libraries/lib-builtin-effects/Generator.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  Generator.cpp
 
  Effects that generate audio can derive from Generator.
 
  Dominic Mazzoni
  Vaughan Johnson
 
**********************************************************************/
 
#include "Generator.h"
#include "EffectOutputTracks.h"
 
#include "BasicUI.h"
#include "Project.h"
#include "Prefs.h"
#include "SyncLock.h"
#include "ViewInfo.h"
#include "WaveTrack.h"
 
#include "TimeWarper.h"
 
bool Generator::Process(EffectInstance &, EffectSettings &settings)
{
   const auto duration = settings.extra.GetDuration();
 
   // Set up mOutputTracks.
   // This effect needs all for sync-lock grouping.
   EffectOutputTracks outputs { *mTracks, GetType(), { { mT0, mT1 } }, true };
 
   // Iterate over the tracks
   bool bGoodResult = true;
   int ntrack = 0;
 
   outputs.Get().Any().VisitWhile(bGoodResult,
      [&](auto &&fallthrough){ return [&](WaveTrack &track) {
         if (!track.GetSelected())
            return fallthrough();
         bool editClipCanMove = GetEditClipsCanMove();
 
         //if we can't move clips, and we're generating into an empty space,
         //make sure there's room.
         if (!editClipCanMove &&
             track.IsEmpty(mT0, mT1 + 1.0 / track.GetRate()) &&
             !track.IsEmpty(mT0,
               mT0 + duration - (mT1 - mT0) - 1.0 / track.GetRate()))
         {
            using namespace BasicUI;
            ShowMessageBox(
               XO("There is not enough room available to generate the audio"),
               MessageBoxOptions {}.IconStyle(Icon::Error));
            bGoodResult = false;
            return;
         }
 
         if (duration > 0.0) {
            // Create a temporary track
            auto copy = track.EmptyCopy();
            // Fill with data
            if (!GenerateTrack(settings, *copy))
               bGoodResult = false;
            if (bGoodResult) {
               copy->Flush();
               PasteTimeWarper warper{ mT1, mT0 + duration };
               auto pProject = FindProject();
               const auto &selectedRegion =
                  ViewInfo::Get(*pProject).selectedRegion;
               // According to https://manual.audacityteam.org/man/silence.html,
               // generating silence with an audio selection should behave like
               // the "Silence Audio" command, which doesn't affect track clip
               // boundaries.
               constexpr auto preserve = true;
               constexpr auto merge = true;
               track.ClearAndPaste(
                  selectedRegion.t0(), selectedRegion.t1(), *copy, preserve,
                  merge, &warper);
            }
            else
               return;
         }
         else
            // If the duration is zero, there's no need to actually
            // generate anything
            track.Clear(mT0, mT1);
 
         ntrack++;
      }; },
      [&](Track &t) {
         if (SyncLock::IsSyncLockSelected(t))
            t.SyncLockAdjust(mT1, mT0 + duration);
      }
   );
 
   if (bGoodResult) {
      outputs.Commit();
      mT1 = mT0 + duration; // Update selection.
   }
 
   return bGoodResult;
}