基于C#的AutoCAD二次开发之获取用户输入信息、选择集、访问CAD内部命令

    在CAD创建图形对象时，经常需要和用户进行交互，例如：直线创建时需要用户输入起点和终点（或长度）信息，复制对象时需要指定源对象等。
我的开发环境为Visual Studio 2017 & AutoCAD 2014 & AutoCAD 2020。

1. 点拾取

• 实现方法

方式一

PromptPointResult retStPoint = ed.GetPoint(("请输入点")); 

方式二

PromptPointOptions ppo = new PromptPointOptions("请输入点"); 
PromptPointResult retStPoint = ed.GetPoint(ppo);

• 效果展示

• 实例代码（获取手动交互的某点坐标，并标注）

类库

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

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

代码

[CommandMethod("PointCreated")]
public void ComputePointCreate()
{
    Editor ed = Autodesk.AutoCAD.ApplicationServices.Application.
        DocumentManager.MdiActiveDocument.Editor;
    PromptPointResult retStPoint = ed.GetPoint(("获得起点坐标"));
    if (retStPoint.Status != PromptStatus.OK)
        return;
    DBPoint pt = new DBPoint(retStPoint.Value);

    Database db = HostApplicationServices.WorkingDatabase;
    using (Transaction trans = db.TransactionManager.StartTransaction())
    {
        BlockTable bt = trans.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
        BlockTableRecord btr = trans.GetObject(bt[BlockTableRecord.ModelSpace],
            OpenMode.ForWrite) as BlockTableRecord;
        btr.AppendEntity(pt);
        trans.AddNewlyCreatedDBObject(pt, true);
        trans.Commit();
    }
}

• 其他要素
  其它信息获取方法

2. 选择集（读取鼠标框选选择集实体）

• 实现方法

//获取用户框选的选择集对象
PromptSelectionResult pers = ed.GetSelection();

• 实例代码（获取框选区的，线和多段线的数量）
  类库

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

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

代码

public Entity getEntityByObjId(Database db, ObjectId id)
{
    using (Transaction trans = db.TransactionManager.StartTransaction())
    {
        Entity dbo = trans.GetObject(id, OpenMode.ForRead) as Entity;
        trans.Commit();
        return dbo;
    }
    return null;
}

[CommandMethod("ModelCreated")]
public void ComputeModelCreated()
{
    Database db = HostApplicationServices.WorkingDatabase;
    Editor ed = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.Editor;
    //获取用户框选的选择集对象
    PromptSelectionResult pers = ed.GetSelection();
    if (pers.Status != PromptStatus.OK)//判断选择状态
        return;
    if (pers.Value == null)//判断选择集是否为空
        return;
    /*
    PromptEntityResult downEntity = ed.GetEntity("请选择起始线");
    if (downEntity.Status != PromptStatus.OK)
        return;
    */

    List<DBText> textArray = new List<DBText>();//注记
    List<Line> lineArray = new List<Line>();//线段
    List<Polyline> polylineArray = new List<Polyline>();//轻量）多段线
    List<Polyline2d> poly2dArray = new List<Polyline2d>();//拟合曲线
    List<Spline> splineArray = new List<Spline>();//曲线
    List<Point3d> pointArray = new List<Point3d>();//存储线段的点位置

    //获取输入对象的id或实体
    ObjectId[] oids = pers.Value.GetObjectIds();

    for (int ii = 0; ii < oids.Length; ii++)
    {
        ObjectId oid = oids[ii];
        Entity ent = getEntityByObjId(db, oid);
        if (ent == null)
            continue;

        if (ent is DBText)
        {
            textArray.Add(ent as DBText);
        }
        else if (ent is Line)
        {
            lineArray.Add(ent as Line);
        }
        else if (ent is Polyline)
        {
            polylineArray.Add(ent as Polyline);
        }
        else if (ent is Polyline2d)
        {
            poly2dArray.Add(ent as Polyline2d);
        }
        else if (ent is Spline)
        {
            splineArray.Add(ent as Spline);
        }
    }
    MessageBox.Show("线段共有" + lineArray.Count + "多段线有" + polylineArray.Count);
}

• 效果展示

3. 访问CAD内部命令

• 实现方式
  1）SendStringToExecute（.Net）
  2）SendCommand（COM方式）
  3）acedCommand（ P/Invoke非托管C++函数）

• 实现代码

[CommandMethod("CadCmdExecute")]
public void CadCmdExecute()
{
    //命令行动态执行语句
    Document doc = Autodesk.AutoCAD.ApplicationServices.Application.
        DocumentManager.MdiActiveDocument;
    //创建一个圆形圆形，并强制缩放视图至图形
    doc.SendStringToExecute("circle\n2,2,0\n4\n", true, false, true);
    doc.SendStringToExecute("zoom e\n", true, false, true);
}

4. 总结
   喜欢的朋友们可以点个关注，后续将持续更新，精彩无限^ - ^