C# AutoCAD2010 选择图中的块获取其位置后，将其替换成选择的外部块，其他和他名称相同但位置不同的块不替换完整代码

以下是实现该功能的示例代码：

// 获取当前文档和数据库
Document doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
Database db = doc.Database;

// 选择要替换的块和外部块
PromptEntityOptions peo = new PromptEntityOptions("\n选择要替换的块: ");
peo.SetRejectMessage("\n请选择块实体.");
peo.AddAllowedClass(typeof(BlockReference), true);
PromptEntityResult per = doc.Editor.GetEntity(peo);
if (per.Status != PromptStatus.OK) return;
ObjectId oldBlockId = per.ObjectId;

PromptStringOptions pso = new PromptStringOptions("\n输入要替换的外部块名: ");
pso.AllowSpaces = true;
PromptResult pr = doc.Editor.GetString(pso);
if (pr.Status != PromptStatus.OK) return;
string newBlockName = pr.StringResult;

// 打开外部文件并获取指定名称的块的 ObjectId
ObjectId newBlockId = ObjectId.Null;
using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
    if (bt.Has(newBlockName))
    {
        BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[newBlockName], OpenMode.ForRead);
        if (!btr.IsLayout)
        {
            newBlockId = btr.ObjectId;
        }
    }
    tr.Commit();
}
if (newBlockId.IsNull)
{
    doc.Editor.WriteMessage("\n未找到指定名称的块.");
    return;
}

// 获取要替换的块的位置和名称
BlockReference oldBlockRef = (BlockReference)oldBlockId.GetObject(OpenMode.ForRead);
Point3d oldPosition = oldBlockRef.Position;
string oldName = oldBlockRef.Name;

// 遍历块表记录，替换同名但位置不同的块
using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
    foreach (ObjectId btrId in bt)
    {
        BlockTableRecord btr = (BlockTableRecord)tr.GetObject(btrId, OpenMode.ForRead);
        if (!btr.IsLayout && btr.Name == oldName)
        {
            foreach (ObjectId entId in btr)
            {
                Entity ent = entId.GetObject(OpenMode.ForRead) as Entity;
                if (ent == null || ent.IsErased || ent.GetType() != typeof(BlockReference)) continue;
                BlockReference blockRef = (BlockReference)ent;
                if (blockRef.Position == oldPosition)
                {
                    blockRef.UpgradeOpen();
                    blockRef.BlockTableRecord = newBlockId;
                    blockRef.DowngradeOpen();
                }
            }
        }
    }
    tr.Commit();
}

注：此示例仅适用于 AutoCAD 2010 版本，请根据实际情况进行调整。