Put the scroll-beyond-zero flag in just one place, ViewInfo

src/Menus.cpp

@@ -4955,7 +4955,7 @@ void AudacityProject::OnZoomNormal()
 void AudacityProject::OnZoomFit()
 {
    const double end = mTracks->GetEndTime();
-   const double start = mScrollBeyondZero
+   const double start = mViewInfo.bScrollBeyondZero
       ? std::min(mTracks->GetStartTime(), 0.0)
       : 0;
    const double len = end - start;

src/Project.cpp

@@ -780,7 +780,6 @@ AudacityProject::AudacityProject(wxWindow * parent, wxWindowID id,
      mIsDeleting(false),
      mTracksFitVerticallyZoomed(false),  //lda
      mShowId3Dialog(true),               //lda
-     mScrollBeyondZero(false),
      mLastFocusedWindow(NULL),
      mKeyboardCaptureHandler(NULL),
      mImportXMLTagHandler(NULL),
@@ -1052,9 +1051,6 @@ AudioIOStartStreamOptions AudacityProject::GetDefaultPlayOptions()
 
 void AudacityProject::UpdatePrefsVariables()
 {
-#ifdef EXPERIMENTAL_SCROLLING_LIMITS
-   gPrefs->Read(wxT("/GUI/ScrollBeyondZero"), &mScrollBeyondZero, false);
-#endif
    gPrefs->Read(wxT("/AudioFiles/ShowId3Dialog"), &mShowId3Dialog, true);
    gPrefs->Read(wxT("/AudioFiles/NormalizeOnLoad"),&mNormalizeOnLoad, false);
    gPrefs->Read(wxT("/GUI/AutoScroll"), &mViewInfo.bUpdateTrackIndicator, true);
@@ -1474,7 +1470,7 @@ void AudacityProject::OnScrollRightButton(wxScrollEvent & event)
 
 double AudacityProject::ScrollingLowerBoundTime() const
 {
-   if (!mScrollBeyondZero)
+   if (!mViewInfo.bScrollBeyondZero)
       return 0;
    const double screen = mTrackPanel->GetScreenEndTime() - mViewInfo.h;
    return std::min(mTracks->GetStartTime(), -screen / 2.0);
@@ -1583,7 +1579,7 @@ void AudacityProject::FixScrollbars()
    // may be scrolled to the midline.
    // May add even more to the end, so that you can always scroll the starting time to zero.
    const double lowerBound = ScrollingLowerBoundTime();
-   const double additional = mScrollBeyondZero
+   const double additional = mViewInfo.bScrollBeyondZero
       ? -lowerBound + std::max(halfScreen, screen - LastTime)
       : screen / 4.0;
 
@@ -1921,7 +1917,7 @@ void AudacityProject::OnScroll(wxScrollEvent & WXUNUSED(event))
    }
 
 
-   if (mScrollBeyondZero) {
+   if (mViewInfo.bScrollBeyondZero) {
       enum { SCROLL_PIXEL_TOLERANCE = 10 };
       if (std::abs(mViewInfo.TimeToPosition(0.0, 0
                                    )) < SCROLL_PIXEL_TOLERANCE) {

src/Project.h

@@ -606,8 +606,6 @@ class AUDACITY_DLL_API AudacityProject:  public wxFrame,
    bool mShowId3Dialog; //lda
    bool mEmptyCanBeDirty;
 
-   bool mScrollBeyondZero;
-
    bool mSelectAllOnNone;
 
    bool mIsSyncLocked;

src/TrackPanel.cpp

@@ -888,9 +888,6 @@ void TrackPanel::UpdateVirtualStereoOrder()
 
 void TrackPanel::UpdatePrefs()
 {
-#ifdef EXPERIMENTAL_SCROLLING_LIMITS
-   gPrefs->Read(wxT("/GUI/ScrollBeyondZero"), &mScrollBeyondZero, false);
-#endif
    gPrefs->Read(wxT("/GUI/AutoScroll"), &mViewInfo->bUpdateTrackIndicator,
       true);
    gPrefs->Read(wxT("/GUI/AdjustSelectionEdges"), &mAdjustSelectionEdges,
@@ -7527,7 +7524,7 @@ void TrackPanel::TimerUpdateScrubbing(double playPos)
       const int deltaX = posX - width / 2;
       mViewInfo->h =
          mViewInfo->OffsetTimeByPixels(mViewInfo->h, deltaX, true);
-      if (!mScrollBeyondZero)
+      if (!mViewInfo->bScrollBeyondZero)
          // Can't scroll too far left
          mViewInfo->h = std::max(0.0, mViewInfo->h);
       Refresh(false);

src/TrackPanel.h

@@ -808,7 +808,6 @@ protected:
    enum MouseCaptureEnum mMouseCapture;
    virtual void SetCapturedTrack( Track * t, enum MouseCaptureEnum MouseCapture=IsUncaptured );
 
-   bool mScrollBeyondZero;
    bool mAdjustSelectionEdges;
    bool mSlideUpDownOnly;
    bool mCircularTrackNavigation;

src/ViewInfo.cpp

@@ -9,6 +9,7 @@ Paul Licameli
 **********************************************************************/
 
 #include "ViewInfo.h"
+#include "Experimental.h"
 
 #include <algorithm>
 
@@ -110,7 +111,18 @@ ViewInfo::ViewInfo(double start, double screenDuration, double pixelsPerSecond)
    , sbarScale(1.0)
    , scrollStep(16)
    , bUpdateTrackIndicator(true)
+   , bScrollBeyondZero(false)
 {
+   UpdatePrefs();
+}
+
+void ViewInfo::UpdatePrefs()
+{
+   ZoomInfo::UpdatePrefs();
+#ifdef EXPERIMENTAL_SCROLLING_LIMITS
+   gPrefs->Read(wxT("/GUI/ScrollBeyondZero"), &bScrollBeyondZero, false);
+#endif
+
 }
 
 void ViewInfo::SetBeforeScreenWidth(wxInt64 beforeWidth, wxInt64 screenWidth, double lowerBoundTime)

src/ViewInfo.h

@@ -130,6 +130,8 @@ class AUDACITY_DLL_API ViewInfo
 public:
    ViewInfo(double start, double screenDuration, double pixelsPerSecond);
 
+   void UpdatePrefs();
+
    double GetBeforeScreenWidth() const
    {
       return h * zoom;
@@ -167,6 +169,8 @@ public:
 
    bool bUpdateTrackIndicator;
 
+   bool bScrollBeyondZero;
+
    void WriteXMLAttributes(XMLWriter &xmlFile);
    bool ReadXMLAttribute(const wxChar *attr, const wxChar *value);
 };