python-mapnik 1:0.0~20151125-92e79d2-1build1 / usr / lib / python2.7 / dist-packages / mapnik / __init__.py

#
# This file is part of Mapnik (C++/Python mapping toolkit)
# Copyright (C) 2014 Artem Pavlenko
#
# Mapnik is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#

"""Mapnik Python module.

Boost Python bindings to the Mapnik C++ shared library.

Several things happen when you do:

    >>> import mapnik

 1) Mapnik C++ objects are imported via the '__init__.py' from the '_mapnik.so' shared object
    (_mapnik.pyd on win) which references libmapnik.so (linux), libmapnik.dylib (mac), or
    mapnik.dll (win32).

 2) The paths to the input plugins and font directories are imported from the 'paths.py'
    file which was constructed and installed during SCons installation.

 3) All available input plugins and TrueType fonts are automatically registered.

 4) Boost Python metaclass injectors are used in the '__init__.py' to extend several
    objects adding extra convenience when accessed via Python.

"""

import itertools
import os
import warnings
try:
    import json
except ImportError:
    import simplejson as json


def bootstrap_env():
    """
    If an optional settings file exists, inherit its
    environment settings before loading the mapnik library.

    This feature is intended for customized packages of mapnik.

    The settings file should be a python file with an 'env' variable
    that declares a dictionary of key:value pairs to push into the
    global process environment, if not already set, like:

        env = {'ICU_DATA':'/usr/local/share/icu/'}
    """
    if os.path.exists(os.path.join(
            os.path.dirname(__file__), 'mapnik_settings.py')):
        from .mapnik_settings import env
        process_keys = os.environ.keys()
        for key, value in env.items():
            if key not in process_keys:
                os.environ[key] = value

bootstrap_env()

from ._mapnik import *

from . import printing
printing.renderer = render

# The base Boost.Python class
BoostPythonMetaclass = Coord.__class__


class _MapnikMetaclass(BoostPythonMetaclass):

    def __init__(self, name, bases, dict):
        for b in bases:
            if type(b) not in (self, type):
                for k, v in list(dict.items()):
                    if hasattr(b, k):
                        setattr(b, '_c_' + k, getattr(b, k))
                    setattr(b, k, v)
        return type.__init__(self, name, bases, dict)

# metaclass injector compatible with both python 2 and 3
# http://mikewatkins.ca/2008/11/29/python-2-and-3-metaclasses/
_injector = _MapnikMetaclass('_injector', (object, ), {})


def Filter(*args, **kwargs):
    warnings.warn("'Filter' is deprecated and will be removed in Mapnik 3.x, use 'Expression' instead",
                  DeprecationWarning, 2)
    return Expression(*args, **kwargs)


class Envelope(Box2d):

    def __init__(self, *args, **kwargs):
        warnings.warn("'Envelope' is deprecated and will be removed in Mapnik 3.x, use 'Box2d' instead",
                      DeprecationWarning, 2)
        Box2d.__init__(self, *args, **kwargs)


class Coord(Coord, _injector):
    """
    Represents a point with two coordinates (either lon/lat or x/y).

    Following operators are defined for Coord:

    Addition and subtraction of Coord objects:

    >>> Coord(10, 10) + Coord(20, 20)
    Coord(30.0, 30.0)
    >>> Coord(10, 10) - Coord(20, 20)
    Coord(-10.0, -10.0)

    Addition, subtraction, multiplication and division between
    a Coord and a float:

    >>> Coord(10, 10) + 1
    Coord(11.0, 11.0)
    >>> Coord(10, 10) - 1
    Coord(-9.0, -9.0)
    >>> Coord(10, 10) * 2
    Coord(20.0, 20.0)
    >>> Coord(10, 10) / 2
    Coord(5.0, 5.0)

    Equality of coords (as pairwise equality of components):
    >>> Coord(10, 10) is Coord(10, 10)
    False
    >>> Coord(10, 10) == Coord(10, 10)
    True
    """

    def __repr__(self):
        return 'Coord(%s,%s)' % (self.x, self.y)

    def forward(self, projection):
        """
        Projects the point from the geographic coordinate
        space  into the cartesian space. The x component is
        considered to be longitude, the y component the
        latitude.

