# Τεκμηρίωση του Django - 1.10.7

# Πηγαίος κώδικας για το django.contrib.gis.geos.geometry

    """
     This module contains the 'base' GEOSGeometry object -- all GEOS Geometries
     inherit from this object.
    """
    from __future__ import unicode_literals

    import json
    import warnings
    from ctypes import addressof, byref, c_double

    from django.contrib.gis import gdal
    from django.contrib.gis.geometry.regex import hex_regex, json_regex, wkt_regex
    from django.contrib.gis.geos import prototypes as capi
    from django.contrib.gis.geos.base import GEOSBase
    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
    from django.contrib.gis.geos.mutable_list import ListMixin
    from django.contrib.gis.geos.prepared import PreparedGeometry
    from django.contrib.gis.geos.prototypes.io import (
        ewkb_w, wkb_r, wkb_w, wkt_r, wkt_w,
    )
    from django.utils import six
    from django.utils.deconstruct import deconstructible
    from django.utils.deprecation import RemovedInDjango20Warning
    from django.utils.encoding import force_bytes, force_text

    @deconstructible
    class GEOSGeometry(GEOSBase, ListMixin):
        "A class that, generally, encapsulates a GEOS geometry."

        _GEOS_CLASSES = None

        ptr_type = GEOM_PTR
        has_cs = False  # Only Point, LineString, LinearRing have coordinate sequences

        def __init__(self, geo_input, srid=None):
            """
            The base constructor for GEOS geometry objects, and may take the
            following inputs:

             * strings:
                - WKT
                - HEXEWKB (a PostGIS-specific canonical form)
                - GeoJSON (requires GDAL)
             * 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, bytes):
                geo_input = force_text(geo_input)
            if isinstance(geo_input, six.string_types):
                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 = wkt_r().read(force_bytes(wkt_m.group('wkt')))
                elif hex_regex.match(geo_input):
                    # Handling HEXEWKB input.
                    g = wkb_r().read(force_bytes(geo_input))
                elif json_regex.match(geo_input):
                    # Handling GeoJSON input.
                    if not gdal.HAS_GDAL:
                        raise ValueError('Initializing geometry from JSON input requires GDAL.')
                    g = wkb_r().read(gdal.OGRGeometry(geo_input).wkb)
                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 geometry (GEOM_PTR).
                g = geo_input
            elif isinstance(geo_input, six.memoryview):
                # When the input is a buffer (WKB).
                g = wkb_r().read(geo_input)
            elif isinstance(geo_input, GEOSGeometry):
                g = capi.geom_clone(geo_input.ptr)
            else:
                # Invalid geometry type.
                raise TypeError('Improper geometry input type: %s' % str(type(geo_input)))

            if 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.)
            if GEOSGeometry._GEOS_CLASSES is None:
                # Lazy-loaded variable to avoid import conflicts with GEOSGeometry.
                from .linestring import LineString, LinearRing
                from .point import Point
                from .polygon import Polygon
                from .collections import (
                    GeometryCollection, MultiPoint, MultiLineString, MultiPolygon)
                GEOSGeometry._GEOS_CLASSES = {
                    0: Point,
                    1: LineString,
                    2: LinearRing,
                    3: Polygon,
                    4: MultiPoint,
                    5: MultiLineString,
                    6: MultiPolygon,
                    7: GeometryCollection,
                }
            self.__class__ = GEOSGeometry._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()

        def __del__(self):
            """
            Destroys this Geometry; in other words, frees the memory used by the
            GEOS C++ object.
            """
            try:
                capi.destroy_geom(self._ptr)
            except (AttributeError, TypeError):
                pass  # Some part might already have been garbage collected

        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):
            "EWKT is used for the string representation."
            return self.ewkt

        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 bytes(self.wkb), self.srid

        def __setstate__(self, state):
            # Instantiating from the tuple state that was pickled.
            wkb, srid = state
            ptr = wkb_r().read(six.memoryview(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, six.string_types):
                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 ####
        def _set_cs(self):
            "Sets the coordinate sequence for this Geometry."
            if self.has_cs:
                self._cs = GEOSCoordSeq(capi.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 capi.geos_type(self.ptr).decode()

        @property
        def geom_typeid(self):
            "Returns an integer representing the Geometry type."
            return capi.geos_typeid(self.ptr)

        @property
        def num_geom(self):
            "Returns the number of geometries in the Geometry."
            return capi.get_num_geoms(self.ptr)

