Launchpad.js

Interact with your launchpads in Node.js

Launchpad running an example script

This project started as a module for my own stream system to make several things interact with OBS studio, named rewards-interaction. After re-writing a broken launchpad library I decided to release the library to the public so everyone can enjoy easy programming on their launchpad.

Some sample programs can be found in the examples folder.

Launchpad models currently supported

• Launchpad MK2
• Launchpad MK3 (only tested with Mini)

Why are only these launchpads supported?

These launchpads are supported because I own them myself and have been able to test them. If a launchpad is not listed here it means that I do not own one and have not been able to test that one with the program.

Examples

More examples can be found in the examples folder, this is just a simple button listener.

const { autoDetect, colors } = require('launchpad.js');
const { colorFromHex, defaultColors } = colors;

const lp = autoDetect();

// Alternatively:
//
//    await waitForReady(lp);

lp.once('ready', (deviceName) => {
  console.log(`${deviceName} is ready!!`);

  lp.on('buttonDown', (button) => {
    // Generate a random color on each button press
    const randHex = Math.floor(Math.random() * 16777215).toString(16);

    // The Launchpad accepts an RGB-triple between 0 and 1. This converts the
    // hex code to the appropriate number array.
    const color = colorFromHex(randHex);

    console.log(`Button pressed ${button.nr} (x: ${button.xy[0]}, y: ${button.xy[1]}`);

    lp.setButtonColor(button, color);
  });

  lp.on('buttonUp', (button) => {
    lp.setButtonColor(button, defaultColors.off);
  });
});

Low-level API

A number of methods are available to control the button colors on the LaunchPad. In all of these methods, the button to control can be specified in one of the following ways:

• number, indicating a Launchpad-specific button number
• [x, y], a Launchpad-independent button coordinate with (0, 0) in the top-left.
• Button, a Button object (as returned by the buttonDown or buttonUp event handlers).

The follow methods control a button's color:

• lp.setButtonColor(button, colorOrRGB): set a button to a solid color. colorOrRGB is either:
  • number between 0..127, a color in the 128-color palette of the Launchpad.
  • [r, g, b], an array of RGB values between 0 and 1.
• lp.flash(button, color, colorB?): flash a button between two palette colors. For colors that don't support a second color, the button will flash to black.
• lp.pulse(button, color): a button will pulse between black and the given palette color.

Surface API

There is also a buffer-oriented API you can use, which works much like how graphics cards work. The class Surface addresses the Launchpad grid as one or more layers of 9x9 buttons. You can set and get the individual button styles, and call update() to send all changes to the Launchpad.

A helper class Drawing exists to help with performing common drawing operations.

See the examples/surface.js example for more information on how to use this API.

TODO

• Add support for the same launchpads as launchpad.py

Links

• Launchpad developer manual

Notice

This project contains modified code from https://github.com/Lokua/launchpad which was released under the MIT license