Refs #5187: fix non-spectra axis in SliceViewer

for Workspace2D

Code/Mantid/Framework/API/inc/MantidAPI/NumericAxis.h

@@ -64,6 +64,7 @@ class MANTID_API_DLL NumericAxis: public Axis
   std::string label(const std::size_t& index)const;
   /// Create bin boundaries from the point values
   std::vector<double> createBinBoundaries() const;
+  const std::vector<double> & getValues() const;
 private:
   /// Private, undefined copy assignment operator
   const NumericAxis& operator=(const NumericAxis&);

Code/Mantid/Framework/API/src/MatrixWorkspace.cpp

@@ -1584,7 +1584,25 @@ namespace Mantid
     {
       coord_t x = coords[0];
       coord_t y = coords[1];
+
+      // First, find the workspace index
+      NumericAxis * ax1 = dynamic_cast<NumericAxis*>(this->getAxis(1));
+
+      // If a spectra/text axis, just use the Y coord as the workspace index
       size_t wi = size_t(y);
+      if (ax1)
+      {
+        const MantidVec & yVals = ax1->getValues();
+        MantidVec::const_iterator it = std::lower_bound(yVals.begin(), yVals.end(), y);
+        if (it == yVals.end())
+        {
+          // Out of range
+          return std::numeric_limits<double>::quiet_NaN();
+        }
+        // The workspace index is the point in the vector that we found
+        wi = it - yVals.begin();
+      }
+
       if (wi < this->getNumberHistograms())
       {
         const MantidVec & X = this->readX(wi);

Code/Mantid/Framework/API/src/NumericAxis.cpp

@@ -118,5 +118,14 @@ std::vector<double> NumericAxis::createBinBoundaries() const
   return boundaries;
 }
 
+/** Get a const reference to the vector of values in this axis
+ *
+ * @return the values vector
+ */
+const std::vector<double> &  NumericAxis::getValues() const
+{
+  return m_values;
+}
+
 } // namespace API
 } // namespace Mantid