AutoCAD.net: 实现AutoCAD Undo操作

      在命令行输入"UNDO"，会看到"Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]"，本文就利用"BEgin/End/Mark/Back”在ARX开发中实现Undo的操作。

 1. Undo 操作的结构：

• _BEgin
• _Mark
• _Undo
• _End

 2. 注意事项：

• 一组{_BEgin, _End}为一个操作单元，其内部不能再嵌套另一个{_BEgin, _End}。
• {_BEgin, _End}不能嵌在任何Transaction内部，但其内部可以嵌任意多个Transaction. 
• 最好一个_Mark标识一个Transaction.

3. SampleCode

using System;
using System.Collections.Generic;
using System.Text;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.GraphicsInterface;
using Autodesk.AutoCAD.Runtime;
using ArxApp = Autodesk.AutoCAD.ApplicationServices.Application;
using ObjectArxNet.Commons;

namespace ObjectArxNet.Test
{
    public class Undo
    {
        [CommandMethod("My_Undo")]
        public void InitCommand()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            try
            {
                //Use pick first
                PromptSelectionResult selectionRes = ed.SelectImplied();
                bool usePickfirst = false;

                if (selectionRes.Status == PromptStatus.OK)
                {
                    // If there was a pickfirst set, clear it
                    ed.SetImpliedSelection(new ObjectId[0]);

                    ObjectId[] objIds = selectionRes.Value.GetObjectIds();
                    if (objIds != null)
                    {
                        usePickfirst = objIds.Length > 0;
                    }
                }

                //Selection Options
                PromptSelectionOptions selOpt = new PromptSelectionOptions();
                selOpt.MessageForAdding = Consts.KEY_SELECT;
                selOpt.MessageForRemoval = Consts.KEY_SELECT;

                //Keyword Options
                PromptKeywordOptions optManual = new PromptKeywordOptions("\nSelect aligning mode");
                optManual.Keywords.Add(Consts.KEY_AUTO_SELECT, Consts.KEY_AUTO_SELECT, Consts.KEY_AUTO_SELECT_DIS);
                optManual.Keywords.Add(Consts.KEY_INSERT, Consts.KEY_INSERT, Consts.KEY_INSERT_DIS);
                optManual.Keywords.Add(Consts.KEY_UNDO, Consts.KEY_UNDO, Consts.KEY_UNDO);
                optManual.Keywords.Add(Consts.KEY_EXIT, Consts.KEY_EXIT, Consts.KEY_EXIT);
                optManual.AllowNone = false;
                optManual.Keywords.Default = Consts.KEY_AUTO_SELECT;

                PromptResult res = null;

                if (usePickfirst)
                {
                    Tools.RunCommand("_.UNDO", "_BEgin");
                    res = ed.GetKeywords(optManual);
                }
                else
                {
                    Tools.RunCommand("_.UNDO", "_BEgin");
                    PromptSelectionResult selRes = ed.GetSelection(selOpt); //, filter
                    if (selRes.Status == PromptStatus.OK)
                    {
                        ObjectId[] objIds = selRes.Value.GetObjectIds();
                        if (objIds != null)
                        {
                            res = ed.GetKeywords(optManual);
                        }
                    }
                }

                while (res != null && res.Status == PromptStatus.OK)
                {
                    switch (res.StringResult)
                    {
                        case Consts.KEY_AUTO_SELECT:
                            {
                                Tools.RunCommand("_.UNDO", "_Mark");
                                Tools.WriteLine(string.Format("DO: {0}", Consts.KEY_AUTO_SELECT));

                                res = ed.GetKeywords(optManual);
                                break;
                            }
                        case Consts.KEY_INSERT:
                            {
                                Tools.RunCommand("_.UNDO", "_Mark");
                                Tools.WriteLine(string.Format("DO: {0}", Consts.KEY_INSERT));

                                res = ed.GetKeywords(optManual);
                                break;
                            }
                        case Consts.KEY_REMOVE:
                            {
                                Tools.RunCommand("_.UNDO", "_Mark");
                                Tools.WriteLine(string.Format("DO: {0}", Consts.KEY_REMOVE));

                                res = ed.GetKeywords(optManual);
                                break;
                            }
                        case Consts.KEY_UNDO:
                            {
                                Tools.RunCommand("_.UNDO", "_Back");
                                Tools.WriteLine(string.Format("DO: {0}", Consts.KEY_UNDO));

                                doc.TransactionManager.QueueForGraphicsFlush();
                                res = ed.GetKeywords(optManual);
                                break;
                            }
                        case Consts.KEY_EXIT:
                            {
                                Tools.RunCommand("_.UNDO", "_End");//end the last
                                Tools.WriteLine(string.Format("DO: {0}", Consts.KEY_EXIT));
                                doc.TransactionManager.QueueForGraphicsFlush();

                                Tools.RunCommand("_.UNDO", "_BEgin");//begin the next
                                PromptSelectionResult selRes = ed.GetSelection(selOpt); //, filter
                                if (selRes.Status == PromptStatus.OK)
                                {
                                    ObjectId[] objIds = selRes.Value.GetObjectIds();
                                    if (objIds != null)
                                    {
                                        res = ed.GetKeywords(optManual);
                                    }
                                }
                                else
                                {
                                    return;
                                }
                                break;
                            }
                        default:
                            {
                                doc.TransactionManager.QueueForGraphicsFlush();
                                res = ed.GetKeywords(optManual);
                                break;
                            }
                    }
                }
            }
            finally
            {
                Tools.RunCommand("_.UNDO", "_End");
                ed.SelectionAdded -= new SelectionAddedEventHandler(callback_SelectionAdded);
            }
        }
    }
}