difference: skip empty geometries, convert to multi-part geometries

wonder-sk · wonder-sk · commit 57e5b9f1a7af · 2018-04-25T09:58:27.000+02:00
diff --git a/src/analysis/processing/qgsoverlayutils.cpp b/src/analysis/processing/qgsoverlayutils.cpp
@@ -83,6 +83,10 @@ void QgsOverlayUtils::difference( const QgsFeatureSource &sourceA, const QgsFeat
         geom = geom.difference( geomB );
       }
 
+      // if geomB covers the whole source geometry, we get an empty geometry collection
+      if ( geom.isEmpty() )
+        continue;
+
       const QgsAttributes attrsA( featA.attributes() );
       switch ( outputAttrs )
       {
@@ -100,6 +104,7 @@ void QgsOverlayUtils::difference( const QgsFeatureSource &sourceA, const QgsFeat
       }
 
       QgsFeature outFeat;
+      geom.convertToMultiType();
       outFeat.setGeometry( geom );
       outFeat.setAttributes( attrs );
       sink.addFeature( outFeat, QgsFeatureSink::FastInsert );

Original file line number	Diff line number	Diff line change
`@@ -83,6 +83,10 @@ void QgsOverlayUtils::difference( const QgsFeatureSource &sourceA, const QgsFeat`
`83`	`83`	`geom = geom.difference( geomB );`
`84`	`84`	`}`
`85`	`85`
	`86`	`+ // if geomB covers the whole source geometry, we get an empty geometry collection`
	`87`	`+ if ( geom.isEmpty() )`
	`88`	`+ continue;`
	`89`	`+`
`86`	`90`	`const QgsAttributes attrsA( featA.attributes() );`
`87`	`91`	`switch ( outputAttrs )`
`88`	`92`	`{`
`@@ -100,6 +104,7 @@ void QgsOverlayUtils::difference( const QgsFeatureSource &sourceA, const QgsFeat`
`100`	`104`	`}`
`101`	`105`
`102`	`106`	`QgsFeature outFeat;`
	`107`	`+ geom.convertToMultiType();`
`103`	`108`	`outFeat.setGeometry( geom );`
`104`	`109`	`outFeat.setAttributes( attrs );`
`105`	`110`	`sink.addFeature( outFeat, QgsFeatureSink::FastInsert );`