--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/gis/geos/base.py Tue Oct 14 16:00:59 2008 +0000
@@ -0,0 +1,608 @@
+"""
+ This module contains the 'base' GEOSGeometry object -- all GEOS Geometries
+ inherit from this object.
+"""
+# Python, ctypes and types dependencies.
+import re
+from ctypes import addressof, byref, c_double, c_size_t
+from types import UnicodeType
+
+# GEOS-related dependencies.
+from django.contrib.gis.geos.coordseq import GEOSCoordSeq
+from django.contrib.gis.geos.error import GEOSException
+from django.contrib.gis.geos.libgeos import GEOM_PTR
+
+# All other functions in this module come from the ctypes
+# prototypes module -- which handles all interaction with
+# the underlying GEOS library.
+from django.contrib.gis.geos.prototypes import *
+
+# Trying to import GDAL libraries, if available. Have to place in
+# try/except since this package may be used outside GeoDjango.
+try:
+ from django.contrib.gis.gdal import OGRGeometry, SpatialReference, GEOJSON
+ HAS_GDAL = True
+except:
+ HAS_GDAL, GEOJSON = False, False
+
+# Regular expression for recognizing HEXEWKB and WKT. A prophylactic measure
+# to prevent potentially malicious input from reaching the underlying C
+# library. Not a substitute for good web security programming practices.
+hex_regex = re.compile(r'^[0-9A-F]+$', re.I)
+wkt_regex = re.compile(r'^(SRID=(?P<srid>\d+);)?(?P<wkt>(POINT|LINESTRING|LINEARRING|POLYGON|MULTIPOINT|MULTILINESTRING|MULTIPOLYGON|GEOMETRYCOLLECTION)[ACEGIMLONPSRUTY\d,\.\-\(\) ]+)$', re.I)
+json_regex = re.compile(r'^\{.+\}$')
+
+class GEOSGeometry(object):
+ "A class that, generally, encapsulates a GEOS geometry."
+
+ # Initially, the geometry pointer is NULL
+ _ptr = None
+
+ #### Python 'magic' routines ####
+ def __init__(self, geo_input, srid=None):
+ """
+ The base constructor for GEOS geometry objects, and may take the
+ following inputs:
+
+ * string: WKT
+ * string: HEXEWKB (a PostGIS-specific canonical form)
+ * buffer: WKB
+
+ The `srid` keyword is used to specify the Source Reference Identifier
+ (SRID) number for this Geometry. If not set, the SRID will be None.
+ """
+ if isinstance(geo_input, basestring):
+ if isinstance(geo_input, UnicodeType):
+ # Encoding to ASCII, WKT or HEXEWKB doesn't need any more.
+ geo_input = geo_input.encode('ascii')
+
+ wkt_m = wkt_regex.match(geo_input)
+ if wkt_m:
+ # Handling WKT input.
+ if wkt_m.group('srid'): srid = int(wkt_m.group('srid'))
+ g = from_wkt(wkt_m.group('wkt'))
+ elif hex_regex.match(geo_input):
+ # Handling HEXEWKB input.
+ g = from_hex(geo_input, len(geo_input))
+ elif GEOJSON and json_regex.match(geo_input):
+ # Handling GeoJSON input.
+ wkb_input = str(OGRGeometry(geo_input).wkb)
+ g = from_wkb(wkb_input, len(wkb_input))
+ else:
+ raise ValueError('String or unicode input unrecognized as WKT EWKT, and HEXEWKB.')
+ elif isinstance(geo_input, GEOM_PTR):
+ # When the input is a pointer to a geomtry (GEOM_PTR).
+ g = geo_input
+ elif isinstance(geo_input, buffer):
+ # When the input is a buffer (WKB).
+ wkb_input = str(geo_input)
+ g = from_wkb(wkb_input, len(wkb_input))
+ else:
+ # Invalid geometry type.
+ raise TypeError('Improper geometry input type: %s' % str(type(geo_input)))
+
+ if bool(g):
+ # Setting the pointer object with a valid pointer.
+ self._ptr = g
+ else:
+ raise GEOSException('Could not initialize GEOS Geometry with given input.')
+
+ # Post-initialization setup.
+ self._post_init(srid)
+
+ def _post_init(self, srid):
+ "Helper routine for performing post-initialization setup."
