Event layer function: catch various error cases for line offsets

Author: mhugent

src/analysis/vector/qgsgeometryanalyzer.cpp

@@ -986,6 +986,10 @@ bool QgsGeometryAnalyzer::eventLayer( QgsVectorLayer* lineLayer, QgsVectorLayer*
     if ( locationField2 != -1 )
     {
       measure2 = fet.attribute( locationField2 ).toDouble();
+      if ( qgsDoubleNear(( measure2 - measure1 ), 0.0 ) )
+      {
+        continue;
+      }
     }
 
     QList<QgsFeature> featureIdList = lineLayerIdMap.values( fet.attribute( eventField ).toString() );
@@ -1052,7 +1056,11 @@ void QgsGeometryAnalyzer::addEventLayerFeature( QgsFeature& feature, QgsGeometry
     {
       double offsetVal = feature.attribute( offsetField ).toDouble();
       offsetVal *= offsetScale;
-      createOffsetGeometry( *geomIt, lineGeom, offsetVal );
+      if ( !createOffsetGeometry( *geomIt, lineGeom, offsetVal ) )
+      {
+        delete *geomIt;
+        continue;
+      }
     }
 
     feature.setGeometry( *geomIt );
@@ -1072,11 +1080,11 @@ void QgsGeometryAnalyzer::addEventLayerFeature( QgsFeature& feature, QgsGeometry
   }
 }
 
-void QgsGeometryAnalyzer::createOffsetGeometry( QgsGeometry* geom, QgsGeometry* lineGeom, double offset )
+bool QgsGeometryAnalyzer::createOffsetGeometry( QgsGeometry* geom, QgsGeometry* lineGeom, double offset )
 {
   if ( !geom || !lineGeom )
   {
-    return;
+    return false;
   }
 
   QList<QgsGeometry*> inputGeomList;
@@ -1099,7 +1107,17 @@ void QgsGeometryAnalyzer::createOffsetGeometry( QgsGeometry* geom, QgsGeometry*
       //geos 3.3 needed for line offsets
 #if defined(GEOS_VERSION_MAJOR) && defined(GEOS_VERSION_MINOR) && \
       ((GEOS_VERSION_MAJOR>3) || ((GEOS_VERSION_MAJOR==3) && (GEOS_VERSION_MINOR>=3)))
-      outputGeomList.push_back( GEOSOffsetCurve(( *inputGeomIt )->asGeos(), -offset, 8 /*quadSegments*/, 0 /*joinStyle*/, 5.0 /*mitreLimit*/ ) );
+      GEOSGeometry* offsetGeom = GEOSOffsetCurve(( *inputGeomIt )->asGeos(), -offset, 8 /*quadSegments*/, 0 /*joinStyle*/, 5.0 /*mitreLimit*/ );
+      if ( !offsetGeom || !GEOSisValid( offsetGeom ) )
+      {
+        return false;
+      }
+      if ( !GEOSisValid( offsetGeom ) || GEOSGeomTypeId( offsetGeom ) != GEOS_LINESTRING || GEOSGeomGetNumPoints( offsetGeom ) < 1 )
+      {
+        GEOSGeom_destroy( offsetGeom );
+        return false;
+      }
+      outputGeomList.push_back( offsetGeom );
 #else
       outputGeomList.push_back( GEOSGeom_clone(( *inputGeomIt )->asGeos() ) );
 #endif
@@ -1143,6 +1161,7 @@ void QgsGeometryAnalyzer::createOffsetGeometry( QgsGeometry* geom, QgsGeometry*
     geom->fromGeos( collection );
     delete[] geomArray;
   }
+  return true;
 }
 
 QgsPoint QgsGeometryAnalyzer::createPointOffset( double x, double y, double dist, QgsGeometry* lineGeom ) const

src/analysis/vector/qgsgeometryanalyzer.h

@@ -150,7 +150,7 @@ class ANALYSIS_EXPORT QgsGeometryAnalyzer
         @param geom the geometry to modify
         @param lineGeom the line geometry to which the feature is referenced
         @param offset the offset value in layer unit. Negative values mean offset towards left, positive values offset to the right side*/
-    void createOffsetGeometry( QgsGeometry* geom, QgsGeometry* lineGeom, double offset );
+    bool createOffsetGeometry( QgsGeometry* geom, QgsGeometry* lineGeom, double offset );
     QgsPoint createPointOffset( double x, double y, double dist, QgsGeometry* lineGeom ) const;
     const unsigned char* locateBetweenWkbString( const unsigned char* ptr, QgsMultiPolyline& result, double fromMeasure, double toMeasure );
     const unsigned char* locateAlongWkbString( const unsigned char* ptr, QgsMultiPoint& result, double measure );