projects.mako.cc - wikipedia-api-cdsw/blob - win_unicode_console/buffer.py

   1
   2 from ctypes import (byref, POINTER, Structure, pythonapi,
   3         c_int, c_char, c_char_p, c_void_p, py_object, c_ssize_t)
   4 import sys
   5
   6 c_ssize_p = POINTER(c_ssize_t)
   7
   8 PyObject_GetBuffer = pythonapi.PyObject_GetBuffer
   9 PyBuffer_Release = pythonapi.PyBuffer_Release
  10
  11
  12 PyBUF_SIMPLE = 0
  13 PyBUF_WRITABLE = 1
  14
  15
  16 class Py_buffer(Structure):
  17         _fields_ = [
  18                 ("buf", c_void_p),
  19                 ("obj", py_object),
  20                 ("len", c_ssize_t),
  21                 ("itemsize", c_ssize_t),
  22                 ("readonly", c_int),
  23                 ("ndim", c_int),
  24                 ("format", c_char_p),
  25                 ("shape", c_ssize_p),
  26                 ("strides", c_ssize_p),
  27                 ("suboffsets", c_ssize_p),
  28                 ("internal", c_void_p)
  29         ]
  30
  31         if sys.version_info[0] < 3:
  32                 _fields_.insert(-1, ("smalltable", c_ssize_t * 2))
  33
  34         @classmethod
  35         def get_from(cls, obj, flags=PyBUF_SIMPLE):
  36                 buf = cls()
  37                 PyObject_GetBuffer(py_object(obj), byref(buf), flags)
  38                 return buf
  39
  40         def release(self):
  41                 PyBuffer_Release(byref(self))
  42
  43
  44 def get_buffer(obj, writable=False):
  45         buf = Py_buffer.get_from(obj, PyBUF_WRITABLE if writable else PyBUF_SIMPLE)
  46         try:
  47                 buffer_type = c_char * buf.len
  48                 return buffer_type.from_address(buf.buf)
  49         finally:
  50                 buf.release()
  51