+ # Setting the SRID, if given.
+ if srid and isinstance(srid, int): self.srid = srid
+
+ # Setting the class type (e.g., Point, Polygon, etc.)
+ self.__class__ = GEOS_CLASSES[self.geom_typeid]
+
+ # Setting the coordinate sequence for the geometry (will be None on
+ # geometries that do not have coordinate sequences)
+ self._set_cs()
+
+ @property
+ def ptr(self):
+ """
+ Property for controlling access to the GEOS geometry pointer. Using
+ this raises an exception when the pointer is NULL, thus preventing
+ the C library from attempting to access an invalid memory location.
+ """
+ if self._ptr:
+ return self._ptr
+ else:
+ raise GEOSException('NULL GEOS pointer encountered; was this geometry modified?')
+
+ def __del__(self):
+ """
+ Destroys this Geometry; in other words, frees the memory used by the
+ GEOS C++ object.
+ """
+ if self._ptr: destroy_geom(self._ptr)
+
+ def __copy__(self):
+ """
+ Returns a clone because the copy of a GEOSGeometry may contain an
+ invalid pointer location if the original is garbage collected.
+ """
+ return self.clone()
+
+ def __deepcopy__(self, memodict):
+ """
+ The `deepcopy` routine is used by the `Node` class of django.utils.tree;
+ thus, the protocol routine needs to be implemented to return correct
+ copies (clones) of these GEOS objects, which use C pointers.
+ """
+ return self.clone()
+
+ def __str__(self):
+ "WKT is used for the string representation."
+ return self.wkt
+
+ def __repr__(self):
+ "Short-hand representation because WKT may be very large."
+ return '<%s object at %s>' % (self.geom_type, hex(addressof(self.ptr)))
+
+ # Pickling support
+ def __getstate__(self):
+ # The pickled state is simply a tuple of the WKB (in string form)
+ # and the SRID.
+ return str(self.wkb), self.srid
+
+ def __setstate__(self, state):
+ # Instantiating from the tuple state that was pickled.
+ wkb, srid = state
+ ptr = from_wkb(wkb, len(wkb))
+ if not ptr: raise GEOSException('Invalid Geometry loaded from pickled state.')
+ self._ptr = ptr
+ self._post_init(srid)
+
+ # Comparison operators
+ def __eq__(self, other):
+ """
+ Equivalence testing, a Geometry may be compared with another Geometry
+ or a WKT representation.
+ """
+ if isinstance(other, basestring):
+ return self.wkt == other
+ elif isinstance(other, GEOSGeometry):
+ return self.equals_exact(other)
+ else:
+ return False
+
+ def __ne__(self, other):
+ "The not equals operator."
+ return not (self == other)
+
+ ### Geometry set-like operations ###
+ # Thanks to Sean Gillies for inspiration:
+ # http://lists.gispython.org/pipermail/community/2007-July/001034.html
+ # g = g1 | g2
+ def __or__(self, other):
+ "Returns the union of this Geometry and the other."
+ return self.union(other)
+
+ # g = g1 & g2
+ def __and__(self, other):
+ "Returns the intersection of this Geometry and the other."
+ return self.intersection(other)
+
+ # g = g1 - g2
+ def __sub__(self, other):
+ "Return the difference this Geometry and the other."
+ return self.difference(other)
+
+ # g = g1 ^ g2
+ def __xor__(self, other):
+ "Return the symmetric difference of this Geometry and the other."
+ return self.sym_difference(other)
+
+ #### Coordinate Sequence Routines ####
+ @property
+ def has_cs(self):
+ "Returns True if this Geometry has a coordinate sequence, False if not."
+ # Only these geometries are allowed to have coordinate sequences.
+ if isinstance(self, (Point, LineString, LinearRing)):
+ return True
+ else:
+ return False
+
+ def _set_cs(self):
+ "Sets the coordinate sequence for this Geometry."
+ if self.has_cs:
+ self._cs = GEOSCoordSeq(get_cs(self.ptr), self.hasz)
+ else:
+ self._cs = None
+
+ @property
+ def coord_seq(self):
+ "Returns a clone of the coordinate sequence for this Geometry."
