A preference governs where the pinned head goes, not always exact center

src/Project.cpp

@@ -169,6 +169,7 @@ scroll information.  It also has some status flags.
 #include "commands/CommandContext.h"
 
 #include "prefs/QualityPrefs.h"
+#include "prefs/TracksPrefs.h"
 
 #include "../images/AudacityLogoAlpha.xpm"
 
@@ -6287,7 +6288,8 @@ void AudacityProject::PlaybackScroller::OnTimer(wxCommandEvent &event)
       trackPanel->Refresh(false);
    }
    else if (mMode != Mode::Off) {
-      // Pan the view, so that we center the play indicator.
+      // Pan the view, so that we put the play indicator at some fixed
+      // fraction of the window width.
 
       ViewInfo &viewInfo = mProject->GetViewInfo();
       TrackPanel *const trackPanel = mProject->GetTrackPanel();
@@ -6301,7 +6303,9 @@ void AudacityProject::PlaybackScroller::OnTimer(wxCommandEvent &event)
             wxASSERT(false);
             /* fallthru */
          case Mode::Pinned:
-            deltaX = posX - width / 2;    break;
+            deltaX =
+               posX - width * TracksPrefs::GetPinnedHeadPositionPreference();
+            break;
          case Mode::Right:
             deltaX = posX - width;        break;
       }

src/prefs/TracksPrefs.cpp

@@ -42,6 +42,16 @@ namespace {
    {
       return false;
    }
+   
+   const wxChar *PinnedHeadPositionPreferenceKey()
+   {
+      return wxT("/AudioIO/PinnedHeadPosition");
+   }
+
+   double PinnedHeadPositionPreferenceDefault()
+   {
+      return 0.5;
+   }
 }
 
 
@@ -324,6 +334,21 @@ void TracksPrefs::SetPinnedHeadPreference(bool value, bool flush)
       gPrefs->Flush();
 }
 
+double TracksPrefs::GetPinnedHeadPositionPreference()
+{
+   auto value = gPrefs->ReadDouble(
+      PinnedHeadPositionPreferenceKey(),
+      PinnedHeadPositionPreferenceDefault());
+   return std::max(0.0, std::min(1.0, value));
+}
+
+void TracksPrefs::SetPinnedHeadPositionPreference(double value, bool flush)
+{
+   gPrefs->Write(PinnedHeadPositionPreferenceKey(), value);
+   if(flush)
+      gPrefs->Flush();
+}
+
 wxString TracksPrefs::GetDefaultAudioTrackNamePreference()
 {
    const auto name =

src/prefs/TracksPrefs.h

@@ -34,7 +34,10 @@ class TracksPrefs final : public PrefsPanel
 
    static bool GetPinnedHeadPreference();
    static void SetPinnedHeadPreference(bool value, bool flush = false);
-
+   
+   static double GetPinnedHeadPositionPreference();
+   static void SetPinnedHeadPositionPreference(double value, bool flush = false);
+   
    static wxString GetDefaultAudioTrackNamePreference();
 
    static WaveTrack::WaveTrackDisplay ViewModeChoice();

src/tracks/ui/PlayIndicatorOverlay.cpp

@@ -162,23 +162,25 @@ void PlayIndicatorOverlay::OnTimer(wxCommandEvent &event)
       mProject->TP_DisplaySelection();
 
