Method Shift

libraries/lib-note-track/NoteTrack.cpp:529–554

Call this function to manipulate the underlying sequence data. This is NOT the function that handles horizontal dragging.

// Call this function to manipulate the underlying sequence data. This is
// NOT the function that handles horizontal dragging.
bool NoteTrack::Shift(double t) // t is always seconds
{
   if (t > 0) {
      auto &seq = GetSeq();
      // insert an even number of measures
      seq.convert_to_beats();
      // get initial tempo
      double tempo = seq.get_tempo(0.0);
      double beats_per_measure = seq.get_bar_len(0.0);
      int m = ROUND(t * tempo / beats_per_measure);
      // need at least 1 measure, so if we rounded down to zero, fix it
      if (m == 0) m = 1;
      // compute NEW tempo so that m measures at NEW tempo take t seconds
      tempo = beats_per_measure * m / t; // in beats per second
      seq.insert_silence(0.0, beats_per_measure * m);
      seq.set_tempo(tempo * 60.0 /* bpm */, 0.0, beats_per_measure * m);
      seq.write("afterShift.gro");
   } else if (t < 0) {
      auto &seq = GetSeq();
      seq.convert_to_seconds();
      seq.clear(0, t, true);
   } else { // offset is zero, no modifications
      return false;
   }
   return true;
}

QuantizedTimeAndBeat NoteTrack::NearestBeatTime( double time ) const
{