"""
This module contains functions that generate ctypes prototypes for the
GDAL routines.
"""
from ctypes import c_char_p,c_double,c_int,c_void_p
from django.contrib.gis.gdal.prototypes.errcheck import \
check_arg_errcode, check_errcode, check_geom, check_geom_offset, \
check_pointer, check_srs, check_str_arg, check_string, check_const_string
class gdal_char_p(c_char_p):
pass
def double_output(func, argtypes, errcheck=False, strarg=False):
"Generates a ctypes function that returns a double value."
func.argtypes = argtypes
func.restype = c_double
if errcheck: func.errcheck = check_arg_errcode
if strarg: func.errcheck = check_str_arg
return func
def geom_output(func, argtypes, offset=None):
"""
Generates a function that returns a Geometry either by reference
or directly (if the return_geom keyword is set to True).
"""
# Setting the argument types
func.argtypes = argtypes
if not offset:
# When a geometry pointer is directly returned.
func.restype = c_void_p
func.errcheck = check_geom
else:
# Error code returned, geometry is returned by-reference.
func.restype = c_int
def geomerrcheck(result, func, cargs):
return check_geom_offset(result, func, cargs, offset)
func.errcheck = geomerrcheck
return func
def int_output(func, argtypes):
"Generates a ctypes function that returns an integer value."
func.argtypes = argtypes
func.restype = c_int
return func
def srs_output(func, argtypes):
"""
Generates a ctypes prototype for the given function with
the given C arguments that returns a pointer to an OGR
Spatial Reference System.
"""
func.argtypes = argtypes
func.restype = c_void_p
func.errcheck = check_srs
return func
def const_string_output(func, argtypes, offset=None):
func.argtypes = argtypes
if offset:
func.restype = c_int
else:
func.restype = c_char_p
def _check_const(result, func, cargs):
return check_const_string(result, func, cargs, offset=offset)
func.errcheck = _check_const
return func
def string_output(func, argtypes, offset=-1, str_result=False):
"""
Generates a ctypes prototype for the given function with the
given argument types that returns a string from a GDAL pointer.
The `const` flag indicates whether the allocated pointer should
be freed via the GDAL library routine VSIFree -- but only applies
only when `str_result` is True.
"""
func.argtypes = argtypes
if str_result:
# Use subclass of c_char_p so the error checking routine
# can free the memory at the pointer's address.
func.restype = gdal_char_p
else:
# Error code is returned
func.restype = c_int
# Dynamically defining our error-checking function with the
# given offset.
def _check_str(result, func, cargs):
return check_string(result, func, cargs,
offset=offset, str_result=str_result)
func.errcheck = _check_str
return func
def void_output(func, argtypes, errcheck=True):
"""
For functions that don't only return an error code that needs to
be examined.
"""
if argtypes: func.argtypes = argtypes
if errcheck:
# `errcheck` keyword may be set to False for routines that
# return void, rather than a status code.
func.restype = c_int
func.errcheck = check_errcode
else:
func.restype = None
return func
def voidptr_output(func, argtypes):
"For functions that return c_void_p."
func.argtypes = argtypes
func.restype = c_void_p
func.errcheck = check_pointer
return func
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