利用linq获取在两点确定的矩形内的块参照 

Query syntax:

private ObjectId[] FindBlockReferencesInRectangle(Point3d pt1, Point3d pt2, Database db)        {            using (Transaction tr = db.TransactionManager.StartOpenCloseTransaction())            using (Line line = new Line(pt1, pt2))            {                Extents3d bound = line.GeometricExtents;                BlockTableRecord modelSpace = (BlockTableRecord)tr.GetObject(                  SymbolUtilityServices.GetBlockModelSpaceId(db), OpenMode.ForRead);                Func
      
        isBlockReference = (id =>                    id.ObjectClass == RXClass.GetClass(typeof(BlockReference)));                Func
       
         isInside = (id =>                {                    BlockReference br = (BlockReference)tr.GetObject(id, OpenMode.ForRead);                    Extents3d exts = new Extents3d(bound.MinPoint, bound.MaxPoint);                    exts.AddExtents(br.GeometricExtents);                    return bound.IsEqualTo(exts);                }); ;                var blocks =                    from ObjectId id in modelSpace                    where isBlockReference(id) && isInside(id)                    select id;                return blocks.ToArray();            }        }
       
      

Extension methods syntax:

private ObjectId[] FindBlockReferencesInRectangle(Point3d pt1, Point3d pt2, Database db)        {            using (Transaction tr = db.TransactionManager.StartOpenCloseTransaction())            using (Line line = new Line(pt1, pt2))            {                Extents3d bound = line.GeometricExtents;                BlockTableRecord modelSpace = (BlockTableRecord)tr.GetObject(                    SymbolUtilityServices.GetBlockModelSpaceId(db), OpenMode.ForRead);                Func
      
        isBlockReference = (id =>                    id.ObjectClass == RXClass.GetClass(typeof(BlockReference)));                Func
       
         isInside = (id =>                {                    BlockReference br = (BlockReference)tr.GetObject(id, OpenMode.ForRead);                    Extents3d exts = new Extents3d(bound.MinPoint, bound.MaxPoint);                    exts.AddExtents(br.GeometricExtents);                    return bound.IsEqualTo(exts);                });                return modelSpace                    .Cast
        
         ()                    .Where(isBlockReference)                    .Where(isInside)                    .ToArray();            }        }