+
−"""
+
− This module houses the Geometry Collection objects:
+
− GeometryCollection, MultiPoint, MultiLineString, and MultiPolygon
+
−"""
+
−from ctypes import c_int, c_uint, byref
+
−from types import TupleType, ListType
+
−from django.contrib.gis.geos.base import GEOSGeometry
+
−from django.contrib.gis.geos.error import GEOSException, GEOSIndexError
+
−from django.contrib.gis.geos.geometries import Point, LineString, LinearRing, Polygon
+
−from django.contrib.gis.geos.libgeos import get_pointer_arr, GEOM_PTR
+
−from django.contrib.gis.geos.prototypes import create_collection, destroy_geom, geom_clone, geos_typeid, get_cs, get_geomn
+
−
+
−class GeometryCollection(GEOSGeometry):
+
−    _allowed = (Point, LineString, LinearRing, Polygon)
+
−    _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], (TupleType, ListType)):
+
−                init_geoms = args[0]
+
−            else:
+
−                init_geoms = args
+
−        else:
+
−            init_geoms = args
+
−
+
−        # Ensuring that only the permitted geometries are allowed in this collection
+
−        if False in [isinstance(geom, self._allowed) for geom in init_geoms]:
+
−            raise TypeError('Invalid Geometry type encountered in the arguments.')
+
−
+
−        # Creating the geometry pointer array.
+
−        ngeoms = len(init_geoms)
+
−        geoms = get_pointer_arr(ngeoms)
+
−        for i in xrange(ngeoms): geoms[i] = geom_clone(init_geoms[i].ptr)
+
−        super(GeometryCollection, self).__init__(create_collection(c_int(self._typeid), byref(geoms), c_uint(ngeoms)), **kwargs)
+
−
+
−    def __getitem__(self, index):
+
−        "Returns the Geometry from this Collection at the given index (0-based)."
+
−        # Checking the index and returning the corresponding GEOS geometry.
+
−        self._checkindex(index)
+
−        return GEOSGeometry(geom_clone(get_geomn(self.ptr, index)), srid=self.srid)
+
−
+
−    def __setitem__(self, index, geom):
+
−        "Sets the Geometry at the specified index."
+
−        self._checkindex(index)
+
−        if not isinstance(geom, self._allowed):
+
−            raise TypeError('Incompatible Geometry for collection.')
+
−        
+
−        ngeoms = len(self)
+
−        geoms = get_pointer_arr(ngeoms)
+
−        for i in xrange(ngeoms):
+
−            if i == index:
+
−                geoms[i] = geom_clone(geom.ptr)
+
−            else:
+
−                geoms[i] = geom_clone(get_geomn(self.ptr, i))
+
−        
+
−        # Creating a new collection, and destroying the contents of the previous poiner.
+
−        prev_ptr = self.ptr
+
−        srid = self.srid
+
−        self._ptr = create_collection(c_int(self._typeid), byref(geoms), c_uint(ngeoms))
+
−        if srid: self.srid = srid
+
−        destroy_geom(prev_ptr)
+
−
+
−    def __iter__(self):
+
−        "Iterates over each Geometry in the Collection."
+
−        for i in xrange(len(self)):
+
−            yield self.__getitem__(i)
+
−
+
−    def __len__(self):
+
−        "Returns the number of geometries in this Collection."
+
−        return self.num_geom
+
−
+
−    def _checkindex(self, index):
+
−        "Checks the given geometry index."
+
−        if index < 0 or index >= self.num_geom:
+
−            raise GEOSIndexError('invalid GEOS Geometry index: %s' % str(index))
+
−
+
−    @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
+
−class MultiPolygon(GeometryCollection): 
+
−    _allowed = Polygon
+
−    _typeid = 6