C# AutoCAD 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

以下是一个示例代码，其中假设您已经使用 AutoCAD .NET API 打开了一个 DWG 文件，并且已经选择了一个要替换的块和一个外部块。

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

public void ReplaceBlock()
{
    // 获取当前文档和编辑器
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Editor acEditor = acDoc.Editor;

    // 提示用户选择要替换的块
    PromptEntityOptions peo = new PromptEntityOptions("\nSelect block to replace: ");
    peo.SetRejectMessage("\nSelected object is not a block.");
    peo.AddAllowedClass(typeof(BlockReference), true);
    PromptEntityResult per = acEditor.GetEntity(peo);

    if (per.Status != PromptStatus.OK)
        return;

    // 获取要替换的块的信息
    Transaction acTrans = acDoc.TransactionManager.StartTransaction();
    BlockReference acBlkRef = acTrans.GetObject(per.ObjectId, OpenMode.ForWrite) as BlockReference;
    string blkName = acBlkRef.Name;
    Point3d blkPosition = acBlkRef.Position;

    // 提示用户选择外部块
    PromptResult pr = acEditor.GetString("\nEnter name of external block: ");
    if (pr.Status != PromptStatus.OK)
        return;

    // 打开外部块的 DWG 文件并获取块的信息
    Database externalDb = new Database(false, true);
    externalDb.ReadDwgFile(pr.StringResult, System.IO.FileShare.ReadWrite, true, "");
    Transaction externalTrans = externalDb.TransactionManager.StartTransaction();
    BlockTable externalBt = externalTrans.GetObject(externalDb.BlockTableId, OpenMode.ForRead) as BlockTable;
    BlockTableRecord externalBtr = externalTrans.GetObject(externalBt[BlockTableRecord.ModelSpace], OpenMode.ForRead) as BlockTableRecord;
    BlockReference externalBlkRef = null;
    foreach (ObjectId externalId in externalBtr)
    {
        Entity externalEnt = externalTrans.GetObject(externalId, OpenMode.ForRead) as Entity;
        if (externalEnt is BlockReference && externalEnt.Layer == "0")
        {
            BlockReference externalTempBlkRef = externalEnt as BlockReference;
            if (externalTempBlkRef.Name == blkName)
            {
                externalBlkRef = externalTempBlkRef;
                break;
            }
        }
    }

    if (externalBlkRef == null)
    {
        acEditor.WriteMessage("\nExternal block not found.");
        return;
    }

    // 替换块
    foreach (ObjectId blkId in acBlkRef.BlockTableRecord)
    {
        Entity ent = acTrans.GetObject(blkId, OpenMode.ForWrite) as Entity;
        if (ent is BlockReference && ent.Layer == "0" && ent.Name == blkName && ent.Position == blkPosition)
        {
            acBlkRef.Erase();
            BlockReference newBlkRef = externalBlkRef.Clone() as BlockReference;
            newBlkRef.Position = blkPosition;
            acBlkRef = acTrans.GetObject(ent.Id, OpenMode.ForWrite) as BlockReference;
            acBlkRef.CopyFrom(newBlkRef);
            break;
        }
    }

    acTrans.Commit();
    externalTrans.Abort(); // 不需要提交
    externalDb.Dispose();
}

请注意，该代码仅替换与选定块名称和位置完全匹配的块。如果您想要替换名称相同但位置不同的块，则需要在 `foreach` 循环中添加更多的条件来判断块是否应该被替换。