请用C#语言，写一段完整代码，实现CAD拾取点填充的功能

以下是一个使用C#语言实现CAD拾取点填充的示例代码。请注意，这只是一个示例，需要根据实际需要进行修改和调整。

using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;

namespace MyCommands
{
    public class MyCommandsClass
    {
        [CommandMethod("FILL")]
        public void FillCommand()
        {
            // 获取当前文档和编辑器对象
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Editor ed = doc.Editor;

            // 提示用户选择要填充的区域
            PromptEntityOptions peo = new PromptEntityOptions("\n选择要填充的区域: ");
            peo.SetRejectMessage("\n请选择一个封闭的区域.");
            peo.AddAllowedClass(typeof(Polyline), true);
            peo.AddAllowedClass(typeof(Circle), true);
            peo.AddAllowedClass(typeof(Arc), true);
            peo.AllowNone = false;

            PromptEntityResult per = ed.GetEntity(peo);

            if (per.Status != PromptStatus.OK)
                return;

            // 获取实体对象
            Entity ent = (Entity)doc.TransactionManager.GetObject(per.ObjectId, OpenMode.ForWrite);

            // 判断实体是否是封闭的
            if (!ent.Closed)
            {
                ed.WriteMessage("\n选择的实体不是封闭的，请重新选择.");
                return;
            }

            // 提示用户选择填充样式
            PromptKeywordOptions pko = new PromptKeywordOptions("\n选择填充样式: ");
            pko.Keywords.Add("SOLID");
            pko.Keywords.Add("HATCH");
            pko.AllowNone = false;

            PromptResult pkr = ed.GetKeywords(pko);

            if (pkr.Status != PromptStatus.OK)
                return;

            // 创建填充对象
            using (Transaction tr = doc.TransactionManager.StartTransaction())
            {
                BlockTableRecord btr = (BlockTableRecord)doc.Database.CurrentSpaceId.GetObject(OpenMode.ForWrite);

                Hatch hatch = new Hatch();
                hatch.SetDatabaseDefaults();

                if (pkr.StringResult == "SOLID")
                {
                    hatch.PatternScale = 1;
                    hatch.PatternAngle = 0;
                    hatch.PatternType = HatchPatternType.PreDefined;
                    hatch.SetHatchPattern(HatchPatternType.PreDefined, "SOLID");
                }
                else if (pkr.StringResult == "HATCH")
                {
                    // TODO: 选择填充图案和颜色
                }

                btr.AppendEntity(hatch);
                tr.AddNewlyCreatedDBObject(hatch, true);

                // 添加选择的区域
                hatch.AppendLoop(HatchLoopTypes.Default, new ObjectIdCollection() { ent.ObjectId });

                // 设置填充的属性
                hatch.EvaluateHatch(true);
                hatch.ColorIndex = 1;
                hatch.Layer = "0";

                tr.Commit();
            }

            ed.WriteMessage("\n填充完成.");
        }
    }
}