        Returns the easting (x) and northing (y) as a
        coordinate pair.

        Example: Project the geographic coordinates of the
                 city center of Stuttgart into the local
                 map projection (GK Zone 3/DHDN, EPSG 31467)
        >>> p = Projection('+init=epsg:31467')
        >>> Coord(9.1, 48.7).forward(p)
        Coord(3507360.12813,5395719.2749)
        """
        return forward_(self, projection)

    def inverse(self, projection):
        """
        Projects the point from the cartesian space
        into the geographic space. The x component is
        considered to be the easting, the y component
        to be the northing.

        Returns the longitude (x) and latitude (y) as a
        coordinate pair.

        Example: Project the cartesian coordinates of the
                 city center of Stuttgart in the local
                 map projection (GK Zone 3/DHDN, EPSG 31467)
                 into geographic coordinates:
        >>> p = Projection('+init=epsg:31467')
        >>> Coord(3507360.12813,5395719.2749).inverse(p)
        Coord(9.1, 48.7)
        """
        return inverse_(self, projection)


class Box2d(Box2d, _injector):
    """
    Represents a spatial envelope (i.e. bounding box).


    Following operators are defined for Box2d:

    Addition:
    e1 + e2 is equivalent to e1.expand_to_include(e2) but yields
    a new envelope instead of modifying e1

    Subtraction:
    Currently e1 - e2 returns e1.

    Multiplication and division with floats:
    Multiplication and division change the width and height of the envelope
    by the given factor without modifying its center..

    That is, e1 * x is equivalent to:
           e1.width(x * e1.width())
           e1.height(x * e1.height()),
    except that a new envelope is created instead of modifying e1.

    e1 / x is equivalent to e1 * (1.0/x).

    Equality: two envelopes are equal if their corner points are equal.
    """

    def __repr__(self):
        return 'Box2d(%s,%s,%s,%s)' % \
            (self.minx, self.miny, self.maxx, self.maxy)

    def forward(self, projection):
        """
        Projects the envelope from the geographic space
        into the cartesian space by projecting its corner
        points.

        See also:
           Coord.forward(self, projection)
        """
        return forward_(self, projection)

    def inverse(self, projection):
        """
        Projects the envelope from the cartesian space
        into the geographic space by projecting its corner
        points.

        See also:
          Coord.inverse(self, projection).
        """
        return inverse_(self, projection)


class Projection(Projection, _injector):

    def __repr__(self):
        return "Projection('%s')" % self.params()

    def forward(self, obj):
        """
        Projects the given object (Box2d or Coord)
        from the geographic space into the cartesian space.

        See also:
          Box2d.forward(self, projection),
          Coord.forward(self, projection).
        """
        return forward_(obj, self)

    def inverse(self, obj):
        """
        Projects the given object (Box2d or Coord)
        from the cartesian space into the geographic space.

        See also:
          Box2d.inverse(self, projection),
          Coord.inverse(self, projection).
        """
        return inverse_(obj, self)


class Feature(Feature, _injector):
    __geo_interface__ = property(lambda self: json.loads(self.to_geojson()))


class Geometry(Geometry, _injector):
    __geo_interface__ = property(lambda self: json.loads(self.to_geojson()))


class Datasource(Datasource, _injector):

    def all_features(self, fields=None, variables={}):
        query = Query(self.envelope())
        query.set_variables(variables)
        attributes = fields or self.fields()
        for fld in attributes:
            query.add_property_name(fld)
        return self.features(query).features

    def featureset(self, fields=None, variables={}):
        query = Query(self.envelope())
        query.set_variables(variables)
        attributes = fields or self.fields()
        for fld in attributes:
            query.add_property_name(fld)
        return self.features(query)


class Color(Color, _injector):

    def __repr__(self):
        return "Color(R=%d,G=%d,B=%d,A=%d)" % (self.r, self.g, self.b, self.a)


class _SymbolizerBase(SymbolizerBase, _injector):
    # back compatibility

    @property
    def filename(self):
        return self['file']

