Fix regression with snapping on intersection (fixes #13020)

Author: wonder-sk

src/core/geometry/qgsgeos.cpp

@@ -20,6 +20,7 @@ email                : marco.hugentobler at sourcepole dot com
 #include "qgslinestringv2.h"
 #include "qgsmessagelog.h"
 #include "qgsmulticurvev2.h"
+#include "qgsmultilinestringv2.h"
 #include "qgsmultipointv2.h"
 #include "qgsmultipolygonv2.h"
 #include "qgslogger.h"
@@ -821,17 +822,17 @@ QgsAbstractGeometryV2* QgsGeos::fromGeos( const GEOSGeometry* geos )
     }
     case GEOS_MULTILINESTRING:
     {
-      QgsMultiCurveV2* multiCurve = new QgsMultiCurveV2();
+      QgsMultiLineStringV2* multiLineString = new QgsMultiLineStringV2();
       int nParts = GEOSGetNumGeometries_r( geosinit.ctxt, geos );
       for ( int i = 0; i < nParts; ++i )
       {
         QgsLineStringV2* line = sequenceToLinestring( GEOSGetGeometryN_r( geosinit.ctxt, geos, i ), hasZ, hasM );
         if ( line )
         {
-          multiCurve->addGeometry( line );
+          multiLineString->addGeometry( line );
         }
       }
-      return multiCurve;
+      return multiLineString;
     }
     case GEOS_MULTIPOLYGON:
     {

tests/src/core/testqgssnappingutils.cpp

@@ -170,6 +170,52 @@ class TestQgsSnappingUtils : public QObject
       QVERIFY( !m2.isValid() );
     }
 
+    void testSnapOnIntersection()
+    {
+      // testing with a layer with two crossing linestrings
+      // (0,1)  x  x (1,1)
+      //         \/
+      //         /\    .
+      // (0,0)  x  x (1,0)
+      QgsVectorLayer* vl = new QgsVectorLayer( "LineString", "x", "memory" );
+      QgsPolyline polyline1, polyline2;
+      polyline1 << QgsPoint( 0, 0 ) << QgsPoint( 1, 1 );
+      polyline2 << QgsPoint( 1, 0 ) << QgsPoint( 0, 1 );
+      QgsFeature f1;
+      f1.setGeometry( QgsGeometry::fromPolyline( polyline1 ) );
+      QgsFeature f2;
+      f2.setGeometry( QgsGeometry::fromPolyline( polyline2 ) );
+      QgsFeatureList flist;
+      flist << f1 << f2;
+      vl->dataProvider()->addFeatures( flist );
+
+      QVERIFY( vl->dataProvider()->featureCount() == 2 );
+
+      QgsMapSettings mapSettings;
+      mapSettings.setOutputSize( QSize( 100, 100 ) );
+      mapSettings.setExtent( QgsRectangle( 0, 0, 1, 1 ) );
+      QVERIFY( mapSettings.hasValidSettings() );
+
+      QgsSnappingUtils u;
+      u.setMapSettings( mapSettings );
+      u.setSnapToMapMode( QgsSnappingUtils::SnapAdvanced );
+      QList<QgsSnappingUtils::LayerConfig> layers;
+      layers << QgsSnappingUtils::LayerConfig( vl, QgsPointLocator::Vertex, 0.1, QgsTolerance::MapUnits );
+      u.setLayers( layers );
+
+      // no snapping on intersections by default - should find nothing
+      QgsPointLocator::Match m = u.snapToMap( QgsPoint( 0.45, 0.5 ) );
+      QVERIFY( !m.isValid() );
+
+      u.setSnapOnIntersections( true );
+
+      QgsPointLocator::Match m2 = u.snapToMap( QgsPoint( 0.45, 0.5 ) );
+      QVERIFY( m2.isValid() );
+      QCOMPARE( m2.type(), QgsPointLocator::Vertex );
+      QCOMPARE( m2.point(), QgsPoint( 0.5, 0.5 ) );
+
+      delete vl;
+    }
 };
 
 QTEST_MAIN( TestQgsSnappingUtils )