MaplexAnchorPointType Enumeration
Modify label's Leader Line Anchor point properties - Polygon geometry
//Note: call within QueuedTask.Run()
//Get the layer's definition
var lyrDefn = featureLayer.GetDefinition() as CIMFeatureLayer;
//Get the label classes - we need the first one
var listLabelClasses = lyrDefn.LabelClasses.ToList();
var theLabelClass = listLabelClasses.FirstOrDefault();
//If TextSymbol is a callout the leader line anachor point can be modified
theLabelClass.MaplexLabelPlacementProperties.PolygonAnchorPointType = MaplexAnchorPointType.Perimeter;
lyrDefn.LabelClasses = listLabelClasses.ToArray(); //Set the labelClasses back
featureLayer.SetDefinition(lyrDefn); //set the layer's definition
System.Object
System.ValueType
System.Enum
ArcGIS.Core.CIM.MaplexAnchorPointType
Target Platforms: Windows 11, Windows 10
ArcGIS Pro version: 3 or higher.