/django/contrib/gis/geos/prototypes/coordseq.py

 1from ctypes import c_double, c_int, c_uint, POINTER
 2from django.contrib.gis.geos.libgeos import GEOM_PTR, CS_PTR
 3from django.contrib.gis.geos.prototypes.errcheck import last_arg_byref, GEOSException
 4from django.contrib.gis.geos.prototypes.threadsafe import GEOSFunc
 5
 6## Error-checking routines specific to coordinate sequences. ##
 7def check_cs_ptr(result, func, cargs):
 8    "Error checking on routines that return Geometries."
 9    if not result:
10        raise GEOSException('Error encountered checking Coordinate Sequence returned from GEOS C function "%s".' % func.__name__)
11    return result
12
13def check_cs_op(result, func, cargs):
14    "Checks the status code of a coordinate sequence operation."
15    if result == 0:
16        raise GEOSException('Could not set value on coordinate sequence')
17    else:
18        return result
19
20def check_cs_get(result, func, cargs):
21    "Checking the coordinate sequence retrieval."
22    check_cs_op(result, func, cargs)
23    # Object in by reference, return its value.
24    return last_arg_byref(cargs)
25
26## Coordinate sequence prototype generation functions. ##
27def cs_int(func):
28    "For coordinate sequence routines that return an integer."
29    func.argtypes = [CS_PTR, POINTER(c_uint)]
30    func.restype = c_int
31    func.errcheck = check_cs_get
32    return func
33
34def cs_operation(func, ordinate=False, get=False):
35    "For coordinate sequence operations."
36    if get:
37        # Get routines get double parameter passed-in by reference.
38        func.errcheck = check_cs_get
39        dbl_param = POINTER(c_double)
40    else:
41        func.errcheck = check_cs_op
42        dbl_param = c_double
43
44    if ordinate:
45        # Get/Set ordinate routines have an extra uint parameter.
46        func.argtypes = [CS_PTR, c_uint, c_uint, dbl_param]
47    else:
48        func.argtypes = [CS_PTR, c_uint, dbl_param]
49
50    func.restype = c_int
51    return func
52
53def cs_output(func, argtypes):
54    "For routines that return a coordinate sequence."
55    func.argtypes = argtypes
56    func.restype = CS_PTR
57    func.errcheck = check_cs_ptr
58    return func
59
60## Coordinate Sequence ctypes prototypes ##
61
62# Coordinate Sequence constructors & cloning.
63cs_clone = cs_output(GEOSFunc('GEOSCoordSeq_clone'), [CS_PTR])
64create_cs = cs_output(GEOSFunc('GEOSCoordSeq_create'), [c_uint, c_uint])
65get_cs = cs_output(GEOSFunc('GEOSGeom_getCoordSeq'), [GEOM_PTR])
66
67# Getting, setting ordinate
68cs_getordinate = cs_operation(GEOSFunc('GEOSCoordSeq_getOrdinate'), ordinate=True, get=True)
69cs_setordinate = cs_operation(GEOSFunc('GEOSCoordSeq_setOrdinate'), ordinate=True)
70
71# For getting, x, y, z
72cs_getx = cs_operation(GEOSFunc('GEOSCoordSeq_getX'), get=True)
73cs_gety = cs_operation(GEOSFunc('GEOSCoordSeq_getY'), get=True)
74cs_getz = cs_operation(GEOSFunc('GEOSCoordSeq_getZ'), get=True)
75
76# For setting, x, y, z
77cs_setx = cs_operation(GEOSFunc('GEOSCoordSeq_setX'))
78cs_sety = cs_operation(GEOSFunc('GEOSCoordSeq_setY'))
79cs_setz = cs_operation(GEOSFunc('GEOSCoordSeq_setZ'))
80
81# These routines return size & dimensions.
82cs_getsize = cs_int(GEOSFunc('GEOSCoordSeq_getSize'))
83cs_getdims = cs_int(GEOSFunc('GEOSCoordSeq_getDimensions'))