ble-server/gdata-characteristic.js

const bleno = require('bleno')
const config = require('./config.json')
const escpos = require('escpos')
const device = escpos.Serial(config.printer.serial)
const printer = escpos.Printer(device)
let isOpen = false

device.open(()=>{
  isOpen = true
})

var tmp = []

const notifyDesciptor = new bleno.Descriptor({
  uuid: '8888',
  value: 0
})

class DataCharacteristic extends bleno.Characteristic {
  constructor() {
    super({
      uuid: config.uuid.service.func.data,
      properties: ['write', 'writeWithoutResponse', 'notify'],
      descriptors: [
        notifyDesciptor
      ]
    })
    this._notifyFunc = null
  }

  onWriteRequest(data, offset, withoutResponse, callback) {
    console.log(`offset :: ${offset} , withoutRes :: ${withoutResponse}`)
    console.log(`get data`, data)

    if (data.length == 1 && data[0] == 0x00) {
      tmp = []
      console.log(data[0])
    } else if (data.length == 1 && data[0] == 0xff) {
      //console.log(tmp)
      console.log(Buffer.from(tmp).toString())
      printString(Buffer.from(tmp).toString())
      if(this._notifyFunc) {
        this._notifyFunc(Buffer.from([0x00,0x01]))
      }
    } else {
      tmp = [...tmp, ...data.slice(2, data.length)]
    }
    if (!withoutResponse) {
      console.log('send response')
      callback(this.RESULT_SUCCESS)
    }
  }

  onSubscribe(maxValueSize, cb) {
    console.log(maxValueSize)
    this._notifyFunc = cb
  }

  onUnsubscribe () {
    this._notifyFunc = null
  }
}


function printString(str){
  if(!isOpen) return 
  let strs = str.split(/\n/)
  printer.font('a')
    .align('ct')
    .size(1,1)
  for(let i in strs){
    printer.text(strs[i])
  }
  printer.cut(true, 8)
}

module.exports = DataCharacteristic