Added option to display range labels

Off by default, this new option adds labels at the ends of the axis
with the range values. A separate printf-style format string can be
specified for these labels. If a tick label overlaps one of the range
labels, it will not be displayed.

Modified TestAxes and its baseline to exercise this new option.

Charts/Core/Testing/Cxx/TestAxes.cxx

@@ -71,6 +71,9 @@ int TestAxes(int , char * [])
   axesVertical[2]->SetNotation(vtkAxis::SCIENTIFIC_NOTATION);
   axesVertical[2]->SetPosition(vtkAxis::LEFT);
   axesVertical[2]->SetPrecision(0);
+  axesVertical[2]->SetRange(3.2, 97.0);
+  axesVertical[2]->SetRangeLabelsVisible(true);
+  axesVertical[2]->SetRangeLabelFormat("%3.1f");
 
   axesVertical[3]->SetTitle("Custom vertical labels");
   axesVertical[3]->SetCustomTickPositions(positions.GetPointer(),

Charts/Core/Testing/Data/Baseline/TestAxes.png.md5

-0c6a7c321132b435347b4951531f56ee
+e41caf81f47d28338077cf85a75c8075

Charts/Core/vtkAxis.h

@@ -272,6 +272,11 @@ public:
   vtkSetMacro(LabelsVisible, bool);
   vtkGetMacro(LabelsVisible, bool);
 
+  // Description:
+  // Get/set whether the labels for the range should be visible.
+  vtkSetMacro(RangeLabelsVisible, bool);
+  vtkGetMacro(RangeLabelsVisible, bool);
+
   // Description:
   // Get/set whether the tick marks should be visible.
   vtkSetMacro(TicksVisible, bool);
@@ -301,7 +306,14 @@ public:
   // Get/Set the printf-style format string used when TickLabelAlgorithm is
   // TICK_SIMPLE and Notation is PRINTF_NOTATION. The default is "%g".
   virtual void SetLabelFormat(const std::string &fmt);
-  vtkGetMacro(LabelFormat, std::string)
+  vtkGetMacro(LabelFormat, std::string);
+
+  // Description:
+  // Get/Set the printf-style format string used for range labels.
+  // This format is always used regardless of TickLabelAlgorithm and
+  // Notation. Default is "%g".
+  vtkSetMacro(RangeLabelFormat, std::string);
+  vtkGetMacro(RangeLabelFormat, std::string);
 
   // Description:
   // Get/set the numerical notation, standard, scientific, fixed, or a
@@ -440,6 +452,10 @@ protected:
 
   void GenerateLabelFormat(int notation, double n);
 
+  // Description:
+  // Generate label using a printf-style format string.
+  vtkStdString GenerateSprintfLabel(double value, const std::string & format);
+
   // Description:
   // Calculate the next "nicest" numbers above and below the current minimum.
   // \return the "nice" spacing of the numbers.
@@ -508,11 +524,13 @@ protected:
   bool LogScaleActive; // *Is* the axis using a log scale?
   bool GridVisible;    // Whether the grid for the axis should be drawn
   bool LabelsVisible;  // Should the axis labels be visible
+  bool RangeLabelsVisible; // Should range labels be visible?
   bool TicksVisible;   // Should the tick marks be visible.
   bool AxisVisible;    // Should the axis line be visible.
   int Precision;       // Numerical precision to use, defaults to 2.
   int Notation;        // The notation to use (standard, scientific, mixed)
   std::string LabelFormat; // The printf-style format string used for labels.
+  std::string RangeLabelFormat; // The printf-style format string used for range labels.
   int Behavior;        // The behaviour of the axis (auto, fixed, custom).
   float MaxLabel[2];   // The widest/tallest axis label.
   bool TitleAppended;  // Track if the title is updated when the label formats
@@ -577,6 +595,7 @@ private:
   // Description:
   // Return true if the value is in range, false otherwise.
   bool InRange(double value);
+
 //ETX
 };