# -*- coding: utf-8 -*-
'''
feedgen.ext.geo_entry
~~~~~~~~~~~~~~~~~~~
Extends the FeedGenerator to produce Simple GeoRSS feeds.
:copyright: 2017, Bob Breznak <bob.breznak@gmail.com>
:license: FreeBSD and LGPL, see license.* for more details.
'''
import numbers
import warnings
from lxml import etree
from feedgen.ext.base import BaseEntryExtension
class GeoRSSPolygonInteriorWarning(Warning):
"""
Simple placeholder for warning about ignored polygon interiors.
Stores the original geom on a ``geom`` attribute (if required warnings are
raised as errors).
"""
def __init__(self, geom, *args, **kwargs):
self.geom = geom
super(GeoRSSPolygonInteriorWarning, self).__init__(*args, **kwargs)
def __str__(self):
return '{:d} interiors of polygon ignored'.format(
len(self.geom.__geo_interface__['coordinates']) - 1
) # ignore exterior in count
class GeoRSSGeometryError(ValueError):
"""
Subclass of ValueError for a GeoRSS geometry error
Only some geometries are supported in Simple GeoRSS, so if not raise an
error. Offending geometry is stored on the ``geom`` attribute.
"""
def __init__(self, geom, *args, **kwargs):
self.geom = geom
super(GeoRSSGeometryError, self).__init__(*args, **kwargs)
def __str__(self):
msg = "Geometry of type '{}' not in Point, Linestring or Polygon"
return msg.format(
self.geom.__geo_interface__['type']
)
class GeoEntryExtension(BaseEntryExtension):
'''FeedEntry extension for Simple GeoRSS.
'''
def __init__(self):
'''Simple GeoRSS tag'''
# geometries
self.__point = None
self.__line = None
self.__polygon = None
self.__box = None
# additional properties
self.__featuretypetag = None
self.__relationshiptag = None
self.__featurename = None
# elevation
self.__elev = None
self.__floor = None
# radius
self.__radius = None
def extend_file(self, entry):
'''Add additional fields to an RSS item.
:param feed: The RSS item XML element to use.
'''
GEO_NS = 'http://www.georss.org/georss'
if self.__point:
point = etree.SubElement(entry, '{%s}point' % GEO_NS)
point.text = self.__point
if self.__line:
line = etree.SubElement(entry, '{%s}line' % GEO_NS)
line.text = self.__line
if self.__polygon:
polygon = etree.SubElement(entry, '{%s}polygon' % GEO_NS)
polygon.text = self.__polygon
if self.__box:
box = etree.SubElement(entry, '{%s}box' % GEO_NS)
box.text = self.__box
if self.__featuretypetag:
featuretypetag = etree.SubElement(
entry,
'{%s}featuretypetag' % GEO_NS
)
featuretypetag.text = self.__featuretypetag
if self.__relationshiptag:
relationshiptag = etree.SubElement(
entry,
'{%s}relationshiptag' % GEO_NS
)
relationshiptag.text = self.__relationshiptag
if self.__featurename:
featurename = etree.SubElement(entry, '{%s}featurename' % GEO_NS)
featurename.text = self.__featurename
if self.__elev:
elevation = etree.SubElement(entry, '{%s}elev' % GEO_NS)
elevation.text = str(self.__elev)
if self.__floor:
floor = etree.SubElement(entry, '{%s}floor' % GEO_NS)
floor.text = str(self.__floor)
if self.__radius:
radius = etree.SubElement(entry, '{%s}radius' % GEO_NS)
radius.text = str(self.__radius)
return entry
def extend_rss(self, entry):
return self.extend_file(entry)
def extend_atom(self, entry):
return self.extend_file(entry)
def point(self, point=None):
'''Get or set the georss:point of the entry.
:param point: The GeoRSS formatted point (i.e. "42.36 -71.05")
:returns: The current georss:point of the entry.
