自定义捕捉对象动态Jig绘制，实现实时更具选择对象变化预览图块

1、自定义靶框对象

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

//CAD开发库
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.Windows;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.GraphicsInterface;

//CAD开发基础库
using BaseLibrary.Runtime;
using BaseLibrary.ResultData;
using BaseLibrary.ExtensionMethod;
using BaseLibrary.Filter;

namespace TSTJig
{
    public class BaseGlyph : Glyph
    {
        public override void SetLocation(Point3d point)
        {

        }

        protected override void SubViewportDraw(ViewportDraw vd)
        {

        }
    }
}

2、自定义JIg对象

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
//CAD开发库
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.Windows;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.DatabaseServices;

//CAD开发基础库
using BaseLibrary.Runtime;
using BaseLibrary.ResultData;
using BaseLibrary.ExtensionMethod;
using BaseLibrary.Filter;

namespace TSTJig
{
    class SnapEntityJig : EntityJig
    {
        private Point3d m_Position;
        private Vector3d m_Direction;   //块方向
        private Curve m_Curve = null;


        public SnapEntityJig(Entity entity) : base(entity)
        {
            //((Circle)Entity).Center = m_CenterPt;
            //((Circle)Entity).Radius = m_Radius;
            

            //创建自定义对象捕捉模式
            CustomObjectSnapMode mode = new CustomObjectSnapMode("third", "_third", "三分之一", new BaseGlyph());
            //捕捉模式的实体类型为曲线
            mode.ApplyToEntityType(RXClass.GetClass(typeof(Curve)), CurveSnap);
            //开启自定义对象捕捉模式
            CustomObjectSnapMode.Activate("_third");
        }

        public void CurveSnap(ObjectSnapContext context, ObjectSnapInfo result)
        {
            m_Curve = (Curve)context.PickedObject;//当前捕捉到的曲线对象
            //Point3dCollection snaps = result.SnapPoints;//获取对象的捕捉点集合
            //                                            //Curve3dCollection snapCurves = result.SnapCurves;

            //if (curve.Closed) return;//如果为闭合曲线，则返回
            //double startParam = curve.StartParam;//曲线的起点参数
            //double endParam = curve.EndParam;//曲线的终点参数




            //if (context.LastPoint != null) {
            //    ed.Ex_WriteMessage("LastPoint" + context.LastPoint.ToString());
            //    string str = context.LastPoint.ToString();
            //}
            //if (context.PickPoint != null) {
            //    ed.Ex_WriteMessage("PickPoint" + context.PickPoint.ToString());
            //    string str = context.LastPoint.ToString();
            //}
            //ed.Ex_WriteMessage(snaps.Count);



            //将与曲线起点的距离为1/3曲线长度的点作为捕捉点
            //snaps.Add(curve.GetPointAtParameter(startParam + ((endParam - startParam) / 3)));
            //将与曲线起点的距离为2/3曲线长度的点作为捕捉点
            //snaps.Add(curve.GetPointAtParameter(startParam + ((endParam - startParam) * 2 / 3)));
            //ed.Ex_WriteMessage(context.PickPoint.ToString());
        }

        public void StopSnap()
        {
            //关闭自定义对象捕捉模式
            CustomObjectSnapMode.Deactivate("_third");
        }

        protected override SamplerStatus Sampler(JigPrompts prompts)
        {
            JigPromptPointOptions optJig = new JigPromptPointOptions();
            // 用AcquirePoint函数得到用户输入的点.
            PromptPointResult resJigDis = prompts.AcquirePoint(optJig);
            Point3d curPt = resJigDis.Value; //获取满足输入选项的输入值

            if (resJigDis.Status == PromptStatus.Cancel)
            {
                return SamplerStatus.Cancel;
            }

            if (m_Position != curPt)
            {
                if (m_Curve != null) {
                    if (m_Curve.Ex_IsCurvePoint(m_Position)) {
                        m_Direction = m_Curve.Ex_GetPerpendicularVector(m_Position); //获取垂直向量
                    }
                }
                // 保存当前点.
                m_Position = curPt;
                return SamplerStatus.OK;
            }
            else
            {
                return SamplerStatus.NoChange;
            }
        }

        protected override bool Update()
        {
            ((BlockReference)Entity).Position = m_Position;
            ((BlockReference)Entity).Rotation = m_Direction.AngleOnPlane(new Plane());

            return true;
        }
    }
}

3、测试：创建测试图块TST，执行TSTSnapEntityJig

  [CommandMethod("TSTSnapEntityJig")]
        public void TSTSnapEntityJig() {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            Database db = HostApplicationServices.WorkingDatabase;
            DocumentLock Lock = Application.DocumentManager.GetDocument(db).LockDocument(); //非模态模式，修改文件前进行上锁操作
                using (Transaction trans = doc.TransactionManager.StartTransaction())
                {
                    BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForWrite);
                    BlockTableRecord btr = (BlockTableRecord)trans.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
                string blockName = "TST";
                if (bt.Has(blockName))
                    {
                        //第一个状态，实现
                        BlockReference br = new BlockReference(Point3d.Origin, bt[blockName]);
                    SnapEntityJig blockJig = new SnapEntityJig(br);
                        PromptResult resJig = ed.Drag(blockJig);
                        if (resJig.Status == PromptStatus.Cancel)
                        {
                            blockJig.StopSnap();
                            return;
                        }
                        if (resJig.Status == PromptStatus.OK)
                        {
                            blockJig.StopSnap();
                        }
                    }
                    trans.Commit();
                }
            Lock.Dispose();
        }