需要获取从AutoCAD Civil3D中的类创建的对象计数

Question

它是针对AutoCAD开发工具包的，为AutoCAD开发了一个插件。我已经将一些DWG文件加载到图形中，并创建了加载的类的一些对象。创建这些对象时，我添加了一个扩展数据，其中包含有关BlockTableRecord的一些信息。现在，我需要删除已从图形中删除的对象的BlockTableRecords。保存文档时，我收到来自AutoCAD的回调。在此回调中，我尝试遍历所有块表记录，以查找包含我们的信息的记录。以及包含使用我的外接程序创建的信息的记录，我正在尝试查看从该记录项创建的对象的数量。如果不存在，我将删除块表记录，或者至少更新我们的封装外形。

在这里，我无法获得从一个特定的表记录创建的对象的计数。以下是我到目前为止所做的工作。

private static void CommandExecutionCallBack(object sender, CommandEventArgs e)
{
    string commando = e.GlobalCommandName.ToLower();
    if (commando.Contains("save"))
    {
        Document doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
        var documentManager = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager;
        Editor ed = doc.Editor;
        Database db = doc.Database;
        Autodesk.AutoCAD.DatabaseServices.TransactionManager tm = db.TransactionManager;
        using (Transaction myT = tm.StartTransaction())
        {
            BlockTable bt = (BlockTable)tm.GetObject(db.BlockTableId, OpenMode.ForRead, false);
            SymbolTableEnumerator enumerator = bt.GetEnumerator();
            while (enumerator.MoveNext())
            {
                BlockTableRecord btr = tm.GetObject(enumerator.Current, OpenMode.ForRead, false) as BlockTableRecord;
                ResultBuffer xdata = btr.GetXDataForApplication(REGAPP_NAME);
                if (null != xdata)
                {

                    //Here I am trying to fetch the objects that exist against the selected btr.
                    AcadApplication acApp = Autodesk.AutoCAD.ApplicationServices.Application.AcadApplication as AcadApplication;
                    AcadDocument thisDrawing = acApp.ActiveDocument;


                    thisDrawing.SendCommand("(command MAPSELECTCLASSIFIED " + btr.Name + ")" + Environment.NewLine);
                    AcadSelectionSet selectionSet = thisDrawing.PickfirstSelectionSet;

                    //I am always getting selectionSet.Count as zero.
                    MessageBox.Show(btr.Name + " -> SelectionSet Count: " + selectionSet.Count.ToString());
                }
                else
                {
                    //Will ignore this condition. The current btr is not created by our add-in
                }
            }
        }
    }
}

在这方面的任何帮助都将不胜感激。

我从AutoCAD论坛https://forums.autodesk.com/t5/net/how-to-find-and-export-object-classess-from-drawing/m-p/5814774#M45948得到了一些帮助。

问候你，乌马尔

Answer 1

删除未引用的BlockTableRecord (或任何其他SymbolTableRecord)通常称为: Purge。数据库类提供了一个Purge()方法，可用于获取"purgeable“对象。

    private static ObjectIdCollection GetPurgeableBlocks(Database db)
    {
        var ids = new ObjectIdCollection();
        using (var tr = new OpenCloseTransaction())
        {
            var bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
            foreach (ObjectId id in bt)
            {
                var btr = (BlockTableRecord)tr.GetObject(id, OpenMode.ForRead);
                if (btr.GetXDataForApplication(REGAPP_NAME) != null)
                {
                    ids.Add(id);
                }
            }
            tr.Commit();
        }
        db.Purge(ids);
        return ids;
    }