Csharp c#, Autocad, 显示影线的属性

1. How can I access center of circle?
   Answer:
   Circle oCircle = tr.GetObject(id, OpenMode.ForRead) as Circle; var _centerPosition = oCircle.Center;

2. How can I get property of hatch?
   Answer:
   you need to change
   from hatch.AppendLoop(HatchLoopTypes.Outermost, ids);
   to hatch.AppendLoop(HatchLoopTypes.External, ids);

我更改了你的代码，它对我有效

public static void SelectCirclesToHatch()
    {
        var doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
        var db = doc.Database;
        var ed = doc.Editor;
        var filter = new SelectionFilter(new[] { new TypedValue(0, "CIRCLE") });
        var selection = ed.GetSelection(filter);
        int vr = 1;
        if (selection.Status != PromptStatus.OK) { return; }

        using (var tr = db.TransactionManager.StartTransaction())
        {
            var curSpace = (BlockTableRecord)tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
            foreach (var id in selection.Value.GetObjectIds())
            {
                try
                {
                    var ids = new ObjectIdCollection(new[] { id });
                    using (var hatch = new Hatch())
                    {
                        curSpace.AppendEntity(hatch);
                        tr.AddNewlyCreatedDBObject(hatch, true);
                        hatch.SetHatchPattern(HatchPatternType.PreDefined, "ANSI31");
                        hatch.Associative = true;
                        hatch.AppendLoop(HatchLoopTypes.External, ids);
                        hatch.EvaluateHatch(true);
                        hatch.HatchStyle = HatchStyle.Normal;

                        Circle oCircle = tr.GetObject(id, OpenMode.ForRead) as Circle;
                        var _centerPosition = oCircle.Center;

                        DBText acText = new DBText();
                        acText.Position = _centerPosition;

                        acText.TextString = hatch.Area.ToString(); // Area of hatch
                        acText.Height = 0.5;
                        curSpace.AppendEntity(acText);
                        tr.AddNewlyCreatedDBObject(acText, true);
                    }
                }
                catch { }
            }
            tr.Commit();
        }
    }