C# 二次开发cad填充代码

以下是C#二次开发CAD填充代码的示例：

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

namespace FillPolyline
{
    public class Commands
    {
        [CommandMethod("FillPolyline")]
        public void FillPolyline()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            // 选择多段线
            PromptEntityOptions peo = new PromptEntityOptions("\n选择多段线: ");
            peo.SetRejectMessage("\n必须选择一个多段线！");
            peo.AddAllowedClass(typeof(Polyline), true);
            PromptEntityResult per = ed.GetEntity(peo);
            if (per.Status != PromptStatus.OK) return;

            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                Polyline pline = tr.GetObject(per.ObjectId, OpenMode.ForWrite) as Polyline;
                if (pline == null) return;

                // 创建填充对象
                Hatch hatch = new Hatch();
                hatch.SetDatabaseDefaults();
                hatch.Layer = pline.Layer;
                hatch.ColorIndex = pline.ColorIndex;
                hatch.PatternScale = 1.0;

                // 设置填充类型
                hatch.PatternType = HatchPatternType.PreDefined;
                hatch.PatternName = "SOLID";

                // 获取多段线边界
                Point3dCollection pts = new Point3dCollection();
                for (int i = 0; i < pline.NumberOfVertices; i++)
                {
                    pts.Add(pline.GetPoint3dAt(i));
                }

                // 添加填充边界
                hatch.AppendLoop(HatchLoopTypes.Outermost, pts);

                // 将填充对象添加到模型空间
                BlockTableRecord btr = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
                btr.AppendEntity(hatch);
                tr.AddNewlyCreatedDBObject(hatch, true);

                // 关联填充对象和多段线
                hatch.Associative = true;
                hatch.AppendLoop(HatchLoopTypes.Default, new ObjectIdCollection() { pline.ObjectId });
                hatch.EvaluateHatch(true);

                tr.Commit();
            }
        }
    }
}

上述代码中，通过 `PromptEntityOptions` 和 `ed.GetEntity` 方法选择了一个多段线，然后创建了一个填充对象并将其添加到模型空间。最后，通过将填充对象与多段线关联，实现了填充功能。