    @filename.setter
    def filename(self, val):
        self['file'] = val


def _add_symbol_method_to_symbolizers(vars=globals()):

    def symbol_for_subcls(self):
        return self

    def symbol_for_cls(self):
        return getattr(self, self.type())()

    for name, obj in vars.items():
        if name.endswith('Symbolizer') and not name.startswith('_'):
            if name == 'Symbolizer':
                symbol = symbol_for_cls
            else:
                symbol = symbol_for_subcls
            type('dummy', (obj, _injector), {'symbol': symbol})
_add_symbol_method_to_symbolizers()


def Datasource(**keywords):
    """Wrapper around CreateDatasource.

    Create a Mapnik Datasource using a dictionary of parameters.

    Keywords must include:

      type='plugin_name' # e.g. type='gdal'

    See the convenience factory methods of each input plugin for
    details on additional required keyword arguments.

    """

    return CreateDatasource(keywords)

# convenience factory methods


def Shapefile(**keywords):
    """Create a Shapefile Datasource.

    Required keyword arguments:
      file -- path to shapefile without extension

    Optional keyword arguments:
      base -- path prefix (default None)
      encoding -- file encoding (default 'utf-8')

    >>> from mapnik import Shapefile, Layer
    >>> shp = Shapefile(base='/home/mapnik/data',file='world_borders')
    >>> lyr = Layer('Shapefile Layer')
    >>> lyr.datasource = shp

    """
    keywords['type'] = 'shape'
    return CreateDatasource(keywords)


def CSV(**keywords):
    """Create a CSV Datasource.

    Required keyword arguments:
      file -- path to csv

    Optional keyword arguments:
      inline -- inline CSV string (if provided 'file' argument will be ignored and non-needed)
      base -- path prefix (default None)
      encoding -- file encoding (default 'utf-8')
      row_limit -- integer limit of rows to return (default: 0)
      strict -- throw an error if an invalid row is encountered
      escape -- The escape character to use for parsing data
      quote -- The quote character to use for parsing data
      separator -- The separator character to use for parsing data
      headers -- A comma separated list of header names that can be set to add headers to data that lacks them
      filesize_max -- The maximum filesize in MB that will be accepted

    >>> from mapnik import CSV
    >>> csv = CSV(file='test.csv')

    >>> from mapnik import CSV
    >>> csv = CSV(inline='''wkt,Name\n"POINT (120.15 48.47)","Winthrop, WA"''')

    For more information see https://github.com/mapnik/mapnik/wiki/CSV-Plugin

    """
    keywords['type'] = 'csv'
    return CreateDatasource(keywords)


def GeoJSON(**keywords):
    """Create a GeoJSON Datasource.

    Required keyword arguments:
      file -- path to json

    Optional keyword arguments:
      encoding -- file encoding (default 'utf-8')
      base -- path prefix (default None)

    >>> from mapnik import GeoJSON
    >>> geojson = GeoJSON(file='test.json')

    """
    keywords['type'] = 'geojson'
    return CreateDatasource(keywords)


def PostGIS(**keywords):
    """Create a PostGIS Datasource.

    Required keyword arguments:
      dbname -- database name to connect to
      table -- table name or subselect query

      *Note: if using subselects for the 'table' value consider also
       passing the 'geometry_field' and 'srid' and 'extent_from_subquery'
       options and/or specifying the 'geometry_table' option.

