ArcGIS Pro 3.3 API Reference Guide
ArcGIS.Core.Data.Topology Namespace / TopologyEdge Class / GetLeftParentFeatures Method
Indicates whether all parent features that cover this edge are returned. If true, only polygons lying to the left of the edge will be returned. The default value is true.
Example

In This Topic
    GetLeftParentFeatures Method
    In This Topic
    Gets the set of parents (polygon features) that cover this edge. If boundedByEdge is true, then only polygons lying to the left of the edge will be returned. This method must be called on the MCT. Use QueuedTask.Run.
    Syntax
    public IReadOnlyList<FeatureInfo> GetLeftParentFeatures( 
       bool boundedByEdge
    )
    Public Function GetLeftParentFeatures( _
       Optional ByVal boundedByEdge As Boolean _
    ) As IReadOnlyList(Of FeatureInfo)

    Parameters

    boundedByEdge
    Indicates whether all parent features that cover this edge are returned. If true, only polygons lying to the left of the edge will be returned. The default value is true.

    Return Value

    The set of parents (polygon features) that cover this edge. If boundedByEdge is true, then only polygons lying to the left of the edge will be returned.
    Exceptions
    ExceptionDescription
    A geodatabase-related exception has occurred.
    Example
    ExploreTopologyGraph
    public void ExploreTopologyGraph()
    {
      using (Geodatabase geodatabase = new Geodatabase(new FileGeodatabaseConnectionPath(new Uri(@"C:\TestData\GrandTeton.gdb"))))
      using (Topology topology = geodatabase.OpenDataset<Topology>("Backcountry_Topology"))
      {
        // Build a topology graph using the extent of the topology dataset.
    
        topology.BuildGraph(topology.GetExtent(), (topologyGraph) =>
        {
          using (Feature campsites12 = GetFeature(geodatabase, "Campsites", 12))
          {
            IReadOnlyList<TopologyNode> topologyNodesViaCampsites12 = topologyGraph.GetNodes(campsites12);
    
            TopologyNode topologyNodeViaCampsites12 = topologyNodesViaCampsites12[0];
    
            IReadOnlyList<TopologyEdge> allEdgesConnectedToNodeViaCampsites12 = topologyNodeViaCampsites12.GetEdges();
            IReadOnlyList<TopologyEdge> allEdgesConnectedToNodeViaCampsites12CounterClockwise = topologyNodeViaCampsites12.GetEdges(false);
    
            System.Diagnostics.Debug.Assert(allEdgesConnectedToNodeViaCampsites12.Count == allEdgesConnectedToNodeViaCampsites12CounterClockwise.Count);
    
            foreach (TopologyEdge edgeConnectedToNodeViaCampsites12 in allEdgesConnectedToNodeViaCampsites12)
            {
              TopologyNode fromNode = edgeConnectedToNodeViaCampsites12.GetFromNode();
              TopologyNode toNode = edgeConnectedToNodeViaCampsites12.GetToNode();
    
              bool fromNodeIsTheSameAsTopologyNodeViaCampsites12 = (fromNode == topologyNodeViaCampsites12);
              bool toNodeIsTheSameAsTopologyNodeViaCampsites12 = (toNode == topologyNodeViaCampsites12);
    
              System.Diagnostics.Debug.Assert(fromNodeIsTheSameAsTopologyNodeViaCampsites12 || toNodeIsTheSameAsTopologyNodeViaCampsites12,
                "The FromNode *or* ToNode of each edge connected to 'topologyNodeViaCampsites12' should be the same as 'topologyNodeViaCampsites12' itself.");
    
              IReadOnlyList<FeatureInfo> leftParentFeaturesBoundedByEdge = edgeConnectedToNodeViaCampsites12.GetLeftParentFeatures();
              foreach (FeatureInfo featureInfo in leftParentFeaturesBoundedByEdge)
              {
                System.Diagnostics.Debug.Assert(!String.IsNullOrEmpty(featureInfo.FeatureClassName));
                System.Diagnostics.Debug.Assert(featureInfo.ObjectID > 0);
                EnsureShapeIsNotEmpty(featureInfo);
              }
    
              IReadOnlyList<FeatureInfo> leftParentFeaturesNotBoundedByEdge = edgeConnectedToNodeViaCampsites12.GetLeftParentFeatures(false);
              foreach (FeatureInfo featureInfo in leftParentFeaturesNotBoundedByEdge)
              {
                System.Diagnostics.Debug.Assert(!String.IsNullOrEmpty(featureInfo.FeatureClassName));
                System.Diagnostics.Debug.Assert(featureInfo.ObjectID > 0);
                EnsureShapeIsNotEmpty(featureInfo);
              }
    
              IReadOnlyList<FeatureInfo> rightParentFeaturesBoundedByEdge = edgeConnectedToNodeViaCampsites12.GetRightParentFeatures();
              foreach (FeatureInfo featureInfo in rightParentFeaturesBoundedByEdge)
              {
                System.Diagnostics.Debug.Assert(!String.IsNullOrEmpty(featureInfo.FeatureClassName));
                System.Diagnostics.Debug.Assert(featureInfo.ObjectID > 0);
                EnsureShapeIsNotEmpty(featureInfo);
              }
    
              IReadOnlyList<FeatureInfo> rightParentFeaturesNotBoundedByEdge = edgeConnectedToNodeViaCampsites12.GetRightParentFeatures(false);
              foreach (FeatureInfo featureInfo in rightParentFeaturesNotBoundedByEdge)
              {
                System.Diagnostics.Debug.Assert(!String.IsNullOrEmpty(featureInfo.FeatureClassName));
                System.Diagnostics.Debug.Assert(featureInfo.ObjectID > 0);
                EnsureShapeIsNotEmpty(featureInfo);
              }
            }
          }
        });
      }
    }
    
    private void EnsureShapeIsNotEmpty(FeatureInfo featureInfo)
    {
      using (Feature feature = featureInfo.GetFeature())
      {
        System.Diagnostics.Debug.Assert(!feature.GetShape().IsEmpty, "The feature's shape should not be empty.");
      }
    }
    
    Requirements

    Target Platforms: Windows 11, Windows 10

    ArcGIS Pro version: 3 or higher.
    See Also