Griffin PowerMater as library wheel & preview button - Mixxx HID controller mappings

griffin-powermate-library-control.hid.js

const THROTTLE = 50;
const GPM = { lastMove: null, previewToMiddleOnLoad: false };
const GROUPS = { PREVIEW: "[PreviewDeck1]" };
const MAX_POSITION = 1.14;

GPM.init = function (id) {
  GPM.controller = new HIDController();
  GPM.id = id;
  GPM.registerInputPackets();
  GPM.registerOutputPackets();
  GPM.registerCallbacks();
  engine.makeConnection(
    GROUPS.PREVIEW,
    "track_loaded",
    GPM.handlePreviewLoaded
  );
  GPM.toggleLED(false);
};

GPM.shutdown = function () {
  GPM.controller.close();
};

GPM.registerOutputPackets = function () {
  const packet = new HIDPacket("out");

  packet.addControl("hid", "led", 0, "B");

  GPM.controller.registerOutputPacket(packet);
};

GPM.handlePreviewLoaded = function () {
  if (GPM.previewToMiddleOnLoad) {
    GPM.previewToMiddleOnLoad = false;
    engine.setValue(GROUPS.PREVIEW, "playposition", MAX_POSITION / 2);
  }
};

GPM.startPreview = function () {
  const playing = engine.getValue(GROUPS.PREVIEW, "play");

  GPM.previewToMiddleOnLoad = true;
  GPM.toggleLED(true);
  script.triggerControl(GROUPS.PREVIEW, "LoadSelectedTrackAndPlay", true);
};

GPM.stopPreview = function () {
  GPM.toggleLED(false);
  return engine.setValue(GROUPS.PREVIEW, "play", false);
};

GPM.registerInputPackets = function () {
  const packet = new HIDPacket("control");

  packet.addControl("hid", "button", 0, "B", 0x01);
  packet.addControl("hid", "wheel", 1, "b");
  packet.setMinDelta("hid", "wheel", undefined);

  this.controller.registerInputPacket(packet);
};

GPM.incomingData = function (data, length) {
  GPM.controller.parsePacket(data, length);
};

GPM.registerCallbacks = function (id) {
  const controller = GPM.controller;

  controller.setCallback("control", "hid", "button", GPM.button);
  controller.setCallback("control", "hid", "wheel", GPM.wheel);
};

GPM.toggleLED = function (on) {
  const packet = GPM.controller.getOutputPacket("out");
  const field = packet.getField("hid", "led");

  field.value = on ? 255 : 0;

  packet.send();
};

GPM.button = function (field) {
  field.value ? GPM.startPreview() : GPM.stopPreview();
};

GPM.wheel = function (field) {
  if (field.value === 0) {
    return;
  }

  if (GPM.lastMove && Date.now() - GPM.lastMove < THROTTLE) {
    return;
  }

  GPM.lastMove = Date.now();

  script.triggerControl(
    "[Playlist]",
    field.value > 0 ? "SelectNextTrack" : "SelectPrevTrack",
    true
  );
};

griffin-powermate-library-control.hid.xml

<?xml version='1.0' encoding='utf-8'?>
<MixxxControllerPreset schemaVersion="1" mixxxVersion="1.11+">
    <info>
        <name>Griffin Powermate - Library control</name>
        <author>Tancredi Trugenberger</author>
        <description>Griffin Powermate HID mapping to library control (press to preview track)</description>
    </info>
    <controller id="Griffin">
        <scriptfiles>
            <file filename="common-hid-packet-parser.js" functionprefix=""/>
            <file filename="griffin-powermate-library-control.hid.js" functionprefix="GPM"/>
        </scriptfiles>
    </controller>
</MixxxControllerPreset>