Fix for bug that crashed qgis when moving the first/last vertex of a line

mhugent · mhugent · commit c41d416d1d89 · 2008-01-29T08:58:15.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk@8088 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -2824,10 +2824,16 @@ void QgsVectorLayer::snapToGeometry(const QgsPoint& startPoint, int featureId, Q
 	{
 	  snappingResultVertex.snappedVertex = snappedPoint;
 	  snappingResultVertex.snappedVertexNr = atVertex;
-	  snappingResultVertex.beforeVertex = geom->vertexAt(beforeVertex);
 	  snappingResultVertex.beforeVertexNr = beforeVertex;
-	  snappingResultVertex.afterVertex = geom->vertexAt(afterVertex);
+	  if(beforeVertex != -1) //make sure the vertex is valid
+	    {
+	      snappingResultVertex.beforeVertex = geom->vertexAt(beforeVertex);
+	    }
 	  snappingResultVertex.afterVertexNr = afterVertex;
+	  if(afterVertex != -1) //make sure the vertex is valid
+	    {
+	      snappingResultVertex.afterVertex = geom->vertexAt(afterVertex);
+	    }
 	  snappingResultVertex.snappedAtGeometry = featureId;
 	  snappingResultVertex.layer = this;
 	}
