CAD二次开发（2）-将直线对象添加到CAD图形文件

1. 准备工作

创建一个类库项目，如下：

2. 分析Line对象

Line类的初始化方法和参数

using Autodesk.AutoCAD.DatabaseServices;
Line line = new Line();

Line 继承Curve 继承Entity 继承DBObject 继承Drawable 继承RXObject

初始化方法有两个：

3. 启动项目

我们创建一个line对象，然后打上断点，生成.dll文件，加载到CAD中，然后执行命令。

我们就会发现，自动跳到了VS界面，代码走到了断点处，代码继续往下走，我们就会看到：

透过参数，我们就会发现默认Line创建了一个起点为（0,0），终点为（0,0）的直线。

4. 如何将线条写到CAD中

4.1 数据交互原理

首先我们要明白一个事情，就是我们在代码中创建的线条目前是写到内存当中，而CAD的图纸数据是以自己的某种方式，比如文件数据库等等，存储在磁盘中，所以我们就得需要把内存中的数据想办法按照CAD的API调用写到CAD的文件数据库中。

如上图的右边，就是CAD的文件数据存储的过程：Database（数据库）-》BlockTable（块表）-》BlockTableRecord（块表记录）-》Entity（实体数据）。

4.2 代码实现

所以代码如下：

using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace LineTest01
{public class LineTest{[CommandMethod("LineDemo")]public void LineDemo() {//创建线条对象Line line = new Line();//创建坐标对象Point3d start = new Point3d(200, 200, 200);Point3d end = new Point3d(430, 400, 400);//设置属性line.StartPoint = start;line.EndPoint = end;//声明图形数据库对象Document doc = Application.DocumentManager.MdiActiveDocument;Database database = doc.Database;//开启事务处理using (Transaction trans = database.TransactionManager.StartTransaction()) {//打开块表BlockTable  blockTable = (BlockTable)trans.GetObject(database.BlockTableId, OpenMode.ForRead);// 打开块表记录BlockTableRecord blockTableRecord = (BlockTableRecord)trans.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);//加直线到块表记录blockTableRecord.AppendEntity(line);//更新数据trans.AddNewlyCreatedDBObject(line, true);//事务提交trans.Commit();}}}
}

然后我们启动服务，加载CAD程序。

4.3 CAD加载.dll程序

输入：NETLOAD

选择.dll文件。

输入：LineDemo

就可以看到我们已经成功地将线条对象写入到CAD中了。

5. 封装工具类

从上面可以看到，其实我们可以将一些常用的方法，封装成公共方法，提高代码的复用性，这里我为大家封装了两个类，分别如下：

BaseTool.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace LineTest01
{internal static class BaseTool{/// <summary>/// 角度转成弧度/// </summary>/// <param name="degree">角度参数</param>/// <returns>弧度</returns>public static Double DegreeToAngle(this Double degree){return degree * Math.PI / 180;}/// <summary>/// 弧度转成角度/// </summary>/// <param name="degree">弧度参数</param>/// <returns>角度</returns>public static Double AngleToDegree(this Double angle){return angle * 180 / Math.PI;}}
}

AddEntityTool.cs

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace LineTest01
{//internal 表示只有在同一程序集的文件中才能访问internal static class AddEntityTool{/// <summary>/// 将图形对象添加到图形文件中/// </summary>/// <param name="db">图形数据库</param>/// <param name="entity">图形对象</param>/// <returns></returns>public static ObjectId AddEntityToModelSpace(this Database db, Entity entity) {//声明ObjectId,用于返回ObjectId objectId = ObjectId.Null;//开启事务using (Transaction trans = db.TransactionManager.StartTransaction()) {//打开块表BlockTable blockTable = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead);//打开块表记录BlockTableRecord blockTableRecord= (BlockTableRecord)trans.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);//添加图形到块表记录objectId = blockTableRecord.AppendEntity(entity);//更新数据信息trans.AddNewlyCreatedDBObject(entity, true);//提交事务trans.Commit();}return objectId;}/// <summary>/// 将图形对象添加到图形文件中/// </summary>/// <param name="db">图形数据库</param>/// <param name="entity">图形对象 可变参数</param>/// <returns>ObjectId</returns>public static ObjectId[] AddEntityToModelSpace(this Database db, params Entity[] entities){//声明ObjectId,用于返回ObjectId[] objectId = new ObjectId[entities.Length];//开启事务using (Transaction trans = db.TransactionManager.StartTransaction()){//打开块表BlockTable blockTable = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead);//打开块表记录BlockTableRecord blockTableRecord = (BlockTableRecord)trans.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);for (int i = 0; i < entities.Length; i++){//添加图形到块表记录objectId[i] = blockTableRecord.AppendEntity(entities[i]);//更新数据信息trans.AddNewlyCreatedDBObject(entities[i], true);}//提交事务trans.Commit();}return objectId;}/// <summary>/// 将图形对象添加到图形文件中/// </summary>/// <param name="db">图形数据库</param>/// <param name="startPoint">起点坐标</param>/// <param name="endPoint">终点坐标</param>/// <returns>ObjectId</returns>public static ObjectId AddEntityToModelSpace(this Database db, Point3d startPoint,Point3d endPoint){return db.AddEntityToModelSpace(new Line(startPoint, endPoint));}/// <summary>/// 将图形对象添加到图形文件中/// </summary>/// <param name="db">图形数据库</param>/// <param name="startPoint">起点坐标</param>/// <param name="length">直线长度</param>/// <param name="degree">与X轴正方向的夹角</param>/// <returns>ObjectId</returns>public static ObjectId AddEntityToModelSpace(this Database db, Point3d startPoint, Double length,Double degree){//计算终点坐标double X = startPoint.X + length * Math.Cos(degree.DegreeToAngle());double Y = startPoint.X + length * Math.Sin(degree.DegreeToAngle());Point3d endPoint = new Point3d(X, Y, 0);return db.AddEntityToModelSpace(new Line(startPoint, endPoint));}}
}

封装类的使用

        [CommandMethod("LineAdd")]public void LineAdd(){Database workingDatabase = HostApplicationServices.WorkingDatabase;Line line = new Line(new Point3d(100, 100, 0), new Point3d(200, 100, 0));workingDatabase.AddEntityToModelSpace(line);Line line1 = new Line(new Point3d(200, 100, 0), new Point3d(200, 200, 0));Line line2 = new Line(new Point3d(200, 100, 0), new Point3d(100, 100, 0));workingDatabase.AddEntityToModelSpace(line1,line2);}