C++ MidiEvent::ShiftNote方法代码示例

void PlayingState::Listen() {
  if (!m_state.midi_in)
    return;

  while (m_state.midi_in->KeepReading()) {

    microseconds_t cur_time = m_state.midi->GetSongPositionInMicroseconds();
    MidiEvent ev = m_state.midi_in->Read();
    if (m_state.midi_in->ShouldReconnect())
    {
        m_state.midi_in->Reconnect();
        m_state.midi_out->Reconnect();
        continue;
    }


    // Just eat input if we're paused
    if (m_paused)
      continue;

    // We're only interested in NoteOn and NoteOff
    if (ev.Type() != MidiEventType_NoteOn && ev.Type() != MidiEventType_NoteOff)
      continue;

    // Octave Sliding
    ev.ShiftNote(m_note_offset);

    int note_number = ev.NoteNumber();
    string note_name = MidiEvent::NoteName(note_number);

    // On key release we have to look for existing "active" notes and turn them off.
    if (ev.Type() == MidiEventType_NoteOff || ev.NoteVelocity() == 0) {

      // NOTE: This assumes mono-channel input.  If they're piping an entire MIDI file
      //       (or even the *same* MIDI file) through another source, we could get the
      //       same NoteId on different channels -- and this code would start behaving
      //       incorrectly.
      for (ActiveNoteSet::iterator i = m_active_notes.begin(); i != m_active_notes.end(); ++i) {
        if (ev.NoteNumber() != i->note_id)
          continue;

        // Play it on the correct channel to turn the note we started
        // previously, off.
        ev.SetChannel(i->channel);
        if (m_state.midi_out)
          m_state.midi_out->Write(ev);

        m_active_notes.erase(i);
        break;
      }

      // User releases the key
      // If we delete this line, than all pressed keys will be gray until
      // it is unpressed automatically
      m_keyboard->SetKeyActive(note_name, false, Track::FlatGray);
      userPressedKey(note_number, false);
      continue;
    }

    TranslatedNoteSet::iterator closest_match = m_notes.end();
    for (TranslatedNoteSet::iterator i = m_notes.begin(); i != m_notes.end(); ++i) {

      const microseconds_t window_start = i->start - (KeyboardDisplay::NoteWindowLength / 2);
      const microseconds_t window_end = i->start + (KeyboardDisplay::NoteWindowLength / 2);

      // As soon as we start processing notes that couldn't possibly
      // have been played yet, we're done.
      if (window_start > cur_time)
        break;

      if (i->state != UserPlayable)
        continue;

      if (window_end > cur_time && i->note_id == ev.NoteNumber()) {

        if (closest_match == m_notes.end()) {
          closest_match = i;
          continue;
        }

        microseconds_t this_distance = cur_time - i->start;
        if (i->start > cur_time)
          this_distance = i->start - cur_time;

        microseconds_t known_best = cur_time - closest_match->start;
        if (closest_match->start > cur_time)
          known_best = closest_match->start - cur_time;

        if (this_distance < known_best)
          closest_match = i;
      }
    }

    Track::TrackColor note_color = Track::FlatGray;

    if (closest_match != m_notes.end()) {
      note_color = m_state.track_properties[closest_match->track_id].color;

      // "Open" this note so we can catch the close later and turn off
      // the note.
//.........这里部分代码省略.........