'''
if point is not None:
self.__point = point
return self.__point
def line(self, line=None):
'''Get or set the georss:line of the entry
:param point: The GeoRSS formatted line (i.e. "45.256 -110.45 46.46
-109.48 43.84 -109.86")
:return: The current georss:line of the entry
'''
if line is not None:
self.__line = line
return self.__line
def polygon(self, polygon=None):
'''Get or set the georss:polygon of the entry
:param polygon: The GeoRSS formatted polygon (i.e. "45.256 -110.45
46.46 -109.48 43.84 -109.86 45.256 -110.45")
:return: The current georss:polygon of the entry
'''
if polygon is not None:
self.__polygon = polygon
return self.__polygon
def box(self, box=None):
'''
Get or set the georss:box of the entry
:param box: The GeoRSS formatted box (i.e. "42.943 -71.032 43.039
-69.856")
:return: The current georss:box of the entry
'''
if box is not None:
self.__box = box
return self.__box
def featuretypetag(self, featuretypetag=None):
'''
Get or set the georss:featuretypetag of the entry
:param featuretypetag: The GeoRSS feaaturertyptag (e.g. "city")
:return: The current georss:featurertypetag
'''
if featuretypetag is not None:
self.__featuretypetag = featuretypetag
return self.__featuretypetag
def relationshiptag(self, relationshiptag=None):
'''
Get or set the georss:relationshiptag of the entry
:param relationshiptag: The GeoRSS relationshiptag (e.g.
"is-centred-at")
:return: the current georss:relationshiptag
'''
if relationshiptag is not None:
self.__relationshiptag = relationshiptag
return self.__relationshiptag
def featurename(self, featurename=None):
'''
Get or set the georss:featurename of the entry
:param featuretypetag: The GeoRSS featurename (e.g. "Footscray")
:return: the current georss:featurename
'''
if featurename is not None:
self.__featurename = featurename
return self.__featurename
def elev(self, elev=None):
'''
Get or set the georss:elev of the entry
:param elev: The GeoRSS elevation (e.g. 100.3)
:type elev: numbers.Number
:return: the current georss:elev
'''
if elev is not None:
if not isinstance(elev, numbers.Number):
raise ValueError("elev tag must be numeric: {}".format(elev))
self.__elev = elev
return self.__elev
def floor(self, floor=None):
'''
Get or set the georss:floor of the entry
:param floor: The GeoRSS floor (e.g. 4)
:type floor: int
:return: the current georss:floor
'''
if floor is not None:
if not isinstance(floor, int):
raise ValueError("floor tag must be int: {}".format(floor))
self.__floor = floor
return self.__floor
def radius(self, radius=None):
'''
Get or set the georss:radius of the entry
:param radius: The GeoRSS radius (e.g. 100.3)
:type radius: numbers.Number
:return: the current georss:radius
'''
if radius is not None:
if not isinstance(radius, numbers.Number):
raise ValueError(
"radius tag must be numeric: {}".format(radius)
)
self.__radius = radius
return self.__radius
def geom_from_geo_interface(self, geom):
'''
Generate a georss geometry from some Python object with a
``__geo_interface__`` property (see the `geo_interface specification by
Sean Gillies`_geointerface )
Note only a subset of GeoJSON (see `geojson.org`_geojson ) can be
easily converted to GeoRSS:
- Point
- LineString
- Polygon (if there are holes / donuts in the polygons a warning will
be generaated
Other GeoJson types will raise a ``ValueError``.
.. note:: The geometry is assumed to be x, y as longitude, latitude in
the WGS84 projection.
.. _geointerface: https://gist.github.com/sgillies/2217756
.. _geojson: https://geojson.org/
:param geom: Geometry object with a __geo_interface__ property
:return: the formatted GeoRSS geometry
'''
geojson = geom.__geo_interface__
if geojson['type'] not in ('Point', 'LineString', 'Polygon'):
raise GeoRSSGeometryError(geom)
if geojson['type'] == 'Point':
coords = '{:f} {:f}'.format(
geojson['coordinates'][1], # latitude is y
geojson['coordinates'][0]
)
return self.point(coords)
elif geojson['type'] == 'LineString':
coords = ' '.join(
'{:f} {:f}'.format(vertex[1], vertex[0])
for vertex in
geojson['coordinates']
)
return self.line(coords)
elif geojson['type'] == 'Polygon':
if len(geojson['coordinates']) > 1:
warnings.warn(GeoRSSPolygonInteriorWarning(geom))
coords = ' '.join(
'{:f} {:f}'.format(vertex[1], vertex[0])
for vertex in
geojson['coordinates'][0]
)
return self.polygon(coords)