Cython read large binary file using class definition

Question

My code tries to read a binary file using a Structure class:

import os
import mmap
from ctypes import Structure, c_uint

class StructFile(Structure):
    _pack_ = 1
    _fields_ = [('Xmin', c_uint),('Ymax', c_uint)]

fd = os.open(filePath, os.O_RDWR | os.O_BINARY)
mmap_file = mmap.mmap(fd, length=ln, access=mmap.ACCESS_WRITE, offset=0)
d_arrayFile = StructFile * numItems
data = d_arrayFile.from_buffer(mmap_file)
for i in data:
    print i.Xmin, i.Ymax

It works correctly, but I would like to speed it up using a cython class. The problem is when I use cdef class StructFile(Structure): the compilation says: "'Structure' is not a type name".

How could I do in order to cython recognise 'Structure' as a type name like 'int', 'object', etc.? Or any other solution to optimise the code (not using struct.unpack).

Thanks!