Class: MTK::Sequencers::EventBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/mtk/sequencers/event_builder.rb

Overview

A special pattern that takes a list of event properties and/or patterns and emits lists of Events::Events

Constant Summary collapse

DEFAULT_PITCH = 
MTK.Pitch(60)
DEFAULT_DURATION = 
MTK.Duration(1)
DEFAULT_INTENSITY = 
MTK.Intensity(0.75)

Instance Method Summary collapse

Constructor Details

#initialize(patterns, options = {}) ⇒ EventBuilder

Returns a new instance of EventBuilder.



11
12
13
14
15
16
17
18
19
20
 
# File 'lib/mtk/sequencers/event_builder.rb', line 11

def initialize(patterns, options={})
  @patterns = patterns
  @options = options
  @default_pitch     = if options.has_key? :default_pitch     then MTK.Pitch(    options[:default_pitch])     else DEFAULT_PITCH     end
  @default_duration  = if options.has_key? :default_duration  then MTK.Duration( options[:default_duration])  else DEFAULT_DURATION  end
  @default_intensity = if options.has_key? :default_intensity then MTK.Intensity(options[:default_intensity]) else DEFAULT_INTENSITY end
  @channel = options[:channel]
  @max_interval = options.fetch(:max_interval, 127)
  rewind
end

Instance Method Details

#next ⇒ Array

Build a list of events from the next element in each Patterns::Pattern

Returns:

  • (Array) —

    an array of events



24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
 
# File 'lib/mtk/sequencers/event_builder.rb', line 24

def next
  pitches = []
  intensities = []
  duration = nil

  @patterns.each do |pattern|
    pattern_value = pattern.next

    elements = if pattern_value.is_a? Enumerable and not pattern_value.is_a? MTK::Groups::PitchCollection then
      pattern_value
    else
      [pattern_value]
    end

    elements.each do |element|
      return nil if element.nil? or element == :skip

      case element
        when ::MTK::Core::Pitch
          pitches << element
          @previous_pitch = element

        when ::MTK::Core::PitchClass
          pitches += pitches_for_pitch_classes([element], @previous_pitch)
          @previous_pitch = pitches.last

        when ::MTK::Groups::PitchClassSet
          pitches += pitches_for_pitch_classes(element, @previous_pitch)
          @previous_pitch = pitches.last

        when ::MTK::Groups::PitchCollection
          pitches += element.pitches # this must be after the PitchClassSet case, because that is also a PitchCollection
          @previous_pitch = pitches.last

        when ::MTK::Core::Duration
          duration ||= 0
          duration += element

        when ::MTK::Core::Intensity
          intensities << element

        when ::MTK::Core::Interval
          if @previous_pitches
            pitches += @previous_pitches.map{|pitch| pitch + element }
          else
            pitches << (@previous_pitch + element)
          end
          @previous_pitch = pitches.last

        # TODO? String/Symbols for special behaviors like :skip, or :break (something like StopIteration for the current Pattern?)

        else STDERR.puts "#{self.class}#next: Unexpected type '#{element.class}'"
      end

    end
  end

  pitches     << @previous_pitch if pitches.empty?
  duration   ||= @previous_duration.abs

  if intensities.empty?
    intensity = @previous_intensity
  else
    intensity = MTK::Core::Intensity[intensities.map{|i| i.to_f }.inject(:+)/intensities.length] # average the intensities
  end

  # Not using this yet, maybe later...
  # return nil if duration==:skip or intensities.include? :skip or pitches.include? :skip

  constrain_pitch(pitches)

  @previous_pitch = pitches.last   # Consider doing something different, maybe averaging?
  @previous_pitches = pitches.length > 1 ? pitches : nil
  @previous_intensity = intensity
  @previous_duration = duration

  if duration.rest?
    [MTK::Events::Rest.new(duration,@channel)]
  else
    pitches.map{|pitch| MTK::Events::Note.new(pitch,duration,intensity,@channel) }
  end
end

#rewind ⇒ Object

Reset the EventBuilder to its initial state



108
109
110
111
112
113
114
115
116
 
# File 'lib/mtk/sequencers/event_builder.rb', line 108

def rewind
  @previous_pitch     = @default_pitch
  @previous_pitches   = [@default_pitch]
  @previous_intensity = @default_intensity
  @previous_duration  = @default_duration
  @max_pitch = nil
  @min_pitch = nil
  @patterns.each{|pattern| pattern.rewind if pattern.is_a? MTK::Patterns::Pattern }
end