+ if self.has_cs:
+ return self._cs.clone()
+
+ #### Geometry Info ####
+ @property
+ def geom_type(self):
+ "Returns a string representing the Geometry type, e.g. 'Polygon'"
+ return geos_type(self.ptr)
+
+ @property
+ def geom_typeid(self):
+ "Returns an integer representing the Geometry type."
+ return geos_typeid(self.ptr)
+
+ @property
+ def num_geom(self):
+ "Returns the number of geometries in the Geometry."
+ return get_num_geoms(self.ptr)
+
+ @property
+ def num_coords(self):
+ "Returns the number of coordinates in the Geometry."
+ return get_num_coords(self.ptr)
+
+ @property
+ def num_points(self):
+ "Returns the number points, or coordinates, in the Geometry."
+ return self.num_coords
+
+ @property
+ def dims(self):
+ "Returns the dimension of this Geometry (0=point, 1=line, 2=surface)."
+ return get_dims(self.ptr)
+
+ def normalize(self):
+ "Converts this Geometry to normal form (or canonical form)."
+ return geos_normalize(self.ptr)
+
+ #### Unary predicates ####
+ @property
+ def empty(self):
+ """
+ Returns a boolean indicating whether the set of points in this Geometry
+ are empty.
+ """
+ return geos_isempty(self.ptr)
+
+ @property
+ def hasz(self):
+ "Returns whether the geometry has a 3D dimension."
+ return geos_hasz(self.ptr)
+
+ @property
+ def ring(self):
+ "Returns whether or not the geometry is a ring."
+ return geos_isring(self.ptr)
+
+ @property
+ def simple(self):
+ "Returns false if the Geometry not simple."
+ return geos_issimple(self.ptr)
+
+ @property
+ def valid(self):
+ "This property tests the validity of this Geometry."
+ return geos_isvalid(self.ptr)
+
+ #### Binary predicates. ####
+ def contains(self, other):
+ "Returns true if other.within(this) returns true."
+ return geos_contains(self.ptr, other.ptr)
+
+ def crosses(self, other):
+ """
+ Returns true if the DE-9IM intersection matrix for the two Geometries
+ is T*T****** (for a point and a curve,a point and an area or a line and
+ an area) 0******** (for two curves).
+ """
+ return geos_crosses(self.ptr, other.ptr)
+
+ def disjoint(self, other):
+ """
+ Returns true if the DE-9IM intersection matrix for the two Geometries
+ is FF*FF****.
+ """
+ return geos_disjoint(self.ptr, other.ptr)
+
+ def equals(self, other):
+ """
+ Returns true if the DE-9IM intersection matrix for the two Geometries
+ is T*F**FFF*.
+ """
+ return geos_equals(self.ptr, other.ptr)
+
+ def equals_exact(self, other, tolerance=0):
+ """
+ Returns true if the two Geometries are exactly equal, up to a
+ specified tolerance.
+ """
+ return geos_equalsexact(self.ptr, other.ptr, float(tolerance))
+
+ def intersects(self, other):
+ "Returns true if disjoint returns false."
+ return geos_intersects(self.ptr, other.ptr)
+
+ def overlaps(self, other):
+ """
+ Returns true if the DE-9IM intersection matrix for the two Geometries
+ is T*T***T** (for two points or two surfaces) 1*T***T** (for two curves).
+ """
+ return geos_overlaps(self.ptr, other.ptr)
+
+ def relate_pattern(self, other, pattern):
+ """
+ Returns true if the elements in the DE-9IM intersection matrix for the
+ two Geometries match the elements in pattern.
+ """
+ if not isinstance(pattern, str) or len(pattern) > 9:
+ raise GEOSException('invalid intersection matrix pattern')
+ return geos_relatepattern(self.ptr, other.ptr, pattern)
+
+ def touches(self, other):
+ """
+ Returns true if the DE-9IM intersection matrix for the two Geometries
+ is FT*******, F**T***** or F***T****.
+ """
+ return geos_touches(self.ptr, other.ptr)
+
+ def within(self, other):
+ """
+ Returns true if the DE-9IM intersection matrix for the two Geometries
+ is T*F**F***.
+ """
+ return geos_within(self.ptr, other.ptr)
+
+ #### SRID Routines ####
+ def get_srid(self):
+ "Gets the SRID for the geometry, returns None if no SRID is set."
