Zoom cad居中显示图形 快速缩放方法

跟命令行输入 “zoom”  空格 “ e ” 相比，此方法无动态缩放过程，速度更快。效果如下：

 public static void 快速居中()
 {
     var view = Z.ed.GetCurrentView();
     double xxx = (Z.db.Extmin.X + Z.db.Extmax.X) / 2  ;
     double yyy = (Z.db.Extmin.Y + Z.db.Extmax.Y) / 2;
     view .CenterPoint = new Point2d(xxx,yyy);
     view.Height = Z.db.Extmax.Y - Z.db.Extmin.Y;
     view.Width = Z.db.Extmax.X - Z.db.Extmin.X;
     Z.ed.SetCurrentView(view);
 }

public static class EditorExtension
    {
        public static void Zoom(this Editor ed, Extents3d ext)
        {
            if (ed == null)
                throw new ArgumentNullException("ed");
            using (ViewTableRecord view = ed.GetCurrentView())
            {
                Matrix3d worldToEye = Matrix3d.WorldToPlane(view.ViewDirection) *
                    Matrix3d.Displacement(Point3d.Origin - view.Target) *
                    Matrix3d.Rotation(view.ViewTwist, view.ViewDirection, view.Target);
                ext.TransformBy(worldToEye);
                view.Width = ext.MaxPoint.X - ext.MinPoint.X;
                view.Height = ext.MaxPoint.Y - ext.MinPoint.Y;
                view.CenterPoint = new Point2d(
                    (ext.MaxPoint.X + ext.MinPoint.X) / 2.0,
                    (ext.MaxPoint.Y + ext.MinPoint.Y) / 2.0);
                ed.SetCurrentView(view);
            }
        }

        public static void ZoomExtents(this Editor ed)
        {
            Database db = ed.Document.Database;
            db.UpdateExt(false);
            Extents3d ext = (short)Application.GetSystemVariable("cvport") == 1 ?
                new Extents3d(db.Pextmin, db.Pextmax) :
                new Extents3d(db.Extmin, db.Extmax);
            ed.Zoom(ext);
        }
    }