Make TIN interpolation more robust in case of NULL values and data distribution on lines. Minor change in qgsvectordataprovider.cpp to directly request a const iterator

git-svn-id: http://svn.osgeo.org/qgis/trunk@10904 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: mhugent

src/core/qgsvectordataprovider.cpp

@@ -222,7 +222,7 @@ int QgsVectorDataProvider::fieldNameIndex( const QString& fieldName ) const
 {
   const QgsFieldMap &theFields = fields();
 
-  for ( QgsFieldMap::const_iterator it = theFields.begin(); it != theFields.end(); ++it )
+  for ( QgsFieldMap::const_iterator it = theFields.constBegin(); it != theFields.constEnd(); ++it )
   {
     if ( it->name() == fieldName )
     {

src/plugins/interpolation/qgsinterpolator.cpp

@@ -93,9 +93,9 @@ int QgsInterpolator::cacheBaseData()
       {
         QgsAttributeMap attMap = theFeature.attributeMap();
         QgsAttributeMap::const_iterator att_it = attMap.find( mValueAttribute );
-        if ( att_it == attMap.end() ) //attribute not found, something must be wrong
+        if ( att_it == attMap.end() ) //attribute not found, something must be wrong (e.g. NULL value)
         {
-          return 3;
+          continue;
         }
         attributeValue = att_it.value().toDouble( &attributeConversionOk );
         if ( !attributeConversionOk || isnan( attributeValue ) ) //don't consider vertices with attributes like 'nan' for the interpolation

src/plugins/interpolation/qgstininterpolator.cpp

@@ -60,6 +60,8 @@ void QgsTINInterpolator::initialize()
     cacheBaseData();
   }
 
+  QList<Point3D*> rejectedPoints;
+
   //create DualEdgeTriangulation
 
   DualEdgeTriangulation* theDualEdgeTriangulation = new DualEdgeTriangulation( mCachedBaseData.size(), 0 );
@@ -70,7 +72,16 @@ void QgsTINInterpolator::initialize()
   for ( ; vertex_it != mCachedBaseData.constEnd(); ++vertex_it )
   {
     Point3D* thePoint = new Point3D( vertex_it->x, vertex_it->y, vertex_it->z );
-    mTriangulation->addPoint( thePoint );
+    if(mTriangulation->addPoint( thePoint ) == -100)
+    {
+      rejectedPoints.push_back(new Point3D(vertex_it->x, vertex_it->y, vertex_it->z));
+    }
+  }
+
+  QList<Point3D*>::iterator rejectedIt = rejectedPoints.begin();
+  for(; rejectedIt != rejectedPoints.end(); ++rejectedIt)
+  {
+    mTriangulation->addPoint(*rejectedIt);
   }
 
   mTriangleInterpolator = new LinTriangleInterpolator( theDualEdgeTriangulation );