ArcGIS Pro 2.9 API Reference Guide
BuildGraph Method
Example 

ArcGIS.Core.Data.Topology Namespace > Topology Class : BuildGraph Method
The area of interest for which a topology graph is built. It must be either ArcGIS.Core.Geometry.GeometryType.Envelope or ArcGIS.Core.Geometry.GeometryType.Polygon.
The client callback that receives a TopologyGraph as input for analysis.
Creates an in-memory representation of the topologically-integrated features within the current topology for a given area. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
public void BuildGraph( 
   Geometry extent,
   Action<TopologyGraph> callBack
)
Public Sub BuildGraph( _
   ByVal extent As Geometry, _
   ByVal callBack As Action(Of TopologyGraph) _
) 

Parameters

extent
The area of interest for which a topology graph is built. It must be either ArcGIS.Core.Geometry.GeometryType.Envelope or ArcGIS.Core.Geometry.GeometryType.Polygon.
callBack
The client callback that receives a TopologyGraph as input for analysis.
Exceptions
ExceptionDescription

extent is null.

-or-

callBack is null.

extent is not ArcGIS.Core.Geometry.GeometryType.Envelope or ArcGIS.Core.Geometry.GeometryType.Polygon.
A geodatabase-related exception has occurred.
Remarks
The life time of the TopologyGraph as input for callBack is scoped to that of the client callback itself. Once the flow of execution has returned from the callback, the TopologyGraph object will be disposed. Hence, attempting to use the TopologyGraph outside of this scope will raise a ArcGIS.Core.ObjectDisconnectedException.
Example
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, Windows 8.1

See Also

Reference

Topology Class
Topology Members