Class: Chords::Fingering

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/chords/fingering.rb

Constant Summary collapse

DEFAULT_MAX_FRET_DISTANCE = 
3

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(fretboard, positions = nil) ⇒ Fingering

Returns a new instance of Fingering.



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# File 'lib/chords/fingering.rb', line 12

def initialize(fretboard, positions=nil)
  @fretboard = fretboard
  @positions = positions || ([nil] * @fretboard.open_notes.size)
end

Class Method Details

.find_variations(fretboard, chord, opts = {}) ⇒ Object 



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# File 'lib/chords/fingering.rb', line 17

def self.find_variations(fretboard, chord, opts={})
  fingering = Fingering.new(fretboard)
  fingerings = fingering.expand(chord.notes.first)
  
  chord.notes[1..-1].each do |note|
    fingerings = fingerings.map{|f| f.expand(note, opts)}.flatten(1)
  end
  
  (opts[:duplicates] || 0).times do
    fingerings = fingerings.map{|f| f.add_duplicate(opts)}.flatten(1).uniq
  end
  
  fingerings
end

Instance Method Details

#add_duplicate(opts = {}) ⇒ Object

returns variations of this fingering with one duplicate note added



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# File 'lib/chords/fingering.rb', line 55

def add_duplicate(opts={})
  return [] if unused_strings < 1
  max_fret_dist = opts[:max_fret_distance] || DEFAULT_MAX_FRET_DISTANCE
  
  fingerings = []
  
  @positions.each_with_index do |pos, i|
    next unless pos.nil?
    
    each_note do |note|
      new_note_positions(note, i, max_fret_dist).each do |pos|
        new_positions = @positions.dup
        new_positions[i] = pos
        fingerings << Fingering.new(@fretboard, new_positions)
      end
    end
  end
  
  fingerings
end

#each_note ⇒ Object 



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# File 'lib/chords/fingering.rb', line 76

def each_note
  @positions.each_with_index do |pos, i|
    yield((@fretboard.open_notes[i] + pos).class) unless pos.nil?
  end
end

#eql?(other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chords/fingering.rb', line 82

def eql?(other)
  self.hash == other.hash
end

#expand(note, opts = {}) ⇒ Object

Returns all fingering variations of this fingering expanded with note. Expanded note wil be on a higher string than existing notes. It will also be the highest note.



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# File 'lib/chords/fingering.rb', line 36

def expand(note, opts={})
  max_fret_dist = opts[:max_fret_distance] || DEFAULT_MAX_FRET_DISTANCE
  
  fingerings = []
  
  ((highest_used_string+1)..(@positions.size-1)).each do |str_i|
    new_note_positions(note, str_i, max_fret_dist).each do |pos|
      if (@fretboard.open_notes[str_i] + pos) > highest_note
        new_positions = @positions.dup
        new_positions[str_i] = pos
        fingerings << Fingering.new(@fretboard, new_positions)
      end
    end
  end
  
  fingerings
end

#fid ⇒ Object

Fingering id, a unique identifier for fretboard/fingering combo. Actually, fid is not unique if max_fret_distance >= 9, as positions [0,10,0,0,1,0] and [0,1,0,0,0,10] produce the same fid (if the tuning is the same). However, max_fret_distance of 9 or greater is not realistic.



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# File 'lib/chords/fingering.rb', line 96

def fid
  @fretboard.open_notes.map{|n| n.class.title}.to_s + 
    @positions.map{|pos| pos.nil? ? 'x' : pos}.to_s
end

#hash ⇒ Object 



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# File 'lib/chords/fingering.rb', line 86

def hash
  @positions.hash
end

#max_fret_distance ⇒ Object 



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# File 'lib/chords/fingering.rb', line 113

def max_fret_distance
  max_fret_dist = 0
  tmp = @positions.select{|pos| !pos.nil? and pos > 0}
  max_fret_dist = tmp.max - tmp.min unless tmp.empty?
  max_fret_dist
end

#relative(max_fret_dist) ⇒ Object

return an array of relative positions



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# File 'lib/chords/fingering.rb', line 102

def relative(max_fret_dist)
  not_open = @positions.select{|p| !p.nil? and p > 0}
  
  if not_open.max <= (max_fret_dist + 1)
    @positions
  else
    diff = (not_open.min - 1)
    @positions.map{|p| (p.nil? or p == 0) ? p : p - diff}
  end
end