221 lines
7.1 KiB
Python
221 lines
7.1 KiB
Python
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"""
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This module houses the GEOSCoordSeq object, which is used internally
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by GEOSGeometry to house the actual coordinates of the Point,
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LineString, and LinearRing geometries.
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"""
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from ctypes import byref, c_byte, c_double, c_uint
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from django.contrib.gis.geos import prototypes as capi
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from django.contrib.gis.geos.base import GEOSBase
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from django.contrib.gis.geos.error import GEOSException
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from django.contrib.gis.geos.libgeos import CS_PTR, geos_version_tuple
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from django.contrib.gis.shortcuts import numpy
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class GEOSCoordSeq(GEOSBase):
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"The internal representation of a list of coordinates inside a Geometry."
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ptr_type = CS_PTR
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def __init__(self, ptr, z=False):
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"Initialize from a GEOS pointer."
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if not isinstance(ptr, CS_PTR):
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raise TypeError("Coordinate sequence should initialize with a CS_PTR.")
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self._ptr = ptr
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self._z = z
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def __iter__(self):
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"Iterate over each point in the coordinate sequence."
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for i in range(self.size):
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yield self[i]
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def __len__(self):
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"Return the number of points in the coordinate sequence."
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return self.size
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def __str__(self):
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"Return the string representation of the coordinate sequence."
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return str(self.tuple)
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def __getitem__(self, index):
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"Return the coordinate sequence value at the given index."
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self._checkindex(index)
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return self._point_getter(index)
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def __setitem__(self, index, value):
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"Set the coordinate sequence value at the given index."
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# Checking the input value
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if isinstance(value, (list, tuple)):
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pass
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elif numpy and isinstance(value, numpy.ndarray):
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pass
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else:
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raise TypeError(
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"Must set coordinate with a sequence (list, tuple, or numpy array)."
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)
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# Checking the dims of the input
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if self.dims == 3 and self._z:
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n_args = 3
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point_setter = self._set_point_3d
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else:
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n_args = 2
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point_setter = self._set_point_2d
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if len(value) != n_args:
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raise TypeError("Dimension of value does not match.")
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self._checkindex(index)
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point_setter(index, value)
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# #### Internal Routines ####
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def _checkindex(self, index):
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"Check the given index."
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if not (0 <= index < self.size):
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raise IndexError("invalid GEOS Geometry index: %s" % index)
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def _checkdim(self, dim):
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"Check the given dimension."
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if dim < 0 or dim > 2:
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raise GEOSException('invalid ordinate dimension "%d"' % dim)
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def _get_x(self, index):
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return capi.cs_getx(self.ptr, index, byref(c_double()))
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def _get_y(self, index):
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return capi.cs_gety(self.ptr, index, byref(c_double()))
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def _get_z(self, index):
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return capi.cs_getz(self.ptr, index, byref(c_double()))
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def _set_x(self, index, value):
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capi.cs_setx(self.ptr, index, value)
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def _set_y(self, index, value):
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capi.cs_sety(self.ptr, index, value)
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def _set_z(self, index, value):
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capi.cs_setz(self.ptr, index, value)
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@property
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def _point_getter(self):
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return self._get_point_3d if self.dims == 3 and self._z else self._get_point_2d
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def _get_point_2d(self, index):
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return (self._get_x(index), self._get_y(index))
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def _get_point_3d(self, index):
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return (self._get_x(index), self._get_y(index), self._get_z(index))
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def _set_point_2d(self, index, value):
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x, y = value
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self._set_x(index, x)
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self._set_y(index, y)
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def _set_point_3d(self, index, value):
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x, y, z = value
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self._set_x(index, x)
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self._set_y(index, y)
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self._set_z(index, z)
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# #### Ordinate getting and setting routines ####
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def getOrdinate(self, dimension, index):
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"Return the value for the given dimension and index."
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self._checkindex(index)
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self._checkdim(dimension)
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return capi.cs_getordinate(self.ptr, index, dimension, byref(c_double()))
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def setOrdinate(self, dimension, index, value):
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"Set the value for the given dimension and index."
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self._checkindex(index)
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self._checkdim(dimension)
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capi.cs_setordinate(self.ptr, index, dimension, value)
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def getX(self, index):
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"Get the X value at the index."
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return self.getOrdinate(0, index)
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def setX(self, index, value):
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"Set X with the value at the given index."
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self.setOrdinate(0, index, value)
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def getY(self, index):
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"Get the Y value at the given index."
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return self.getOrdinate(1, index)
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def setY(self, index, value):
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"Set Y with the value at the given index."
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self.setOrdinate(1, index, value)
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def getZ(self, index):
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"Get Z with the value at the given index."
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return self.getOrdinate(2, index)
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def setZ(self, index, value):
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"Set Z with the value at the given index."
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self.setOrdinate(2, index, value)
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# ### Dimensions ###
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@property
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def size(self):
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"Return the size of this coordinate sequence."
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return capi.cs_getsize(self.ptr, byref(c_uint()))
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@property
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def dims(self):
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"Return the dimensions of this coordinate sequence."
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return capi.cs_getdims(self.ptr, byref(c_uint()))
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@property
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def hasz(self):
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"""
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Return whether this coordinate sequence is 3D. This property value is
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inherited from the parent Geometry.
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"""
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return self._z
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# ### Other Methods ###
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def clone(self):
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"Clone this coordinate sequence."
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return GEOSCoordSeq(capi.cs_clone(self.ptr), self.hasz)
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@property
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def kml(self):
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"Return the KML representation for the coordinates."
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# Getting the substitution string depending on whether the coordinates have
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# a Z dimension.
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if self.hasz:
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substr = "%s,%s,%s "
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else:
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substr = "%s,%s,0 "
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return (
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"<coordinates>%s</coordinates>"
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% "".join(substr % self[i] for i in range(len(self))).strip()
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)
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@property
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def tuple(self):
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"Return a tuple version of this coordinate sequence."
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n = self.size
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get_point = self._point_getter
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if n == 1:
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return get_point(0)
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return tuple(get_point(i) for i in range(n))
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@property
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def is_counterclockwise(self):
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"""Return whether this coordinate sequence is counterclockwise."""
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if geos_version_tuple() < (3, 7):
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# A modified shoelace algorithm to determine polygon orientation.
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# See https://en.wikipedia.org/wiki/Shoelace_formula.
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area = 0.0
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n = len(self)
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for i in range(n):
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j = (i + 1) % n
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area += self[i][0] * self[j][1]
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area -= self[j][0] * self[i][1]
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return area > 0.0
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ret = c_byte()
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if not capi.cs_is_ccw(self.ptr, byref(ret)):
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raise GEOSException(
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'Error encountered in GEOS C function "%s".' % capi.cs_is_ccw.func_name
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)
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return ret.value == 1
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