First off, if you don't know what launchpad is, visit:
Novation's site at de.novationmusic.com/products/midi_controller/launchpad
my demo videos for this library at www.youtube.com/thomasjachmann
other demos on youtube www.youtube.com/results?search_query=novation+launchpad
This gem provides an interface to access novation's launchpad programmatically. LEDs can be lighted and button presses can be responded to. Internally, launchpad's MIDI input/output is used to accomplish this.
The interfaces should be rather stable now (sorry, I changed quite a bit since the last release), so experiment with them and comment on their usability. This still is work in progress. If you need anything or think the interfaces could be improved in any way, please contact me.
Sometimes, the launchpad won't react to anything or react to/light up the wrong LEDs. Don't despair, just dis- and reconnect the thing. It seems that some (unexpected) MIDI signals make it hickup.
The gem is hosted on Gemcutter, so in order to use it, you're gonna install the gemcutter gem (for details, see their site):
gem install gemcutter gem tumble
After that, it's a simple gem install:
gem install launchpad
There are two main entry points:
require 'launchpad/device', providing Launchpad::Device, which handles all the basic input/output stuff
require 'launchpad/interaction' or just 'launchpad', additionally providing Launchpad::Interaction, which lets you respond to actions (button presses/releases)
This is a simple example (only requiring the device for output) that switches on all LEDs (for testing), resets the launchpad again and then lights the grid button at position 4/4 (from top left).
require 'rubygems' require 'launchpad/device' device = Launchpad::Device.new device.test_leds sleep 1 device.reset sleep 1 device.change :grid, :x => 4, :y => 4, :red => :high, :green => :low
This is an interaction example lighting all grid buttons in red when pressed and keeping them lit.
require 'rubygems' require 'launchpad' interaction = Launchpad::Interaction.new interaction.response_to(:grid, :down) do |interaction, action| interaction.device.change(:grid, action.merge(:red => :high)) end interaction.response_to(:mixer, :down) do |interaction, action| interaction.stop end interaction.start
For more details, see the examples. examples/color_picker.rb is the most complex example with interaction.
Near future plans
interaction responses for presses on single grid buttons/button areas
internal tracking of LED states for both buffers
single threading fix: prevent ThreadError when Launchpad::Interaction#stop is called within an action response
Launchpad::Interaction#close now properly stops interaction first
multi threading: Launchpad::Interaction#start method can be called with :detached => true to allow calling thread to continue
double buffering (see Launchpad::Device#buffering_mode)
don't update grid button 0,0 before change_all (in order to reset rapid update pointer), use MIDI message without visual effect
(at least) doubled the speed of change_all by not sending each message individually but sending them in one go (as an array)
ability to close device/interaction to free portmidi resources
ability to initialize devices using device ids as well as device names
complete documentation for rdoc.info/projects/thomasjachmann/launchpad
first feature complete version with kinda stable API
Copyright © 2009 Thomas Jachmann. See LICENSE for details.