CAD二次开发根据多个实体获取边界截图

//加下多个实体，获取所有实体矩形边界，获取边界点截图
        public void SnapShot(List entities ,string name) {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            Database db = HostApplicationServices.WorkingDatabase;
            Extents3d extents3D = new Extents3d();
            foreach (Entity ent in entities) {
                extents3D.AddExtents(ent.Bounds.Value);
            }
            Point3d P1 = new Point3d(extents3D.MinPoint.X - 2, extents3D.MinPoint.Y - 2, extents3D.MinPoint.Z);
            Point3d P2 = new Point3d(extents3D.MaxPoint.X + 2, extents3D.MaxPoint.Y + 2, extents3D.MaxPoint.Z);
            GetBitmapBy2Point(P1, P2, name);
        }
public void GetBitmapBy2Point(Point3d p1, Point3d p2,string filename)
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;
            ViewTableRecord cvtr = ed.GetCurrentView();
            ViewTableRecord vtr = new ViewTableRecord();

            vtr.Width = Math.Abs(p1.X - p2.X);
            vtr.Height = Math.Abs(p2.Y - p1.Y);
            vtr.CenterPoint = new Point2d((p1.X + p2.X) / 2, (p1.Y + p2.Y) / 2);
            ed.SetCurrentView(vtr);
            ed.Regen();
            var size = doc.Window.DeviceIndependentSize;
            Bitmap bmp = Autodesk.AutoCAD.ApplicationServices.DocumentExtension.CapturePreviewImage(doc, Convert.ToUInt32(size.Width), Convert.ToUInt32(size.Height));

            double vW = vtr.Width;
            double vH = vtr.Height;

            int bW = bmp.Width;
            int bH = bmp.Height;

            string path = Path + string.Format("{0}.png", filename);
            ed.WriteMessage(path);
            if (vH / vW < bH / bW)
            {
                vH = bW / vW * vH;
                vW = bW;


                if (IsPixelFormatIndexed(bmp.PixelFormat))
                {
                    Bitmap bmp1 = new Bitmap(Convert.ToInt32(vW), Convert.ToInt32(vH),
                        PixelFormat.Format32bppArgb);

                    using (Graphics g = Graphics.FromImage(bmp1))
                    {
                        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                        g.DrawImage(bmp, new Rectangle(0, 0, bmp1.Width, bmp1.Height),
                            new Rectangle(0, Convert.ToInt32(bH / 2 - vH / 2), Convert.ToInt32(vW), Convert.ToInt32(vH)), GraphicsUnit.Pixel);
                        g.Dispose();
                        //bmp1.Save("hh1.png", System.Drawing.Imaging.ImageFormat.Png);
                        bmp.Save(path);
                    }


                }
            }
            else
            {



                vW = bH / vH * vW;
                vH = bH;

                if (IsPixelFormatIndexed(bmp.PixelFormat))
                {
                    Bitmap bmp1 = new Bitmap(Convert.ToInt32(vW), Convert.ToInt32(vH),
                        PixelFormat.Format32bppArgb);

                    using (Graphics g = Graphics.FromImage(bmp1))
                    {
                        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                        g.DrawImage(bmp, new Rectangle(0, 0, bmp1.Width, bmp1.Height),
                            new Rectangle(Convert.ToInt32(bW / 2 - vW / 2), 0, Convert.ToInt32(vW), Convert.ToInt32(vH)), GraphicsUnit.Pixel);
                        g.Dispose();
                        //bmp1.Save("hh1.png", System.Drawing.Imaging.ImageFormat.Png);
                        bmp.Save(path);
                    }

                }

            }

        }