1 from ctypes import c_double, c_int, c_uint, POINTER

     2 from django.contrib.gis.geos.libgeos import lgeos, GEOM_PTR, CS_PTR

     3 from django.contrib.gis.geos.prototypes.errcheck import last_arg_byref, GEOSException

     4 

     5 ## Error-checking routines specific to coordinate sequences. ##

     6 def check_cs_ptr(result, func, cargs):

     7     "Error checking on routines that return Geometries."

     8     if not result:

     9         raise GEOSException('Error encountered checking Coordinate Sequence returned from GEOS C function "%s".' % func.__name__)

    10     return result

    11 

    12 def check_cs_op(result, func, cargs):

    13     "Checks the status code of a coordinate sequence operation."

    14     if result == 0:

    15         raise GEOSException('Could not set value on coordinate sequence')

    16     else:

    17         return result

    18 

    19 def check_cs_get(result, func, cargs):

    20     "Checking the coordinate sequence retrieval."

    21     check_cs_op(result, func, cargs)

    22     # Object in by reference, return its value.

    23     return last_arg_byref(cargs)

    24 

    25 ## Coordinate sequence prototype generation functions. ##

    26 def cs_int(func):

    27     "For coordinate sequence routines that return an integer."

    28     func.argtypes = [CS_PTR, POINTER(c_uint)]

    29     func.restype = c_int

    30     func.errcheck = check_cs_get

    31     return func

    32 

    33 def cs_operation(func, ordinate=False, get=False):

    34     "For coordinate sequence operations."

    35     if get:

    36         # Get routines get double parameter passed-in by reference.

    37         func.errcheck = check_cs_get

    38         dbl_param = POINTER(c_double)

    39     else:

    40         func.errcheck = check_cs_op

    41         dbl_param = c_double

    42 

    43     if ordinate:

    44         # Get/Set ordinate routines have an extra uint parameter.

    45         func.argtypes = [CS_PTR, c_uint, c_uint, dbl_param]

    46     else:

    47         func.argtypes = [CS_PTR, c_uint, dbl_param]

    48 

    49     func.restype = c_int

    50     return func

    51 

    52 def cs_output(func, argtypes):

    53     "For routines that return a coordinate sequence."

    54     func.argtypes = argtypes

    55     func.restype = CS_PTR

    56     func.errcheck = check_cs_ptr

    57     return func

    58 

    59 ## Coordinate Sequence ctypes prototypes ##

    60 

    61 # Coordinate Sequence constructors & cloning.

    62 cs_clone = cs_output(lgeos.GEOSCoordSeq_clone, [CS_PTR])

    63 create_cs = cs_output(lgeos.GEOSCoordSeq_create, [c_uint, c_uint])

    64 get_cs = cs_output(lgeos.GEOSGeom_getCoordSeq, [GEOM_PTR])

    65 

    66 # Getting, setting ordinate

    67 cs_getordinate = cs_operation(lgeos.GEOSCoordSeq_getOrdinate, ordinate=True, get=True)

    68 cs_setordinate = cs_operation(lgeos.GEOSCoordSeq_setOrdinate, ordinate=True)

    69 

    70 # For getting, x, y, z

    71 cs_getx = cs_operation(lgeos.GEOSCoordSeq_getX, get=True)

    72 cs_gety = cs_operation(lgeos.GEOSCoordSeq_getY, get=True)

    73 cs_getz = cs_operation(lgeos.GEOSCoordSeq_getZ, get=True)

    74 

    75 # For setting, x, y, z

    76 cs_setx = cs_operation(lgeos.GEOSCoordSeq_setX)

    77 cs_sety = cs_operation(lgeos.GEOSCoordSeq_setY)

    78 cs_setz = cs_operation(lgeos.GEOSCoordSeq_setZ)

    79 

    80 # These routines return size & dimensions.

    81 cs_getsize = cs_int(lgeos.GEOSCoordSeq_getSize)

    82 cs_getdims = cs_int(lgeos.GEOSCoordSeq_getDimensions)