"""
This module houses the Geometry Collection objects:
GeometryCollection, MultiPoint, MultiLineString, and MultiPolygon
"""
from ctypes import c_int,c_uint,byref
from django.contrib.gis.geos.error import GEOSException,GEOSIndexError
from django.contrib.gis.geos.geometry import GEOSGeometry
from django.contrib.gis.geos.libgeos import get_pointer_arr,GEOM_PTR,GEOS_PREPARE
from django.contrib.gis.geos.linestring import LineString,LinearRing
from django.contrib.gis.geos.point import Point
from django.contrib.gis.geos.polygon import Polygon
from django.contrib.gis.geos import prototypes
class GeometryCollection(GEOSGeometry):
_typeid = 7
def __init__(self, *args, **kwargs):
"Initializes a Geometry Collection from a sequence of Geometry objects."
# Checking the arguments
if not args:
raise TypeError('Must provide at least one Geometry to initialize %s.' % self.__class__.__name__)
if len(args) == 1:
# If only one geometry provided or a list of geometries is provided
# in the first argument.
if isinstance(args[0], (tuple, list)):
init_geoms = args[0]
else:
init_geoms = args
else:
init_geoms = args
# Ensuring that only the permitted geometries are allowed in this collection
# this is moved to list mixin super class
self._check_allowed(init_geoms)
# Creating the geometry pointer array.
collection = self._create_collection(len(init_geoms), iter(init_geoms))
super(GeometryCollection, self).__init__(collection, **kwargs)
def __iter__(self):
"Iterates over each Geometry in the Collection."
for i in xrange(len(self)):
yield self[i]
def __len__(self):
"Returns the number of geometries in this Collection."
return self.num_geom
### Methods for compatibility with ListMixin ###
def _create_collection(self, length, items):
# Creating the geometry pointer array.
geoms = get_pointer_arr(length)
for i, g in enumerate(items):
# this is a little sloppy, but makes life easier
# allow GEOSGeometry types (python wrappers) or pointer types
geoms[i] = capi.geom_clone(getattr(g, 'ptr', g))
return capi.create_collection(c_int(self._typeid), byref(geoms), c_uint(length))
def _get_single_internal(self, index):
return capi.get_geomn(self.ptr, index)
def _get_single_external(self, index):
"Returns the Geometry from this Collection at the given index (0-based)."
# Checking the index and returning the corresponding GEOS geometry.
return GEOSGeometry(capi.geom_clone(self._get_single_internal(index)), srid=self.srid)
def _set_list(self, length, items):
"Create a new collection, and destroy the contents of the previous pointer."
prev_ptr = self.ptr
srid = self.srid
self.ptr = self._create_collection(length, items)
if srid: self.srid = srid
capi.destroy_geom(prev_ptr)
_set_single = GEOSGeometry._set_single_rebuild
_assign_extended_slice = GEOSGeometry._assign_extended_slice_rebuild
@property
def kml(self):
"Returns the KML for this Geometry Collection."
return '<MultiGeometry>%s</MultiGeometry>' % ''.join([g.kml for g in self])
@property
def tuple(self):
"Returns a tuple of all the coordinates in this Geometry Collection"
return tuple([g.tuple for g in self])
coords = tuple
# MultiPoint, MultiLineString, and MultiPolygon class definitions.
class MultiPoint(GeometryCollection):
_allowed = Point
_typeid = 4
class MultiLineString(GeometryCollection):
_allowed = (LineString, LinearRing)
_typeid = 5
@property
def merged(self):
"""
Returns a LineString representing the line merge of this
MultiLineString.
"""
return self._topology(capi.geos_linemerge(self.ptr))
class MultiPolygon(GeometryCollection):
_allowed = Polygon
_typeid = 6
@property
def cascaded_union(self):
"Returns a cascaded union of this MultiPolygon."
if GEOS_PREPARE:
return GEOSGeometry(capi.geos_cascaded_union(self.ptr), self.srid)
else:
raise GEOSException('The cascaded union operation requires GEOS 3.1+.')
# Setting the allowed types here since GeometryCollection is defined before
# its subclasses.
GeometryCollection._allowed = (Point, LineString, LinearRing, Polygon, MultiPoint, MultiLineString, MultiPolygon)
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