upImg(){
	var that = this;
	uni.chooseImage({
	    count: 6, //默认9
	    sizeType: ['original', 'compressed'], //可以指定是原图还是压缩图，默认二者都有
	    sourceType: ['album'], //从相册选择
	    success: function (res) {
			if(res.errMsg=='chooseImage:ok'){
				console.log(res);
				console.log(res.tempFiles[0].path);
				that.urlTobase64(res.tempFiles[0].path);
				that.upimg = res.tempFiles[0].path;
			}
	    }
	});
},
urlTobase64(url) {
	var that = this;
	uni.request({
		url: url,
		method: 'GET',
		responseType: 'arraybuffer',
		success: res => {
			let base64 = wx.arrayBufferToBase64(res.data); //把arraybuffer转成base64
			that.image_1920 = base64;
			base64 = 'data:image/jpeg;base64,'+base64; //不加上这串字符，在页面无法显示
			console.log('base64->',base64);
		}
	});
},