CharacteristicWrapper.js

class CharacteristicWrapper {
  constructor(rawCharacteristic) {
    this.rawCharacteristic = rawCharacteristic
    this.uuid = rawCharacteristic.uuid.replace(/-/g, "")
    this.properties = ["notify"]
  }

  toBuffer(ab) {
    var buf = toio.scanner.Buffer.alloc(ab.byteLength);
    var view = new Uint8Array(ab);
    for (var i = 0; i < buf.length; ++i) {
      buf[i] = view[i];
    }
    return buf;
  }

  on(id, e) {
    if (id == 'data') {
      this.rawCharacteristic.addEventListener('characteristicvaluechanged', message => {
        e(this.toBuffer(message.target.value.buffer))
      })
    }
    else {
      console.log(`unknown event ${id}`)
    }
  }

  subscribe(e) {
    if (e != undefined) {
      this.rawCharacteristic.startNotifications().then(_ => {
        e()
      })
    } else {
      this.rawCharacteristic.startNotifications()
    }
  }

  unsubscribe(e) {
    if (e != undefined) {
      this.rawCharacteristic.stopNotifications().then(_ => {
        e()
      })
    } else {
      this.rawCharacteristic.stopNotifications()
    }
  }

  write(data) {
    this.rawCharacteristic.writeValue(data)
  }
}