Method MoveSnappingFreqSelection

src/tracks/ui/SelectHandle.cpp:1405–1454

}

void SelectHandle::MoveSnappingFreqSelection(
   AudacityProject *pProject, ViewInfo &viewInfo, int mouseYCoordinate,
   int trackTopEdge,
   int trackHeight, ChannelView &channelView, Track *const pTrack)
{
   if (pTrack &&
      pTrack->GetSelected() &&
      isSpectralSelectionView(channelView)) {
         auto pWc = channelView.FindChannel<const WaveChannel>();
         // Spectral selection track is always wave
         assert(pWc);
         auto &wc = *pWc;
      // PRL:
      // What would happen if center snapping selection began in one spectrogram track,
      // then continues inside another?  We do not then recalculate
      // the spectrum (as was done in StartSnappingFreqSelection)
      // but snap according to the peaks in the old track.

      // But if we always supply the original clicked track here that doesn't matter.
      const double rate = wc.GetRate();
      const double frequency =
         PositionToFrequency(wc, false, mouseYCoordinate,
         trackTopEdge, trackHeight);
      const double snappedFrequency =
         mFrequencySnapper->FindPeak(frequency, NULL);
      const double maxRatio = findMaxRatio(snappedFrequency, rate);
      double ratio = 2.0; // An arbitrary octave on each side, at most
      {
         const double f0 = viewInfo.selectedRegion.f0();
         const double f1 = viewInfo.selectedRegion.f1();
         if (f1 >= f0 && f0 >= 0)
            // Preserve already chosen ratio instead
            ratio = sqrt(f1 / f0);
      }
      ratio = std::min(ratio, maxRatio);

      mFreqSelPin = snappedFrequency;
      viewInfo.selectedRegion.setFrequencies(
         snappedFrequency / ratio, snappedFrequency * ratio);

      // A change here would affect what AdjustFreqSelection() does
      // in the prototype version where you switch from moving center to
      // dragging width with a click.  No effect now.
      mFreqSelTrack = pWc;

      // SelectNone();
      // SelectTrack(pTrack, true);
      TrackFocus::Get( *pProject ).Set(pTrack);
   }
}

void SelectHandle::SnapCenterOnce(SpectrumAnalyst &analyst,
    ViewInfo &viewInfo, const WaveChannel &wc, bool up)