• 1.9
  • dev
  • Documentation version: 1.10

Source code for django.contrib.gis.geos.polygon

from ctypes import byref, c_uint

from django.contrib.gis.geos import prototypes as capi
from django.contrib.gis.geos.geometry import GEOSGeometry
from django.contrib.gis.geos.libgeos import GEOM_PTR, get_pointer_arr
from django.contrib.gis.geos.linestring import LinearRing
from django.utils import six
from django.utils.six.moves import range

[docs]class Polygon(GEOSGeometry): _minlength = 1 def __init__(self, *args, **kwargs): """ Initializes on an exterior ring and a sequence of holes (both instances may be either LinearRing instances, or a tuple/list that may be constructed into a LinearRing). Examples of initialization, where shell, hole1, and hole2 are valid LinearRing geometries: >>> from django.contrib.gis.geos import LinearRing, Polygon >>> shell = hole1 = hole2 = LinearRing() >>> poly = Polygon(shell, hole1, hole2) >>> poly = Polygon(shell, (hole1, hole2)) >>> # Example where a tuple parameters are used: >>> poly = Polygon(((0, 0), (0, 10), (10, 10), (0, 10), (0, 0)), ... ((4, 4), (4, 6), (6, 6), (6, 4), (4, 4))) """ if not args: super(Polygon, self).__init__(self._create_polygon(0, None), **kwargs) return # Getting the ext_ring and init_holes parameters from the argument list ext_ring = args[0] init_holes = args[1:] n_holes = len(init_holes) # If initialized as Polygon(shell, (LinearRing, LinearRing)) [for backward-compatibility] if n_holes == 1 and isinstance(init_holes[0], (tuple, list)): if len(init_holes[0]) == 0: init_holes = () n_holes = 0 elif isinstance(init_holes[0][0], LinearRing): init_holes = init_holes[0] n_holes = len(init_holes) polygon = self._create_polygon(n_holes + 1, (ext_ring,) + init_holes) super(Polygon, self).__init__(polygon, **kwargs) def __iter__(self): "Iterates over each ring in the polygon." for i in range(len(self)): yield self[i] def __len__(self): "Returns the number of rings in this Polygon." return self.num_interior_rings + 1
[docs] @classmethod def from_bbox(cls, bbox): "Constructs a Polygon from a bounding box (4-tuple)." x0, y0, x1, y1 = bbox for z in bbox: if not isinstance(z, six.integer_types + (float,)): return GEOSGeometry('POLYGON((%s %s, %s %s, %s %s, %s %s, %s %s))' % (x0, y0, x0, y1, x1, y1, x1, y0, x0, y0)) return Polygon(((x0, y0), (x0, y1), (x1, y1), (x1, y0), (x0, y0)))
# ### These routines are needed for list-like operation w/ListMixin ### def _create_polygon(self, length, items): # Instantiate LinearRing objects if necessary, but don't clone them yet # _construct_ring will throw a TypeError if a parameter isn't a valid ring # If we cloned the pointers here, we wouldn't be able to clean up # in case of error. if not length: return capi.create_empty_polygon() rings = [] for r in items: if isinstance(r, GEOM_PTR): rings.append(r) else: rings.append(self._construct_ring(r)) shell = self._clone(rings.pop(0)) n_holes = length - 1 if n_holes: holes = get_pointer_arr(n_holes) for i, r in enumerate(rings): holes[i] = self._clone(r) holes_param = byref(holes) else: holes_param = None return capi.create_polygon(shell, holes_param, c_uint(n_holes)) def _clone(self, g): if isinstance(g, GEOM_PTR): return capi.geom_clone(g) else: return capi.geom_clone(g.ptr) def _construct_ring(self, param, msg=( 'Parameter must be a sequence of LinearRings or objects that can initialize to LinearRings')): "Helper routine for trying to construct a ring from the given parameter." if isinstance(param, LinearRing): return param try: ring = LinearRing(param) return ring except TypeError: raise TypeError(msg) def _set_list(self, length, items): # Getting the current pointer, replacing with the newly constructed # geometry, and destroying the old geometry. prev_ptr = self.ptr srid = self.srid self.ptr = self._create_polygon(length, items) if srid: self.srid = srid capi.destroy_geom(prev_ptr) def _get_single_internal(self, index): """ Returns the ring at the specified index. The first index, 0, will always return the exterior ring. Indices > 0 will return the interior ring at the given index (e.g., poly[1] and poly[2] would return the first and second interior ring, respectively). CAREFUL: Internal/External are not the same as Interior/Exterior! _get_single_internal returns a pointer from the existing geometries for use internally by the object's methods. _get_single_external returns a clone of the same geometry for use by external code. """ if index == 0: return capi.get_extring(self.ptr) else: # Getting the interior ring, have to subtract 1 from the index. return capi.get_intring(self.ptr, index - 1) def _get_single_external(self, index): return GEOSGeometry(capi.geom_clone(self._get_single_internal(index)), srid=self.srid) _set_single = GEOSGeometry._set_single_rebuild _assign_extended_slice = GEOSGeometry._assign_extended_slice_rebuild # #### Polygon Properties #### @property def num_interior_rings(self): "Returns the number of interior rings." # Getting the number of rings return capi.get_nrings(self.ptr) def _get_ext_ring(self): "Gets the exterior ring of the Polygon." return self[0] def _set_ext_ring(self, ring): "Sets the exterior ring of the Polygon." self[0] = ring # Properties for the exterior ring/shell. exterior_ring = property(_get_ext_ring, _set_ext_ring) shell = exterior_ring @property def tuple(self): "Gets the tuple for each ring in this Polygon." return tuple(self[i].tuple for i in range(len(self))) coords = tuple @property def kml(self): "Returns the KML representation of this Polygon." inner_kml = ''.join( "<innerBoundaryIs>%s</innerBoundaryIs>" % self[i + 1].kml for i in range(self.num_interior_rings) ) return "<Polygon><outerBoundaryIs>%s</outerBoundaryIs>%s</Polygon>" % (self[0].kml, inner_kml)
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