       // BG: Scroll screen if option is set
-      // msmeyer: But only if not playing looped or in one-second mode
+      if( viewInfo.bUpdateTrackIndicator &&
-      // PRL: and not scrolling with play/record head fixed right
+          playPos >= 0 && !onScreen ) {
-      if (viewInfo.bUpdateTrackIndicator &&
+         // msmeyer: But only if not playing looped or in one-second mode
-          mProject->mLastPlayMode != PlayMode::loopedPlay &&
+         // PRL: and not scrolling with play/record head fixed
-          mProject->mLastPlayMode != PlayMode::oneSecondPlay &&
+         using Mode = AudacityProject::PlaybackScroller::Mode;
-          mProject->GetPlaybackScroller().GetMode() !=
+         const Mode mode = mProject->GetPlaybackScroller().GetMode();
-             AudacityProject::PlaybackScroller::Mode::Right &&
+         const bool pinned = ( mode == Mode::Pinned || mode == Mode::Right );
-         playPos >= 0 &&
+         if (!pinned &&
-         !onScreen &&
+             mProject->mLastPlayMode != PlayMode::loopedPlay &&
-         !gAudioIO->IsPaused())
+             mProject->mLastPlayMode != PlayMode::oneSecondPlay &&
-      {
+             !gAudioIO->IsPaused())
-         mProject->TP_ScrollWindow(playPos);
+         {
-         // Might yet be off screen, check it
+            mProject->TP_ScrollWindow(playPos);
-         onScreen = playPos >= 0.0 &&
+            // Might yet be off screen, check it
+            onScreen = playPos >= 0.0 &&
             between_incexc(viewInfo.h,
                            playPos,
                            mProject->GetScreenEndTime());
+         }
       }
 
       // Always update scrollbars even if not scrolling the window. This is

src/tracks/ui/Scrubbing.cpp

@@ -68,8 +68,10 @@ namespace {
       // with the time at the midline of the screen mapping to 0,
       // and the extremes to the maximum scrub speed.
 
-      // Width of visible track area, in time terms:
+      auto partScreen = screen * TracksPrefs::GetPinnedHeadPositionPreference();
-      const double origin = viewInfo.h + screen / 2.0;
+      const double origin = viewInfo.h + partScreen;
+      if (timeAtMouse >= origin)
+         partScreen = screen - partScreen;
 
       // There are various snapping zones that are this fraction of screen:
       const double snap = 0.05;
@@ -77,8 +79,9 @@ namespace {
       // By shrinking denom a bit, we make margins left and right
       // that snap to maximum and negative maximum speeds.
       const double factor = 1.0 - (snap * 2);
-      const double denom = factor * screen / 2.0;
+      const double denom = factor * partScreen;
-      double fraction = std::min(1.0, fabs(timeAtMouse - origin) / denom);
+      double fraction = (denom <= 0.0) ? 0.0 :
+         std::min(1.0, fabs(timeAtMouse - origin) / denom);
 
       // Snap to 1.0 and -1.0
       const double unity = 1.0 / maxScrubSpeed;
@@ -115,14 +118,16 @@ namespace {
       const double extreme = std::max(1.0, maxScrubSpeed * ARBITRARY_MULTIPLIER);
 
       // Width of visible track area, in time terms:
-      const double halfScreen = screen / 2.0;
+      auto partScreen = screen * TracksPrefs::GetPinnedHeadPositionPreference();
-      const double origin = viewInfo.h + halfScreen;
+      const double origin = viewInfo.h + partScreen;
+      if (timeAtMouse >= origin)
+         partScreen = screen - partScreen;
 
       // The snapping zone is this fraction of screen, on each side of the
       // center line:
       const double snap = 0.05;
-      const double fraction =
+      const double fraction = (partScreen <= 0.0) ? 0.0 :
-         std::max(snap, std::min(1.0, fabs(timeAtMouse - origin) / halfScreen));
+         std::max(snap, std::min(1.0, fabs(timeAtMouse - origin) / partScreen));
 
       double result = 1.0 + ((fraction - snap) / (1.0 - snap)) * (extreme - 1.0);
       if (timeAtMouse < origin)
@@ -343,7 +348,9 @@ bool Scrubber::MaybeStartScrubbing(wxCoord xx)
             if (mDragging && mSmoothScrollingScrub) {
                auto delta = time0 - time1;
                time0 = std::max(0.0, std::min(maxTime,
-                  (viewInfo.h + mProject->GetScreenEndTime()) / 2
+                  viewInfo.h +
+                     (mProject->GetScreenEndTime() - viewInfo.h)
+                        * TracksPrefs::GetPinnedHeadPositionPreference()
                ));
                time1 = time0 + delta;
             }