+ s = geos_get_srid(self.ptr)
+ if s == 0: return None
+ else: return s
+
+ def set_srid(self, srid):
+ "Sets the SRID for the geometry."
+ geos_set_srid(self.ptr, srid)
+ srid = property(get_srid, set_srid)
+
+ #### Output Routines ####
+ @property
+ def ewkt(self):
+ "Returns the EWKT (WKT + SRID) of the Geometry."
+ if self.get_srid(): return 'SRID=%s;%s' % (self.srid, self.wkt)
+ else: return self.wkt
+
+ @property
+ def wkt(self):
+ "Returns the WKT (Well-Known Text) of the Geometry."
+ return to_wkt(self.ptr)
+
+ @property
+ def hex(self):
+ """
+ Returns the HEX of the Geometry -- please note that the SRID is not
+ included in this representation, because the GEOS C library uses
+ -1 by default, even if the SRID is set.
+ """
+ # A possible faster, all-python, implementation:
+ # str(self.wkb).encode('hex')
+ return to_hex(self.ptr, byref(c_size_t()))
+
+ @property
+ def json(self):
+ """
+ Returns GeoJSON representation of this Geometry if GDAL 1.5+
+ is installed.
+ """
+ if GEOJSON: return self.ogr.json
+ geojson = json
+
+ @property
+ def wkb(self):
+ "Returns the WKB of the Geometry as a buffer."
+ bin = to_wkb(self.ptr, byref(c_size_t()))
+ return buffer(bin)
+
+ @property
+ def kml(self):
+ "Returns the KML representation of this Geometry."
+ gtype = self.geom_type
+ return '<%s>%s</%s>' % (gtype, self.coord_seq.kml, gtype)
+
+ #### GDAL-specific output routines ####
+ @property
+ def ogr(self):
+ "Returns the OGR Geometry for this Geometry."
+ if HAS_GDAL:
+ if self.srid:
+ return OGRGeometry(self.wkb, self.srid)
+ else:
+ return OGRGeometry(self.wkb)
+ else:
+ return None
+
+ @property
+ def srs(self):
+ "Returns the OSR SpatialReference for SRID of this Geometry."
+ if HAS_GDAL and self.srid:
+ return SpatialReference(self.srid)
+ else:
+ return None
+
+ @property
+ def crs(self):
+ "Alias for `srs` property."
+ return self.srs
+
+ def transform(self, ct, clone=False):
+ """
+ Requires GDAL. Transforms the geometry according to the given
+ transformation object, which may be an integer SRID, and WKT or
+ PROJ.4 string. By default, the geometry is transformed in-place and
+ nothing is returned. However if the `clone` keyword is set, then this
+ geometry will not be modified and a transformed clone will be returned
+ instead.
+ """
+ srid = self.srid
+ if HAS_GDAL and srid:
+ g = OGRGeometry(self.wkb, srid)
+ g.transform(ct)
+ wkb = str(g.wkb)
+ ptr = from_wkb(wkb, len(wkb))
+ if clone:
+ # User wants a cloned transformed geometry returned.
+ return GEOSGeometry(ptr, srid=g.srid)
+ if ptr:
+ # Reassigning pointer, and performing post-initialization setup
+ # again due to the reassignment.
+ destroy_geom(self.ptr)
+ self._ptr = ptr
+ self._post_init(g.srid)
+ else:
+ raise GEOSException('Transformed WKB was invalid.')
+
+ #### Topology Routines ####
+ def _topology(self, gptr):
+ "Helper routine to return Geometry from the given pointer."
+ return GEOSGeometry(gptr, srid=self.srid)
+
+ @property
+ def boundary(self):
+ "Returns the boundary as a newly allocated Geometry object."
+ return self._topology(geos_boundary(self.ptr))
+
+ def buffer(self, width, quadsegs=8):
+ """
+ Returns a geometry that represents all points whose distance from this
+ Geometry is less than or equal to distance. Calculations are in the
+ Spatial Reference System of this Geometry. The optional third parameter sets
+ the number of segment used to approximate a quarter circle (defaults to 8).
+ (Text from PostGIS documentation at ch. 6.1.3)
+ """
+ return self._topology(geos_buffer(self.ptr, width, quadsegs))
+
+ @property
+ def centroid(self):
+ """
+ The centroid is equal to the centroid of the set of component Geometries
+ of highest dimension (since the lower-dimension geometries contribute zero
+ "weight" to the centroid).
