Stem Plot option when displaying samples

Initial commit.

src/TrackArtist.cpp

@@ -273,6 +273,7 @@ TrackArtist::TrackArtist()
 
    mdBrange = ENV_DB_RANGE;
    mShowClipping = false;
+   mSampleDisplay = 0;
    UpdatePrefs();
 
    SetColours();
@@ -1362,15 +1363,8 @@ void TrackArtist::DrawIndividualSamples(wxDC &dc, int leftOffset, const wxRect &
                                   rect.height, dB, true, dBRange, false)));
    }
 
-   // Draw lines
-   for (decltype(slen) s = 0; s < slen - 1; s++) {
-      AColor::Line(dc,
-                   rect.x + xpos[s], rect.y + ypos[s],
-                   rect.x + xpos[s + 1], rect.y + ypos[s + 1]);
-   }
 
-   if (showPoints)
-   {
+   if (showPoints) {
       // Draw points where spacing is enough
       const int tickSize = bigPoints ? 4 : 3;// Bigger ellipses when draggable.
       wxRect pr;
@@ -1387,6 +1381,28 @@ void TrackArtist::DrawIndividualSamples(wxDC &dc, int leftOffset, const wxRect &
       }
    }
 
+   if (showPoints && (mSampleDisplay == (int) WaveTrack::StemPlot)) {
+      // Draw vertical lines
+      int yZero = rect.y +
+                  std::max(-1,
+                     std::min(rect.height,
+                        GetWaveYPos(0.0, zoomMin, zoomMax,
+                                    rect.height, dB, true, dBRange, false)));
+      for (decltype(slen) s = 0; s < slen; s++) {
+         AColor::Line(dc,
+                     rect.x + xpos[s], rect.y + ypos[s],
+                     rect.x + xpos[s], yZero);
+      }
+   }
+   else {
+      // Connect samples with straight lines
+      for (decltype(slen) s = 0; s < slen - 1; s++) {
+         AColor::Line(dc,
+                     rect.x + xpos[s], rect.y + ypos[s],
+                     rect.x + xpos[s + 1], rect.y + ypos[s + 1]);
+      }
+   }
+
    // Draw clipping
    if (clipcnt) {
       dc.SetPen(muted ? muteClippedPen : clippedPen);
@@ -3202,6 +3218,7 @@ void TrackArtist::UpdatePrefs()
 {
    mdBrange = gPrefs->Read(ENV_DB_KEY, mdBrange);
    mShowClipping = gPrefs->Read(wxT("/GUI/ShowClipping"), mShowClipping);
+   gPrefs->Read(wxT("/GUI/SampleView"), &mSampleDisplay, 0);
    SetColours();
 }
 

src/TrackArtist.h

@@ -172,6 +172,7 @@ class AUDACITY_DLL_API TrackArtist {
    // Preference values
    float mdBrange;            // "/GUI/EnvdBRange"
    long mShowClipping;        // "/GUI/ShowClipping"
+   int  mSampleDisplay;       // "/GUI/SampleView"
    bool mbShowTrackNameInWaveform;  // "/GUI/ShowTrackNameInWaveform"
 
    int mInsetLeft;

src/WaveTrack.h

@@ -547,6 +547,13 @@ class AUDACITY_DLL_API WaveTrack final : public PlayableTrack {
       NoDisplay,            // Preview track has no display
    };
 
+   // Only two types of sample display for now, but
+   // others (eg sinc interpolation) may be added later.
+   enum SampleDisplay {
+      LinarInterpolate = 0,
+      StemPlot
+   };
+
    // Read appropriate value from preferences
    static WaveTrackDisplay FindDefaultViewMode();
 

src/prefs/TracksPrefs.cpp

@@ -89,6 +89,15 @@ void TracksPrefs::Populate()
    mViewChoices.Add(_("Spectrogram"));
    mViewCodes.Add(WaveTrack::Spectrum);
 
+
+   // How samples are displayed when zoomed in:
+
+   mSampleDisplayChoice.Add(_("Connect dots"));
+   mSampleDisplayCodes.Add((int) WaveTrack::LinarInterpolate);
+
+   mSampleDisplayChoice.Add(_("Stem plot"));
+   mSampleDisplayCodes.Add((int) WaveTrack::StemPlot);
+
    //------------------------- Main section --------------------
    // Now construct the GUI itself.
    // Use 'eIsCreatingFromPrefs' so that the GUI is
@@ -125,6 +134,13 @@ void TracksPrefs::PopulateOrExchange(ShuttleGui & S)
                      mViewCodes);
          S.SetSizeHints(mViewChoices);
 
+         S.TieChoice(_("Display samples:"),
+                     wxT("/GUI/SampleView"),
+                     0,
+                     mSampleDisplayChoice,
+                     mSampleDisplayCodes);
+         S.SetSizeHints(mSampleDisplayChoice);
+
          S.TieTextBox(_("Default audio track &name:"),
                       wxT("/GUI/TrackNames/DefaultTrackName"),
                       _("Audio Track"),

src/prefs/TracksPrefs.h

@@ -43,6 +43,8 @@ class TracksPrefs final : public PrefsPanel
    wxArrayString mSoloChoices;
    wxArrayInt    mViewCodes;
    wxArrayString mViewChoices;
+   wxArrayInt    mSampleDisplayCodes;
+   wxArrayString mSampleDisplayChoice;
 };
 
 class TracksPrefsFactory final : public PrefsPanelFactory