scale.rb in head_music-0.3.1

- old
+ new

@@ -15,35 +15,18 @@
     @scale_type = HeadMusic::ScaleType.get(scale_type)
   end
 
   def pitches
     @pitches ||= begin
-      pitches = [root_pitch]
-      letters_cycle = HeadMusic::Letter::NAMES
-      letters_cycle = letters_cycle.rotate while letters_cycle.first != root_pitch.letter.to_s
+      letter_cycle = root_pitch.letter_cycle
       semitones_from_root = 0
-      if scale_type.parent
-        parent_scale_pitches = HeadMusic::Scale.get(root_pitch, scale_type.parent_name).pitches
-      end
-      scale_type.intervals.each_with_index do |semitones, i|
-        semitones_from_root += semitones
-        pitch_number = root_pitch.pitch_class.to_i + semitones_from_root
-        if scale_type.intervals.length == 7
-          current_letter = letters_cycle[(i + 1) % 7]
-        elsif scale_type.intervals.length < 7 && scale_type.parent
-          current_letter = parent_scale_pitches.detect { |parent_scale_pitches|
-            parent_scale_pitches.pitch_class == (root_pitch + semitones_from_root).to_i % 12
-          }.letter
-        elsif root_pitch.flat?
-          current_letter = HeadMusic::PitchClass::FLAT_SPELLINGS[pitch_number % 12]
-        else
-          current_letter = HeadMusic::PitchClass::SHARP_SPELLINGS[pitch_number % 12]
+      [root_pitch].tap do |pitches|
+        scale_type.intervals.each_with_index do |semitones, i|
+          semitones_from_root += semitones
+          pitches << pitch_for_step(i+1, semitones_from_root)
         end
-        pitch = HeadMusic::Pitch.from_number_and_letter(pitch_number, current_letter)
-        pitches << pitch
       end
-      pitches
     end
   end
 
   def pitch_names
     pitches.map(&:spelling).map(&:to_s)
@@ -62,7 +45,46 @@
         spellings << HeadMusic::Spelling.get([letter, accidental].join)
       end
       letter_index = (letter_index + 1) % 7
     end
     spellings
+  end
+
+  def letter_cycle
+    @letter_cycle ||= root_pitch.letter_cycle
+  end
+
+  def root_pitch_class
+    @root_pitch_class ||= root_pitch.pitch_class
+  end
+
+  private
+
+  def parent_scale_pitches
+    HeadMusic::Scale.get(root_pitch, scale_type.parent_name).pitches if scale_type.parent
+  end
+
+  def parent_scale_pitch_for(semitones_from_root)
+    parent_scale_pitches.detect { |parent_scale_pitch|
+      parent_scale_pitch.pitch_class == (root_pitch + semitones_from_root).to_i % 12
+    }
+  end
+
+  def letter_for_step(step, semitones_from_root)
+    pitch_class_number = (root_pitch.pitch_class.to_i + semitones_from_root) % 12
+    if scale_type.intervals.length == 7
+      letter_cycle[step % 7]
+    elsif scale_type.intervals.length < 7 && parent_scale_pitches
+      parent_scale_pitch_for(semitones_from_root).letter
+    elsif root_pitch.flat?
+      HeadMusic::PitchClass::FLAT_SPELLINGS[pitch_class_number]
+    else
+      HeadMusic::PitchClass::SHARP_SPELLINGS[pitch_class_number]
+    end
+  end
+
+  def pitch_for_step(step, semitones_from_root)
+    pitch_number = root_pitch_class.to_i + semitones_from_root
+    letter = letter_for_step(step, semitones_from_root)
+    HeadMusic::Pitch.from_number_and_letter(pitch_number, letter)
   end
 end