Robert Kaiser, "KaiRo" <kairo@kairo.at>
Program Manager, Mozilla QA

Sensor device as seen on "Star Trek"

Displays whatever data is needed at plot speeds and resolutions.

Displays data from device sensors as exposed by WebAPIs

marketplace.firefox.com/app/tricorder/

Code: github.com/KaiRo-at/tricorder

• HTML (switch, display)
• JS Object
  • 2 Methods: activate(), deactivate()

GPS, WiFi/Cell Location

API: Geolocation

Permission: geolocation

  this.watchID = navigator.geolocation.watchPosition(
    function(position) {
      position.coords.latitude / .longitude / .accuracy / ...
    },
    function(error) { ... },
    {enableHighAccuracy: true, maximumAge: 10000, timeout: 60000}
  );

  navigator.geolocation.clearWatch(this.watchID);

Accelerometer, Magnetometer

APIs: deviceorientation, devicemotion events

Permissions: ---

  window.addEventListener("deviceorientation", this.orientEvent, true);
  window.addEventListener("devicemotion", this.motionEvent, true);

  orientEvent: function(orientData) {
    orientData.alpha / .beta / .gamma (in °)
  },
  motionEvent: function(event) {
    event.accelerationIncludingGravity.x / .y / .z (in m/s²)
  },

  window.removeEventListener("deviceorientation", this.orientEvent, true);
  window.removeEventListener("devicemotion", this.motionEvent, true);

Microphone

APIs: WebRTC(getUserMedia), WebAudio

Permissions: audio-capture

  navigator.getUserMedia({ audio: true },
    function(aLocalMediaStream) {
      gModSound.mAudio.stream = aLocalMediaStream;
      gModSound.mAudio.context = new window.AudioContext();
      gModSound.mAudio.input =
          gModSound.mAudio.context.createMediaStreamSource(gModSound.mAudio.stream);
      gModSound.mAudio.analyzer = gModSound.mAudio.context.createAnalyser();
      gModSound.mAudio.input.connect(gModSound.mAudio.analyzer);
    },
    function(err) { ... }
  );

  // in window.requestAnimationFrame():
  var data = new Uint8Array(gModSound.mAudio.frequencySlices);
  gModSound.mAudio.analyzer.getByteFrequencyData(data);
  // ... do something with data ...

  gModSound.mAudio.stream.stop();

Light, Proximity; Flashlight

APIs: devicelight, deviceproximity events; Camera API

Permissions: ---; camera (for Flash)

  window.addEventListener("devicelight", this.lightEvent, true);
  window.addEventListener("deviceproximity", this.proxEvent, true);

  lightEvent: function(lightData) {
    lightData.value (in lux)
  },
  proxEvent: function(proxData) {
    proxData.min <= .value <= .max (in cm)
  },

  window.removeEventListener("devicelight", this.lightEvent, true);
  window.removeEventListener("deviceproximity", this.proxEvent, true);

  // flash/torch code works via navigator.mozCameras.getCamera
  // flaky and subject to change, please consult code on github

Battery

APIs: Battery Status API

Permissions: ---

  0 <= navigator.battery.level <= 1

  .charging (true/false)

  .chargingTime (in s; 0 or Infinity: unknown)

  .dischargingTime (in s; 0 or Infinity: unknown)

Questions?