Code source de 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
@classmethod
[docs] 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)
