|
1 """ |
|
2 This module houses the GEOSCoordSeq object, which is used internally |
|
3 by GEOSGeometry to house the actual coordinates of the Point, |
|
4 LineString, and LinearRing geometries. |
|
5 """ |
|
6 from ctypes import c_double, c_uint, byref |
|
7 from types import ListType, TupleType |
|
8 from django.contrib.gis.geos.error import GEOSException, GEOSIndexError |
|
9 from django.contrib.gis.geos.libgeos import CS_PTR, HAS_NUMPY |
|
10 from django.contrib.gis.geos.prototypes import cs_clone, cs_getdims, cs_getordinate, cs_getsize, cs_setordinate |
|
11 if HAS_NUMPY: from numpy import ndarray |
|
12 |
|
13 class GEOSCoordSeq(object): |
|
14 "The internal representation of a list of coordinates inside a Geometry." |
|
15 |
|
16 #### Python 'magic' routines #### |
|
17 def __init__(self, ptr, z=False): |
|
18 "Initializes from a GEOS pointer." |
|
19 if not isinstance(ptr, CS_PTR): |
|
20 raise TypeError('Coordinate sequence should initialize with a CS_PTR.') |
|
21 self._ptr = ptr |
|
22 self._z = z |
|
23 |
|
24 def __iter__(self): |
|
25 "Iterates over each point in the coordinate sequence." |
|
26 for i in xrange(self.size): |
|
27 yield self[i] |
|
28 |
|
29 def __len__(self): |
|
30 "Returns the number of points in the coordinate sequence." |
|
31 return int(self.size) |
|
32 |
|
33 def __str__(self): |
|
34 "Returns the string representation of the coordinate sequence." |
|
35 return str(self.tuple) |
|
36 |
|
37 def __getitem__(self, index): |
|
38 "Returns the coordinate sequence value at the given index." |
|
39 coords = [self.getX(index), self.getY(index)] |
|
40 if self.dims == 3 and self._z: |
|
41 coords.append(self.getZ(index)) |
|
42 return tuple(coords) |
|
43 |
|
44 def __setitem__(self, index, value): |
|
45 "Sets the coordinate sequence value at the given index." |
|
46 # Checking the input value |
|
47 if isinstance(value, (ListType, TupleType)): |
|
48 pass |
|
49 elif HAS_NUMPY and isinstance(value, ndarray): |
|
50 pass |
|
51 else: |
|
52 raise TypeError('Must set coordinate with a sequence (list, tuple, or numpy array).') |
|
53 # Checking the dims of the input |
|
54 if self.dims == 3 and self._z: |
|
55 n_args = 3 |
|
56 set_3d = True |
|
57 else: |
|
58 n_args = 2 |
|
59 set_3d = False |
|
60 if len(value) != n_args: |
|
61 raise TypeError('Dimension of value does not match.') |
|
62 # Setting the X, Y, Z |
|
63 self.setX(index, value[0]) |
|
64 self.setY(index, value[1]) |
|
65 if set_3d: self.setZ(index, value[2]) |
|
66 |
|
67 #### Internal Routines #### |
|
68 def _checkindex(self, index): |
|
69 "Checks the given index." |
|
70 sz = self.size |
|
71 if (sz < 1) or (index < 0) or (index >= sz): |
|
72 raise GEOSIndexError('invalid GEOS Geometry index: %s' % str(index)) |
|
73 |
|
74 def _checkdim(self, dim): |
|
75 "Checks the given dimension." |
|
76 if dim < 0 or dim > 2: |
|
77 raise GEOSException('invalid ordinate dimension "%d"' % dim) |
|
78 |
|
79 @property |
|
80 def ptr(self): |
|
81 """ |
|
82 Property for controlling access to coordinate sequence pointer, |
|
83 preventing attempted access to a NULL memory location. |
|
84 """ |
|
85 if self._ptr: return self._ptr |
|
86 else: raise GEOSException('NULL coordinate sequence pointer encountered.') |
|
87 |
|
88 #### Ordinate getting and setting routines #### |
|
89 def getOrdinate(self, dimension, index): |
|
90 "Returns the value for the given dimension and index." |
|
91 self._checkindex(index) |
|
92 self._checkdim(dimension) |
|
93 return cs_getordinate(self.ptr, index, dimension, byref(c_double())) |
|
94 |
|
95 def setOrdinate(self, dimension, index, value): |
|
96 "Sets the value for the given dimension and index." |
|
97 self._checkindex(index) |
|
98 self._checkdim(dimension) |
|
99 cs_setordinate(self.ptr, index, dimension, value) |
|
100 |
|
101 def getX(self, index): |
|
102 "Get the X value at the index." |
|
103 return self.getOrdinate(0, index) |
|
104 |
|
105 def setX(self, index, value): |
|
106 "Set X with the value at the given index." |
|
107 self.setOrdinate(0, index, value) |
|
108 |
|
109 def getY(self, index): |
|
110 "Get the Y value at the given index." |
|
111 return self.getOrdinate(1, index) |
|
112 |
|
113 def setY(self, index, value): |
|
114 "Set Y with the value at the given index." |
|
115 self.setOrdinate(1, index, value) |
|
116 |
|
117 def getZ(self, index): |
|
118 "Get Z with the value at the given index." |
|
119 return self.getOrdinate(2, index) |
|
120 |
|
121 def setZ(self, index, value): |
|
122 "Set Z with the value at the given index." |
|
123 self.setOrdinate(2, index, value) |
|
124 |
|
125 ### Dimensions ### |
|
126 @property |
|
127 def size(self): |
|
128 "Returns the size of this coordinate sequence." |
|
129 return cs_getsize(self.ptr, byref(c_uint())) |
|
130 |
|
131 @property |
|
132 def dims(self): |
|
133 "Returns the dimensions of this coordinate sequence." |
|
134 return cs_getdims(self.ptr, byref(c_uint())) |
|
135 |
|
136 @property |
|
137 def hasz(self): |
|
138 """ |
|
139 Returns whether this coordinate sequence is 3D. This property value is |
|
140 inherited from the parent Geometry. |
|
141 """ |
|
142 return self._z |
|
143 |
|
144 ### Other Methods ### |
|
145 def clone(self): |
|
146 "Clones this coordinate sequence." |
|
147 return GEOSCoordSeq(cs_clone(self.ptr), self.hasz) |
|
148 |
|
149 @property |
|
150 def kml(self): |
|
151 "Returns the KML representation for the coordinates." |
|
152 # Getting the substitution string depending on whether the coordinates have |
|
153 # a Z dimension. |
|
154 if self.hasz: substr = '%s,%s,%s ' |
|
155 else: substr = '%s,%s,0 ' |
|
156 return '<coordinates>%s</coordinates>' % \ |
|
157 ''.join([substr % self[i] for i in xrange(len(self))]).strip() |
|
158 |
|
159 @property |
|
160 def tuple(self): |
|
161 "Returns a tuple version of this coordinate sequence." |
|
162 n = self.size |
|
163 if n == 1: return self[0] |
|
164 else: return tuple([self[i] for i in xrange(n)]) |