code: /*
   * Computoser is a music-composition algorithm and a website to present the results
   * Copyright (C) 2012-2014  Bozhidar Bozhanov
   *
   * Computoser is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Affero General Public License as
   * published by the Free Software Foundation, either version 3 of the
   * License, or (at your option) any later version.
   *
   * Computoser is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Affero General Public License for more details.
   *
   * You should have received a copy of the GNU Affero General Public License
   * along with Computoser.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package com.music;
  
  import java.util.Random;
  
  import com.music.model.PartType;
  import com.music.model.prefs.UserPreferences;
  import com.music.util.music.Chance;
  import com.music.util.music.NoteFactory;
  
  import jm.constants.Pitches;
  import jm.music.data.Note;
  import jm.music.data.Part;
  import jm.music.data.Phrase;
  import jm.music.data.Rest;
  import jm.music.data.Score;
  
  public class EffectsGenerator implements ScoreManipulator {
      private Random random = new Random();
  
      @Override
      public void handleScore(Score score, ScoreContext ctx, UserPreferences prefs) {
          Part effectsPart = ctx.getParts().get(PartType.EFFECTS);
          if (effectsPart == null) {
              return;
          }
          Phrase phrase = new Phrase();
          int restPercentage = Chance.test(65) ? 75 : 15; //sporadic vs regular
          for (int i = 0; i < ctx.getMeasures(); i++) {
              handleEffects(ctx, phrase, restPercentage);
          }
          effectsPart.add(phrase);
      }
  
  
      private void handleEffects(ScoreContext ctx, Phrase phrase, int restPercentages) {
          if (Chance.test(restPercentages)) {
              phrase.addRest(new Rest(ctx.getNormalizedMeasureSize()));
          } else {
              int pitch = getRandomPitch(ctx);
              double effectLength = random.nextDouble() * ctx.getNormalizedMeasureSize();
              effectLength = Math.min(effectLength, ctx.getNormalizedMeasureSize());
              Note note = NoteFactory.createNote(pitch, effectLength);
              phrase.add(note);
              double lastRest = ctx.getNormalizedMeasureSize() - effectLength;
              if (lastRest > 0) {
                  phrase.add(new Rest(lastRest));
              }
          }
      }
  
      private int getRandomPitch(ScoreContext ctx) {
          int pitch = Pitches.C4
                  + ctx.getKeyNote()
                  + ctx.getScale().getDefinition()[random.nextInt(ctx.getScale().getDefinition().length)];
          return pitch;
      }
  }
  