!7

import static x30_pkg.x30_util.VF1;

sclass AudioOutput > DynPrintLog {
  int bufSize = 40960;
  float gain = 1;
  transient playAudioFromSampleMakingFunction_AudioLoop loop;
  transient L<VF1<double[]>> sources = synchroList();
  
  JComponent visualize() {
    ret centerAndSouth(super.visualize(),
      withLabel("Volume (0-200%):", liveSliderZeroToOne(gain/2, voidfunc(float f) { setField(gain := f*2) })));
  }
  
  void start {
    ownTimer(loop = playAudioFromSampleMakingFunction(bufSize, voidfunc(double[] pair) {
      makeSample(pair)
    }));
  }
  
  void makeSample(double[] pair) {
    double l = 0, r = 0;
    for i over sources: { // synchro-safe, garbage-free iteration
      VF1<double[]> source = syncGet(sources, i);
      continue if source == null;
      callF(source, pair);
      l += pair[0];
      r += pair[1];
    }
    pair[0] = l*gain; pair[1] = r*gain;
  }
  
  void addSource(VF1<double[]> source) { sources.add(source); }
  void removeSource(VF1<double[]> source) { sources.remove(source); }
}