+ """
+ return self._topology(geos_centroid(self.ptr))
+
+ @property
+ def convex_hull(self):
+ """
+ Returns the smallest convex Polygon that contains all the points
+ in the Geometry.
+ """
+ return self._topology(geos_convexhull(self.ptr))
+
+ def difference(self, other):
+ """
+ Returns a Geometry representing the points making up this Geometry
+ that do not make up other.
+ """
+ return self._topology(geos_difference(self.ptr, other.ptr))
+
+ @property
+ def envelope(self):
+ "Return the envelope for this geometry (a polygon)."
+ return self._topology(geos_envelope(self.ptr))
+
+ def intersection(self, other):
+ "Returns a Geometry representing the points shared by this Geometry and other."
+ return self._topology(geos_intersection(self.ptr, other.ptr))
+
+ @property
+ def point_on_surface(self):
+ "Computes an interior point of this Geometry."
+ return self._topology(geos_pointonsurface(self.ptr))
+
+ def relate(self, other):
+ "Returns the DE-9IM intersection matrix for this Geometry and the other."
+ return geos_relate(self.ptr, other.ptr)
+
+ def simplify(self, tolerance=0.0, preserve_topology=False):
+ """
+ Returns the Geometry, simplified using the Douglas-Peucker algorithm
+ to the specified tolerance (higher tolerance => less points). If no
+ tolerance provided, defaults to 0.
+
+ By default, this function does not preserve topology - e.g. polygons can
+ be split, collapse to lines or disappear holes can be created or
+ disappear, and lines can cross. By specifying preserve_topology=True,
+ the result will have the same dimension and number of components as the
+ input. This is significantly slower.
+ """
+ if preserve_topology:
+ return self._topology(geos_preservesimplify(self.ptr, tolerance))
+ else:
+ return self._topology(geos_simplify(self.ptr, tolerance))
+
+ def sym_difference(self, other):
+ """
+ Returns a set combining the points in this Geometry not in other,
+ and the points in other not in this Geometry.
+ """
+ return self._topology(geos_symdifference(self.ptr, other.ptr))
+
+ def union(self, other):
+ "Returns a Geometry representing all the points in this Geometry and other."
+ return self._topology(geos_union(self.ptr, other.ptr))
+
+ #### Other Routines ####
+ @property
+ def area(self):
+ "Returns the area of the Geometry."
+ return geos_area(self.ptr, byref(c_double()))
+
+ def distance(self, other):
+ """
+ Returns the distance between the closest points on this Geometry
+ and the other. Units will be in those of the coordinate system of
+ the Geometry.
+ """
+ if not isinstance(other, GEOSGeometry):
+ raise TypeError('distance() works only on other GEOS Geometries.')
+ return geos_distance(self.ptr, other.ptr, byref(c_double()))
+
+ @property
+ def extent(self):
+ """
+ Returns the extent of this geometry as a 4-tuple, consisting of
+ (xmin, ymin, xmax, ymax).
+ """
+ env = self.envelope
+ if isinstance(env, Point):
+ xmin, ymin = env.tuple
+ xmax, ymax = xmin, ymin
+ else:
+ xmin, ymin = env[0][0]
+ xmax, ymax = env[0][2]
+ return (xmin, ymin, xmax, ymax)
+
+ @property
+ def length(self):
+ """
+ Returns the length of this Geometry (e.g., 0 for point, or the
+ circumfrence of a Polygon).
+ """
+ return geos_length(self.ptr, byref(c_double()))
+
+ def clone(self):
+ "Clones this Geometry."
+ return GEOSGeometry(geom_clone(self.ptr), srid=self.srid)
+
+# Class mapping dictionary
+from django.contrib.gis.geos.geometries import Point, Polygon, LineString, LinearRing
+from django.contrib.gis.geos.collections import GeometryCollection, MultiPoint, MultiLineString, MultiPolygon
+GEOS_CLASSES = {0 : Point,
+ 1 : LineString,
+ 2 : LinearRing,
+ 3 : Polygon,
+ 4 : MultiPoint,
+ 5 : MultiLineString,
+ 6 : MultiPolygon,
+ 7 : GeometryCollection,
+ }