参考文章：CadLib 3.5 documentation/doc/cadlib3.5/Index.aspx
读取：定义DxfModel类型的变量model，使用DxfReader或DwgReader的Read(String)读取dxf或dwg格式的CAD文件filename。
显示：使用GIDGraphics3D类来显示CAD文件，基本步骤：
1、使用CreateDrawables(DxfModel)创建中间可绘制对象（点/线/折线）。
2、使用BoundingBox（Bounds3D）方法获取bounding box。
3、使用GetScaleTransform(Point3D, Point3D, Point3D, Point3D, Point3D, Point3D)计算将绘图拟合到显示矩形中所需的缩放变换，使用To2Dtransform属性设置结果。（写一个函数CalculateTo2DTransform）
4、使用Draw(Graphics, Rectangle)绘制中间可绘制对象。
注意：需要重写控件的Resize和Paint事件。
//Read and view CAD file 读和显示CAD文件private Matrix4D modelTransform = Matrix4D.Identity;private GDIGraphics3D gdiGraphics3D;private DxfModel model;//定义DxfModel对象private Bounds3D bounds;private string filename;//计算GDIGraphics3D的属性To2DTransformprivate void CalculateTo2DTransform(){if (bounds != null){//计算将CAD文件放入显示矩阵中需要的缩放比例变换Matrix4D to2DTransform = DxfUtil.GetScaleTransform(bounds.Corner1,bounds.Corner2,bounds.Center,new Point3D(0d, this.xtraTabPage3.Height, 0d),new Point3D(this.xtraTabPage3.Width, 0d, 0d),new Point3D(this.xtraTabPage3.Width / 2, this.xtraTabPage3.Height / 2, 0d));gdiGraphics3D.To2DTransform = to2DTransform * modelTransform;}}//打开CAD文件private void barButtonItem1_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e){//选取要打开的CAD文件OpenFileDialog dialog = new OpenFileDialog();dialog.Filter = "AutoCad files (*.dwg, *.dxf)|*.dxf;*.dwg";if (dialog.ShowDialog() == DialogResult.OK){filename = dialog.FileName;}if (!string.IsNullOrEmpty(filename)){try{//通过文件扩展名判断CAD文件是dwg格式还是dxf格式string extension = Path.GetExtension(filename);if (pare(extension, ".dwg", true) == 0)model = DwgReader.Read(filename);elsemodel = DxfReader.Read(filename);//将控件的标签添加上文件名this.xtraTabPage3.Text = "二维仿真(" + Path.GetFileName(filename) + ")";//设置控件背景为黑色this.xtraTabPage3.BackColor = System.Drawing.Color.Black;//使用GDIGraphics3D绘制CAD文件的方法//创建中间可绘制对象gdiGraphics3D.CreateDrawables(model);//获得bounding boxbounds = new Bounds3D();gdiGraphics3D.BoundingBox(bounds, modelTransform);//计算GDIGraphics3D的属性To2DTransformCalculateTo2DTransform();//响应控件的Paint事件，画CAD文件}catch (Exception ex){MessageBox.Show("文件有错！请用AutoCad打开，通过“文件-核查”尝试修复。错误信息：" + ex.Message);}}}//xtraTabPage3控件的Paint事件，画CAD文件private void xtraTabPage3_Paint(object sender, PaintEventArgs e){gdiGraphics3D.Draw(e.Graphics, this.xtraTabPage3.ClientRectangle);}//使绘制的CAD文件适应屏幕private void xtraTabPage3_Resize(object sender, EventArgs e){base.OnResize(e);CalculateTo2DTransform();this.xtraTabPage3.Invalidate();}
