Added zoom presets

Please Note:
In ViewInfo.h there is the comment left by Paul:
// There is NO GetZoom()!
// Use TimeToPosition and PositionToTime and OffsetTimeByPixels!

I needed to get the value of the current zoom so that I could use the functions AudacityProject::ZoomInByFactor and AudacityProject::ZoomOutByFactor to handle the change in zoom when a preset zoom is chosen. So I added GetZoom() for this use.

src/Menus.cpp

@@ -696,6 +696,13 @@ void AudacityProject::CreateMenusAndCommands()
       c->AddItem(wxT("ZoomSel"), _("&Zoom to Selection"), FN(OnZoomSel), wxT("Ctrl+E"), TimeSelectedFlag, TimeSelectedFlag);
       c->EndSubMenu();
 
+      c->BeginSubMenu(_("Set One &Pixel to"));
+      c->AddItem(wxT("ZoomOneSecond"), _("&One Second"), FN(OnZoomOneSecond));
+      c->AddItem(wxT("ZoomTenthSecond"), _("&Tenth Second"), FN(OnZoomTenthSecond));
+      c->AddItem(wxT("ZoomHundredthSecond"), _("&Hundredth Second"), FN(OnZoomHundredthSecond));
+      c->AddItem(wxT("ZoomThousandthSecond"), _("Thou&sandth Second"), FN(OnZoomThousandthSecond));
+      c->EndSubMenu();
+
       c->AddSeparator();
       c->BeginSubMenu(_("&Track Size"));
       c->AddItem(wxT("FitInWindow"), _("&Fit to Width"), FN(OnZoomFit), wxT("Ctrl+F"));
@@ -5653,6 +5660,39 @@ void AudacityProject::OnZoomNormal()
    mTrackPanel->Refresh(false);
 }
 
+void AudacityProject::OnZoomOneSecond()
+{
+   OnZoomPreset(1.0);
+}
+
+void AudacityProject::OnZoomTenthSecond()
+{
+   OnZoomPreset(10.0);
+}
+
+void AudacityProject::OnZoomHundredthSecond()
+{
+   OnZoomPreset(100.0);
+}
+
+void AudacityProject::OnZoomThousandthSecond()
+{
+   OnZoomPreset(1000.0);
+}
+
+void AudacityProject::OnZoomPreset(double newZoom)
+{
+   double currentZoom = mViewInfo.GetZoom();
+
+   if (currentZoom != 0.0) {
+      double ratio = newZoom/currentZoom;
+      if (ratio > 1.0 )
+         ZoomInByFactor(ratio);
+      else if (ratio < 1.0)
+         ZoomOutByFactor(ratio);
+   }
+}
+
 void AudacityProject::OnZoomFit()
 {
    const double end = mTracks->GetEndTime();

src/Menus.h

@@ -301,6 +301,11 @@ void OnZoomIn();
 void OnZoomOut();
 // void OnZoomToggle();
 void OnZoomNormal();
+void OnZoomOneSecond();
+void OnZoomTenthSecond();
+void OnZoomHundredthSecond();
+void OnZoomThousandthSecond();
+void OnZoomPreset(double newZoom);
 void OnZoomFit();
 void OnZoomFitV();
 void DoZoomFitV();

src/ViewInfo.h

@@ -86,6 +86,9 @@ public:
 
    // There is NO GetZoom()!
    // Use TimeToPosition and PositionToTime and OffsetTimeByPixels!
+   // DB added GetZoom() - needed for zoom presets.
+
+   double GetZoom() const {return zoom; }
 
    // Limits zoom to certain bounds
    void SetZoom(double pixelsPerSecond);