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