Method ClearAndAddCutLine

libraries/lib-wave-track/WaveClip.cpp:1415–1477

! @excsafety{Weak} -- This WaveClip remains destructible in case of AudacityException. But some cutlines may be deleted */

-- This WaveClip remains destructible in case of AudacityException.
But some cutlines may be deleted */
void WaveClip::ClearAndAddCutLine(double t0, double t1)
{
   StrongInvariantScope scope{ *this };
   if (t0 > GetPlayEndTime() || t1 < GetPlayStartTime() || CountSamples(t0, t1) == 0)
      return; // no samples to remove

   Transaction transaction{ *this };

   const double clip_t0 = std::max( t0, GetPlayStartTime() );
   const double clip_t1 = std::min( t1, GetPlayEndTime() );

   auto newClip = std::make_shared<WaveClip>(
      *this, GetFactory(), true, clip_t0, clip_t1);
   if(t1 < GetPlayEndTime())
   {
      newClip->ClearSequence(t1, newClip->GetSequenceEndTime())
         .Commit();
      newClip->SetTrimRight(.0);
   }
   if(t0 > GetPlayStartTime())
   {
      newClip->ClearSequence(newClip->GetSequenceStartTime(), t0)
         .Commit();
      newClip->SetTrimLeft(.0);
   }

   newClip->SetSequenceStartTime( clip_t0 - GetSequenceStartTime() );

   // Remove cutlines from this clip that were in the selection, shift
   // left those that were after the selection
   // May DELETE as we iterate, so don't use range-for
   for (auto it = mCutLines.begin(); it != mCutLines.end();)
   {
      WaveClip* clip = it->get();
      double cutlinePosition = GetSequenceStartTime() + clip->GetSequenceStartTime();
      if (cutlinePosition >= t0 && cutlinePosition <= t1)
         it = mCutLines.erase(it);
      else
      {
         if (cutlinePosition >= t1)
         {
            clip->ShiftBy(clip_t0 - clip_t1);
         }
         ++it;
      }
   }

   // Clear actual audio data
   auto s0 = TimeToSequenceSamples(t0);
   auto s1 = TimeToSequenceSamples(t1);

   // use Weak-guarantee
   for (auto &pSequence : mSequences)
      pSequence->Delete(s0, s1-s0);

   // Collapse envelope
   auto sampleTime = 1.0 / GetRate();
   GetEnvelope().CollapseRegion( t0, t1, sampleTime );