saveqrcode() {
                var that = this
                uni.canvasToTempFilePath({
                    canvasId: 'myQrcode', // canvas 标签的 id 或 canvas-id
                    success: function(res) {
                        // 在H5平台下，tempFilePath 为 base64
                        console.log(res) // 生成的临时路径
                        var tempFilePath = res.tempFilePath;
                        uni.saveImageToPhotosAlbum({
                            filePath: tempFilePath,
                            success: function() {
                                console.log('save success');
                            }
                        });
                    }
                })
            }