drummachine.rb

#
# A try to built a simple drummachine using Shoes and Midiator.
# Unfortunalty animation seems to be quite processor heavy. Things might get slow..
# Because of that, the beats don't get highlighted on beat. 
#
# You will need a midi input for this. 
# On OSX you could use http://notahat.com/midi_patchbay
# and http://notahat.com/simplesynth or Garage Band
# 
# Usage:
# Klick to toggle beat
# Press SPACE to start/stop the loop
#
# Andreas Haller (http://github.com/ahaller)
# enjoy.

# One Square representing a Beat
class Shoes::Beatbutton < Shoes::Widget
  attr :options
  
  def initialize(o = {})
    # FIXME Move this maybe out of here!? Widget should be "gui-only"!?
    # options
    @options = {
      :selected => false,
      :note => 48,
      :channel => 0,
      :duration => 1.5
    }.merge!(o)
    @selected = @options[:selected]
    
    # styling
    self.style :width => 25, :height => 25  # FIXME delete (?)
    strokewidth 4   
         
    # draw beat
    stack :width => 25, :height => 25 do    
      draw_boxes      
      click  do
        toggle
      end
    end      
  end
  
  def selected?
    @selected
  end
  
  def toggle
    @box_selected.toggle
    @selected = !@selected
  end
  
  private
  
  def draw_boxes
    fill gray; nostroke
    @box = box
    
    fill white
    @box_selected = box
    @box_selected.hide
  end
  
  # drawing a box
  def box    
    rect(0,0,25,25,4)
  end
end

# A row of beats
class Shoes::Track < Shoes::Widget
  attr :beats
  
  def initialize(o = {})
    @options = {
      :beat => {}
    }.merge!(o)
    @beats = []
    flow do
      16.times do
        @beats << beatbutton(@options[:beat].clone)
      end      
    end    
  end  
end

# Run the Shoes app
Shoes.setup do
  gem 'midiator >= 0.2.0' 
end

require 'midiator'

# Run the shoes app
Shoes.app :width => 420, :height => 130, :margin => 10, :resizable => false do 
  # Setup midi driver
  @midi = MIDIator::Interface.new
  @midi.autodetect_driver
  @midi.program_change 0, 25 # Electronic Drumset
  
  # Tempo
  @tempo = 8
  
  # Basic styling
  background black
  border black, :strokewidth => 4    
  
  stack :margin => 10 do    
    # Create tracks
    @tracks = [
      # You might want out your own notes here
      track(:beat => {:note => 34}),
      track(:beat => {:note => 46}),
      track(:beat => {:note => 38}),
      track(:beat => {:note => 36})
      ]
    
    # position-marker / playhead
    stroke yellow; nofill
    @marker = rect(0,0,25,100,4)
  end
  
  # Main loop / Tick
  @loop = animate @tempo do |i|
    pos = i % 16  # on which tick are we
    @marker.left = pos*25 # One beat-square is 25px # FIXME DRY 25
    @tracks.each do |track|      
      beat = track.beats[pos] # getting current beat in track
      if beat.selected?
        Thread.new { 
          @midi.play(beat.options[:note],
                    beat.options[:duration],
                    beat.options[:channel]
                    )
           } 
      end
    end
  end
  
  # Keys
  keypress do |key|
    @loop.toggle if key == " "      
  end
  
end