Stubs needed to eliminate remaining direct uses of ViewInfo::zoom ...

... and anticipate a problems fisheye will introduce with time ruler display
and horizontal scrolling past zero.

Will be used in waveform and spectrogram drawing, and in hit-test for sample
editing.  Those things will no longer make the assumption of uniform zoom
level across the width of the screen, though that does remain true without the
rest of the fisheye project.

src/ViewInfo.cpp

@@ -37,7 +37,8 @@ ZoomInfo::~ZoomInfo()
 /// the track as an additional parameter.
 double ZoomInfo::PositionToTime(wxInt64 position,
    wxInt64 origin
-   ) const
+   , bool // ignoreFisheye
+) const
 {
    return h + (position - origin) / zoom;
 }
@@ -46,7 +47,8 @@ double ZoomInfo::PositionToTime(wxInt64 position,
 /// STM: Converts a project time to screen x position.
 wxInt64 ZoomInfo::TimeToPosition(double projectTime,
    wxInt64 origin
-   ) const
+   , bool // ignoreFisheye
+) const
 {
    return floor(0.5 +
       zoom * (projectTime - h) + origin
@@ -73,6 +75,23 @@ void ZoomInfo::ZoomBy(double multiplier)
    SetZoom(zoom * multiplier);
 }
 
+void ZoomInfo::FindIntervals
+   (double /*rate*/, Intervals &results, wxInt64 origin) const
+{
+   results.clear();
+   results.reserve(2);
+
+   const wxInt64 rightmost(origin + (0.5 + screen * zoom));
+   wxASSERT(origin <= rightmost);
+   {
+      results.push_back(Interval(origin, zoom, false));
+   }
+
+   if (origin < rightmost)
+      results.push_back(Interval(rightmost, 0, false));
+   wxASSERT(!results.empty() && results[0].position == origin);
+}
+
 ViewInfo::ViewInfo(double start, double screenDuration, double pixelsPerSecond)
    : ZoomInfo(start, screenDuration, pixelsPerSecond)
    , selectedRegion()

src/ViewInfo.h

@@ -11,6 +11,7 @@
 #ifndef __AUDACITY_VIEWINFO__
 #define __AUDACITY_VIEWINFO__
 
+#include <vector>
 #include "SelectedRegion.h"
 
 
@@ -41,6 +42,7 @@ public:
    // origin specifies the pixel corresponding to time h
    double PositionToTime(wxInt64 position,
       wxInt64 origin = 0
+      , bool ignoreFisheye = false
       ) const;
 
    // do NOT use this once to convert a duration to a pixel width!
@@ -49,6 +51,7 @@ public:
    // origin specifies the pixel corresponding to time h
    wxInt64 TimeToPosition(double time,
       wxInt64 origin = 0
+      , bool ignoreFisheye = false
       ) const;
 
    double OffsetTimeByPixels(double time, wxInt64 offset) const
@@ -78,6 +81,46 @@ public:
    // Limits zoom to certain bounds
    // multipliers above 1.0 zoom in, below out
    void ZoomBy(double multiplier);
+
+   struct Interval {
+      const wxInt64 position; const double averageZoom; const bool inFisheye;
+      Interval(wxInt64 p, double z, bool i)
+         : position(p), averageZoom(z), inFisheye(i) {}
+   };
+   typedef std::vector<Interval> Intervals;
+
+   // Find an increasing sequence of pixel positions.  Each is the start
+   // of an interval, or is the end position.
+   // Each of the disjoint intervals should be drawn
+   // separately.
+   // It is guaranteed that there is at least one entry and the position of the
+   // first entry equals origin.
+   // @param origin specifies the pixel position corresponding to time ViewInfo::h.
+   void FindIntervals
+      (double rate, Intervals &results, wxInt64 origin = 0) const;
+
+   enum FisheyeState {
+      HIDDEN,
+      PINNED,
+
+      NUM_STATES,
+   };
+   FisheyeState GetFisheyeState() const
+   { return HIDDEN; } // stub
+
+   // Return true if the mouse position is anywhere in the fisheye
+   // origin specifies the pixel corresponding to time h
+   bool InFisheye(wxInt64 position, wxInt64 origin = 0) const
+   {origin; return false;} // stub
+
+   // These accessors ignore the fisheye hiding state.
+   // Inclusive:
+   wxInt64 GetFisheyeLeftBoundary(wxInt64 origin = 0) const
+   {origin; return 0;} // stub
+   // Exclusive:
+   wxInt64 GetFisheyeRightBoundary(wxInt64 origin = 0) const
+   {origin; return 0;} // stub
+
 };
 
 class AUDACITY_DLL_API ViewInfo