| """ |
| 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, |
| } |
