[Geometry snapper] Don't delete vertices if this would result in a de…

…generate geometry
qgis · Jul 13, 2016 · d5869cf · d5869cf
1 parent 258c899
commit d5869cf
Showing 1 changed file with 13 additions and 4 deletions.
diff --git a/src/plugins/geometry_snapper/qgsgeometrysnapper.cpp b/src/plugins/geometry_snapper/qgsgeometrysnapper.cpp
@@ -206,6 +206,7 @@ void QgsGeometrySnapper::processFeature( QgsFeatureId id )
   {
     for ( int iRing = 0, nRings = subjGeom->ringCount( iPart ); iRing < nRings; ++iRing )
     {
+      bool ringIsClosed = subjGeom->vertexAt( QgsVertexId( iPart, iRing, 0 ) ) == subjGeom->vertexAt( QgsVertexId( iPart, iRing, subjGeom->vertexCount( iPart, iRing ) - 1 ) );
       for ( int iVert = 0, nVerts = polyLineSize( subjGeom, iPart, iRing ); iVert < nVerts; ++iVert )
       {
         int iPrev = ( iVert - 1 + nVerts ) % nVerts;
@@ -219,10 +220,18 @@ void QgsGeometrySnapper::processFeature( QgsFeatureId id )
              subjPointFlags[iPart][iRing][iNext] != Unsnapped &&
              QgsGeometryUtils::sqrDistance2D( QgsGeometryUtils::projPointOnSegment( pMid, pPrev, pNext ), pMid ) < 1E-12 )
         {
-          subjGeom->deleteVertex( QgsVertexId( iPart, iRing, iVert ) );
-          subjPointFlags[iPart][iRing].removeAt( iVert );
-          iVert -= 1;
-          nVerts -= 1;
+          if (( ringIsClosed && nVerts > 3 ) || ( !ringIsClosed && nVerts > 2 ) )
+          {
+            subjGeom->deleteVertex( QgsVertexId( iPart, iRing, iVert ) );
+            subjPointFlags[iPart][iRing].removeAt( iVert );
+            iVert -= 1;
+            nVerts -= 1;
+          }
+          else
+          {
+            // Don't delete vertices if this would result in a degenerate geometry
+            break;
+          }
         }
       }
     }