        @property
        def num_coords(self):
            "Returns the number of coordinates in the Geometry."
            return capi.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 capi.get_dims(self.ptr)

        def normalize(self):
            "Converts this Geometry to normal form (or canonical form)."
            return capi.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 capi.geos_isempty(self.ptr)

        @property
        def hasz(self):
            "Returns whether the geometry has a 3D dimension."
            return capi.geos_hasz(self.ptr)

        @property
        def ring(self):
            "Returns whether or not the geometry is a ring."
            return capi.geos_isring(self.ptr)

        @property
        def simple(self):
            "Returns false if the Geometry not simple."
            return capi.geos_issimple(self.ptr)

        @property
        def valid(self):
            "This property tests the validity of this Geometry."
            return capi.geos_isvalid(self.ptr)

        @property
        def valid_reason(self):
            """
            Returns a string containing the reason for any invalidity.
            """
            return capi.geos_isvalidreason(self.ptr).decode()

        # #### Binary predicates. ####
        def contains(self, other):
            "Returns true if other.within(this) returns true."
            return capi.geos_contains(self.ptr, other.ptr)

        def covers(self, other):
            """
            Return True if the DE-9IM Intersection Matrix for the two geometries is
            T*****FF*, *T****FF*, ***T**FF*, or ****T*FF*. If either geometry is
            empty, return False.
            """
            return capi.geos_covers(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 capi.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 capi.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 capi.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 capi.geos_equalsexact(self.ptr, other.ptr, float(tolerance))

        def intersects(self, other):
            "Returns true if disjoint returns false."
            return capi.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 capi.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, six.string_types) or len(pattern) > 9:
                raise GEOSException('invalid intersection matrix pattern')
            return capi.geos_relatepattern(self.ptr, other.ptr, force_bytes(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 capi.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 capi.geos_within(self.ptr, other.ptr)

        # #### SRID Routines ####
        @property
        def srid(self):
            "Gets the SRID for the geometry, returns None if no SRID is set."
            s = capi.geos_get_srid(self.ptr)
            if s == 0:
                return None
            else:
                return s

        @srid.setter
        def srid(self, srid):
            "Sets the SRID for the geometry."
            capi.geos_set_srid(self.ptr, 0 if srid is None else srid)

        def get_srid(self):
            warnings.warn(
                "`get_srid()` is deprecated, use the `srid` property instead.",
                RemovedInDjango20Warning, 2
            )
            return self.srid

        def set_srid(self, srid):
            warnings.warn(
                "`set_srid()` is deprecated, use the `srid` property instead.",
                RemovedInDjango20Warning, 2
            )
            self.srid = srid

        # #### Output Routines ####
        @property
        def ewkt(self):
            """
            Returns the EWKT (SRID + WKT) of the Geometry.
            """
            srid = self.srid
            return 'SRID=%s;%s' % (srid, self.wkt) if srid else self.wkt

        @property
        def wkt(self):
            "Returns the WKT (Well-Known Text) representation of this Geometry."
            return wkt_w(dim=3 if self.hasz else 2, trim=True).write(self).decode()

        @property
        def hex(self):
            """
            Returns the WKB of this Geometry in hexadecimal form.  Please note
            that the SRID is not included in this representation because it is not
            a part of the OGC specification (use the `hexewkb` property instead).
            """
            # A possible faster, all-python, implementation:
            #  str(self.wkb).encode('hex')
            return wkb_w(dim=3 if self.hasz else 2).write_hex(self)

        @property
        def hexewkb(self):
            """
            Returns the EWKB of this Geometry in hexadecimal form.  This is an
            extension of the WKB specification that includes SRID value that are
            a part of this geometry.
            """
            return ewkb_w(dim=3 if self.hasz else 2).write_hex(self)

        @property
        def json(self):
            """
            Returns GeoJSON representation of this Geometry.
            """
            return json.dumps({'type': self.__class__.__name__, 'coordinates': self.coords})
        geojson = json

        @property
        def wkb(self):
            """
            Returns the WKB (Well-Known Binary) representation of this Geometry
            as a Python buffer.  SRID and Z values are not included, use the
            `ewkb` property instead.
            """
            return wkb_w(3 if self.hasz else 2).write(self)

        @property
        def ewkb(self):
            """
            Return the EWKB representation of this Geometry as a Python buffer.
            This is an extension of the WKB specification that includes any SRID
            value that are a part of this geometry.
            """
            return ewkb_w(3 if self.hasz else 2).write(self)

