Mixer::WarpOptions constructor for common case

src/AudioIOBase.h

@@ -88,7 +88,7 @@ struct AudioIOStartStreamOptions
 
    AudacityProject *pProject{};
    MeterPanelBase *captureMeter{}, *playbackMeter{};
-   BoundedEnvelope *envelope; // for time warping
+   const BoundedEnvelope *envelope; // for time warping
    std::shared_ptr< AudioIOListener > listener;
    double rate;
    bool playLooped;

src/Mix.cpp

@@ -143,11 +143,10 @@ void MixAndRender(TrackList *tracks, WaveTrackFactory *trackFactory,
       endTime = mixEndTime;
    }
 
-   auto timeTrack = *tracks->Any<TimeTrack>().begin();
    Mixer mixer(waveArray,
       // Throw to abort mix-and-render if read fails:
       true,
-      Mixer::WarpOptions(timeTrack ? timeTrack->GetEnvelope() : nullptr),
+      Mixer::WarpOptions{*tracks},
       startTime, endTime, mono ? 1 : 2, maxBlockLen, false,
       rate, format);
 
@@ -204,6 +203,17 @@ void MixAndRender(TrackList *tracks, WaveTrackFactory *trackFactory,
    }
 }
 
+Mixer::WarpOptions::WarpOptions(const TrackList &list)
+: minSpeed(0.0), maxSpeed(0.0)
+{
+   auto timeTrack = *(list.Any<const TimeTrack>().begin());
+   envelope = timeTrack ? timeTrack->GetEnvelope() : nullptr;
+}
+
+Mixer::WarpOptions::WarpOptions(const BoundedEnvelope *e)
+    : envelope(e), minSpeed(0.0), maxSpeed(0.0)
+ {}
+
 Mixer::WarpOptions::WarpOptions(double min, double max)
    : minSpeed(min), maxSpeed(max)
 {

src/Mix.h

@@ -82,10 +82,13 @@ class AUDACITY_DLL_API Mixer {
     class WarpOptions
     {
     public:
-       explicit WarpOptions(const BoundedEnvelope *e)
-          : envelope(e), minSpeed(0.0), maxSpeed(0.0)
-       {}
+       //! Construct with warp from the TimeTrack if there is one
+       explicit WarpOptions(const TrackList &list);
 
+       //! Construct with an explicit warp
+       explicit WarpOptions(const BoundedEnvelope *e);
+
+       //! Construct with no time warp
        WarpOptions(double min, double max);
 
     private:

src/effects/StereoToMono.cpp

@@ -21,7 +21,6 @@
 
 #include "../Mix.h"
 #include "../Project.h"
-#include "../TimeTrack.h"
 #include "../WaveTrack.h"
 
 const ComponentInterfaceSymbol EffectStereoToMono::Symbol
@@ -162,11 +161,9 @@ bool EffectStereoToMono::ProcessOne(sampleCount & curTime, sampleCount totalTime
    tracks.push_back(left->SharedPointer< const WaveTrack >());
    tracks.push_back(right->SharedPointer< const WaveTrack >());
 
-   auto timeTrack = *(inputTracks()->Any<const TimeTrack>().begin());
-
    Mixer mixer(tracks,
                true,                // Throw to abort mix-and-render if read fails:
-               Mixer::WarpOptions(timeTrack ? timeTrack->GetEnvelope() : nullptr),
+               Mixer::WarpOptions{*inputTracks()},
                start,
                end,
                1,

src/export/Export.cpp

@@ -59,7 +59,6 @@
 #include "../ProjectWindow.h"
 #include "../ShuttleGui.h"
 #include "../Tags.h"
-#include "../TimeTrack.h"
 #include "../WaveTrack.h"
 #include "../widgets/AudacityMessageBox.h"
 #include "../widgets/Warning.h"
@@ -234,13 +233,11 @@ std::unique_ptr<Mixer> ExportPlugin::CreateMixer(const TrackList &tracks,
    for (auto pTrack: range)
       inputTracks.push_back(
          pTrack->SharedPointer< const WaveTrack >() );
-   const auto timeTrack = *tracks.Any<const TimeTrack>().begin();
-   auto envelope = timeTrack ? timeTrack->GetEnvelope() : nullptr;
    // MB: the stop time should not be warped, this was a bug.
    return std::make_unique<Mixer>(inputTracks,
                   // Throw, to stop exporting, if read fails:
                   true,
-                  Mixer::WarpOptions(envelope),
+                  Mixer::WarpOptions{tracks},
                   startTime, stopTime,
                   numOutChannels, outBufferSize, outInterleaved,
                   outRate, outFormat,

src/menus/TrackMenus.cpp

@@ -997,9 +997,7 @@ void OnScoreAlign(const CommandContext &context)
       Mixer mix(
          waveTracks,              // const WaveTrackConstArray &inputTracks
          false, // mayThrow -- is this right?
-         Mixer::WarpOptions{
-            *tracks->Any<const TimeTrack >().begin()
-         }, // const WarpOptions &warpOptions
+         Mixer::WarpOptions{ *tracks },
          0.0,                     // double startTime
          endTime,                 // double stopTime
          2,                       // int numOutChannels