ble-server/PrinterDev.js

const EventEmitter = require('events')
const escpos = require('escpos')
const config = require('./config.json')
const fs = require('fs')
const iconv = require('iconv-lite')

class PrinterDevice {
  constructor() {
    this._isOpen = false
    this._device = null
    this._printer = null
    this._type = null // type = serial or console
  }

  encodeStr(str){
    if(!str || typeof str != 'string') return false
    return iconv.encode(str, 'big5')
  }

  async connect() {
    let chkSerial = await new Promise((resolve, reject) => {
      fs.access(config.printer.serial, err => {
        if (err) return resolve(false)
        return resolve(true)
      })
    })
    if (chkSerial) {
      this._device = new escpos.Serial(config.printer.serial)
      this._type = 'serial'
    } else {
      this._device = new escpos.Console()
      this._type = 'console'
    }
    this._printer = new escpos.Printer(this._device)
    this.openSerial()
  }

  async openSerial() {
    if (!this._device || this._type != 'serial') return
    this._isOpen = await new Promise((resolve, reject) => {
      this._device.open(err => {
        if (err) return resolve(false)
        return resolve(true)
      })
    })
  }

  async printerString(str) {
    if (!this._isOpen || !this._printer) return false

    this._printer.font('a')
      .align('ct')
      .size(1, 1)

    let cmds = str.split(/__/).filter(t => t)

    for (let i in cmds) {
      let tmp = cmds[i]
      if (tmp[0] === '&') {
        switch (tmp[1]) {
          case 'a':
            let align = tmp.substring(2)
            if (!align) break
            this._printer.align(align)
            break
          case 's':
            let size = tmp.substring(2)
            let sarr = size.trim().split(',')
            if (sarr != 2) break
            if(!isFinite(sarr[0]) || !isFinite(sarr[1])) break
            sarr = sarr.map(t => Math.floor(t))
            this._printer.size(sarr[0], sarr[1])
            break
        }
      } else {
        this._printer.print(this.encodeStr(tmp))
      }
    }

    this._printer.cut(true, config.printer.cutFeed || 4)

    return true
  }

  async close() {
    if (!this._device) return
    if (this._type == 'serial') {
      let self = this
      await new Promise((resolve, reject) => {
        self._printer.close(() => {
          resolve(1)
        })
      })
    }
  }

  get isOpen() {
    return this._isOpen ? true : false
  }
}

module.exports = new PrinterDevice()