        @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)

        @property
        def prepared(self):
            """
            Returns a PreparedGeometry corresponding to this geometry -- it is
            optimized for the contains, intersects, and covers operations.
            """
            return PreparedGeometry(self)

        # #### GDAL-specific output routines ####
        @property
        def ogr(self):
            "Returns the OGR Geometry for this Geometry."
            if not gdal.HAS_GDAL:
                raise GEOSException('GDAL required to convert to an OGRGeometry.')
            if self.srid:
                try:
                    return gdal.OGRGeometry(self.wkb, self.srid)
                except gdal.SRSException:
                    pass
            return gdal.OGRGeometry(self.wkb)

        @property
        def srs(self):
            "Returns the OSR SpatialReference for SRID of this Geometry."
            if not gdal.HAS_GDAL:
                raise GEOSException('GDAL required to return a SpatialReference object.')
            if self.srid:
                try:
                    return gdal.SpatialReference(self.srid)
                except gdal.SRSException:
                    pass
            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 ct == srid:
                # short-circuit where source & dest SRIDs match
                if clone:
                    return self.clone()
                else:
                    return

            if not gdal.HAS_GDAL:
                raise GEOSException("GDAL library is not available to transform() geometry.")

            if isinstance(ct, gdal.CoordTransform):
                # We don't care about SRID because CoordTransform presupposes
                # source SRS.
                srid = None
            elif srid is None or srid < 0:
                raise GEOSException("Calling transform() with no SRID set is not supported")

            # Creating an OGR Geometry, which is then transformed.
            g = gdal.OGRGeometry(self.wkb, srid)
            g.transform(ct)
            # Getting a new GEOS pointer
            ptr = wkb_r().read(g.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.
                capi.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(capi.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(capi.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(capi.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(capi.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(capi.geos_difference(self.ptr, other.ptr))

        @property
        def envelope(self):
            "Return the envelope for this geometry (a polygon)."
            return self._topology(capi.geos_envelope(self.ptr))

        def intersection(self, other):
            "Returns a Geometry representing the points shared by this Geometry and other."
            return self._topology(capi.geos_intersection(self.ptr, other.ptr))

        @property
        def point_on_surface(self):
            "Computes an interior point of this Geometry."
            return self._topology(capi.geos_pointonsurface(self.ptr))

        def relate(self, other):
            "Returns the DE-9IM intersection matrix for this Geometry and the other."
            return capi.geos_relate(self.ptr, other.ptr).decode()

        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(capi.geos_preservesimplify(self.ptr, tolerance))
            else:
                return self._topology(capi.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(capi.geos_symdifference(self.ptr, other.ptr))

        @property
        def unary_union(self):
            "Return the union of all the elements of this geometry."
            return self._topology(capi.geos_unary_union(self.ptr))

        def union(self, other):
            "Returns a Geometry representing all the points in this Geometry and other."
            return self._topology(capi.geos_union(self.ptr, other.ptr))

        # #### Other Routines ####
        @property
        def area(self):
            "Returns the area of the Geometry."
            return capi.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 capi.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).
            """
            from .point import Point
            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
            circumference of a Polygon).
            """
            return capi.geos_length(self.ptr, byref(c_double()))

        def clone(self):
            "Clones this Geometry."
            return GEOSGeometry(capi.geom_clone(self.ptr), srid=self.srid)

    class LinearGeometryMixin(object):
        """
        Used for LineString and MultiLineString.
        """
        def interpolate(self, distance):
            return self._topology(capi.geos_interpolate(self.ptr, distance))

        def interpolate_normalized(self, distance):
            return self._topology(capi.geos_interpolate_normalized(self.ptr, distance))

        def project(self, point):
            from .point import Point
            if not isinstance(point, Point):
                raise TypeError('locate_point argument must be a Point')
            return capi.geos_project(self.ptr, point.ptr)

        def project_normalized(self, point):
            from .point import Point
            if not isinstance(point, Point):
                raise TypeError('locate_point argument must be a Point')
            return capi.geos_project_normalized(self.ptr, point.ptr)

        @property
        def merged(self):
            """
            Return the line merge of this Geometry.
            """
            return self._topology(capi.geos_linemerge(self.ptr))

        @property
        def closed(self):
            """
            Return whether or not this Geometry is closed.
            """
            return capi.geos_isclosed(self.ptr)