[CHANGE] - now multiple histograms can be cached in WDataSetSingle once they have been requested.

src/dataHandler/WDataSetScalar.cpp

@@ -43,9 +43,6 @@ WDataSetScalar::WDataSetScalar( boost::shared_ptr< WValueSetBase > newValueSet,
     WAssert( newGrid, "No grid given." );
     WAssert( newValueSet->size() == newGrid->size(), "Number of values unequal number of positions in grid." );
     WAssert( newValueSet->order() == 0, "The value set does not contain scalars." );
-
-    // the histogram gets calculated on demand
-    m_histogram = boost::shared_ptr< WValueSetHistogram >();
 }
 
 WDataSetScalar::WDataSetScalar()
@@ -138,16 +135,18 @@ double WDataSetScalar::getValueAt( int x, int y, int z ) const
     return WDataSetSingle::getValueAt( id );
 }
 
-boost::shared_ptr< const WValueSetHistogram > WDataSetScalar::getHistogram()
+boost::shared_ptr< const WValueSetHistogram > WDataSetScalar::getHistogram( size_t buckets )
 {
-    if ( m_histogram )
+    boost::lock_guard<boost::mutex> lock( m_histogramLock );
+
+    if ( m_histograms.count( buckets ) != 0 )
     {
-        return m_histogram;
+        return m_histograms[ buckets ];
     }
 
-    boost::lock_guard<boost::mutex> lock( m_histogramLock );
-    m_histogram = boost::shared_ptr< WValueSetHistogram >( new WValueSetHistogram( m_valueSet ) );
+    // create if not yet existing
+    m_histograms[ buckets ] = boost::shared_ptr< WValueSetHistogram >( new WValueSetHistogram( m_valueSet, buckets ) );
 
-    return m_histogram;
+    return m_histograms[ buckets ];
 }
 

src/dataHandler/WDataSetScalar.h

@@ -70,11 +70,15 @@ public:
     double getMin() const;
 
     /**
-     * Returns the histogram of this dataset's valueset. If it does not exist yet, it will be created.
+     * Returns the histogram of this dataset's valueset. If it does not exist yet, it will be created and cached. It does NOT make use of the
+     * WValueSetHistogram down scaling feature even though the number of buckets might be lower than the default as the down scaling might
+     * introduce errors. To use down-scaling, grab the default histogram and call WValueSetHistogram( getHistogram(), buckets ) manually.
+     *
+     * \param buckets the number of buckets inside the histogram.
      *
      * \return the histogram.
      */
-    boost::shared_ptr< const WValueSetHistogram > getHistogram();
+    boost::shared_ptr< const WValueSetHistogram > getHistogram( size_t buckets = 1000 );
 
     /**
      * Interpolate the value fo the valueset at the given position.
@@ -124,9 +128,9 @@ protected:
 private:
 
     /**
-     * The histogram for later use.
+     * The histograms for later use. Each histogram for a requested bucket count gets cached.
      **/
-    boost::shared_ptr< WValueSetHistogram > m_histogram;
+    std::map< size_t, boost::shared_ptr< WValueSetHistogram > > m_histograms;
 
     /**
      * The lock used for securely creating m_histogram on demand.