.src = path;

img.onload = function() {

var that = this;

// 默认按比例压缩

var w = that.width,

h = that.height,

scale = w / h;

w = obj.width || w;

h = obj.height || (w / scale);

var quality = 0.75; // 默认图片质量为0.7

//生成canvas

var canvas = document.createElement('canvas');

var ctx = canvas.getContext('2d');

// 创建属性节点

var anw = document.createAttribute("width");

anw.nodeValue = w;

var anh = document.createAttribute("height");

anh.nodeValue = h;

canvas.setAttributeNode(anw);

canvas.setAttributeNode(anh);

ctx.drawImage(that, 0, 0, w, h);

// 图像质量

if(obj.quality && obj.quality <= 1 && obj.quality > 0) {

quality = obj.quality;

}

var base64 = canvas.toDataURL('image/jpeg', quality).replace('data:image/jpeg;base64,', '');

// 回调函数返回base64的值

data.fileContent = base64;

typeof cb == 'function' && cb(data);

}

},

//上传图片

uploadimage(inputData) {}