    Optional db connection keyword arguments:
      user -- database user to connect as (default: see postgres docs)
      password -- password for database user (default: see postgres docs)
      host -- postgres hostname (default: see postgres docs)
      port -- postgres port (default: see postgres docs)
      initial_size -- integer size of connection pool (default: 1)
      max_size -- integer max of connection pool (default: 10)
      persist_connection -- keep connection open (default: True)

    Optional table-level keyword arguments:
      extent -- manually specified data extent (comma delimited string, default: None)
      estimate_extent -- boolean, direct PostGIS to use the faster, less accurate `estimate_extent` over `extent` (default: False)
      extent_from_subquery -- boolean, direct Mapnik to query Postgis for the extent of the raw 'table' value (default: uses 'geometry_table')
      geometry_table -- specify geometry table to use to look up metadata (default: automatically parsed from 'table' value)
      geometry_field -- specify geometry field to use (default: first entry in geometry_columns)
      srid -- specify srid to use (default: auto-detected from geometry_field)
      row_limit -- integer limit of rows to return (default: 0)
      cursor_size -- integer size of binary cursor to use (default: 0, no binary cursor is used)

    >>> from mapnik import PostGIS, Layer
    >>> params = dict(dbname=env['MAPNIK_NAME'],table='osm',user='postgres',password='gis')
    >>> params['estimate_extent'] = False
    >>> params['extent'] = '-20037508,-19929239,20037508,19929239'
    >>> postgis = PostGIS(**params)
    >>> lyr = Layer('PostGIS Layer')
    >>> lyr.datasource = postgis

    """
    keywords['type'] = 'postgis'
    return CreateDatasource(keywords)


def PgRaster(**keywords):
    """Create a PgRaster Datasource.

    Required keyword arguments:
      dbname -- database name to connect to
      table -- table name or subselect query

      *Note: if using subselects for the 'table' value consider also
       passing the 'raster_field' and 'srid' and 'extent_from_subquery'
       options and/or specifying the 'raster_table' option.

    Optional db connection keyword arguments:
      user -- database user to connect as (default: see postgres docs)
      password -- password for database user (default: see postgres docs)
      host -- postgres hostname (default: see postgres docs)
      port -- postgres port (default: see postgres docs)
      initial_size -- integer size of connection pool (default: 1)
      max_size -- integer max of connection pool (default: 10)
      persist_connection -- keep connection open (default: True)

    Optional table-level keyword arguments:
      extent -- manually specified data extent (comma delimited string, default: None)
      estimate_extent -- boolean, direct PostGIS to use the faster, less accurate `estimate_extent` over `extent` (default: False)
      extent_from_subquery -- boolean, direct Mapnik to query Postgis for the extent of the raw 'table' value (default: uses 'geometry_table')
      raster_table -- specify geometry table to use to look up metadata (default: automatically parsed from 'table' value)
      raster_field -- specify geometry field to use (default: first entry in raster_columns)
      srid -- specify srid to use (default: auto-detected from geometry_field)
      row_limit -- integer limit of rows to return (default: 0)
      cursor_size -- integer size of binary cursor to use (default: 0, no binary cursor is used)
      use_overviews -- boolean, use overviews when available (default: false)
      prescale_rasters -- boolean, scale rasters on the db side (default: false)
      clip_rasters -- boolean, clip rasters on the db side (default: false)
      band -- integer, if non-zero interprets the given band (1-based offset) as a data raster (default: 0)

    >>> from mapnik import PgRaster, Layer
    >>> params = dict(dbname='mapnik',table='osm',user='postgres',password='gis')
    >>> params['estimate_extent'] = False
    >>> params['extent'] = '-20037508,-19929239,20037508,19929239'
    >>> pgraster = PgRaster(**params)
    >>> lyr = Layer('PgRaster Layer')
    >>> lyr.datasource = pgraster

    """
    keywords['type'] = 'pgraster'
    return CreateDatasource(keywords)


def Raster(**keywords):
    """Create a Raster (Tiff) Datasource.

    Required keyword arguments:
      file -- path to stripped or tiled tiff
      lox -- lowest (min) x/longitude of tiff extent
      loy -- lowest (min) y/latitude of tiff extent
      hix -- highest (max) x/longitude of tiff extent
      hiy -- highest (max) y/latitude of tiff extent

    Hint: lox,loy,hix,hiy make a Mapnik Box2d

    Optional keyword arguments:
      base -- path prefix (default None)
      multi -- whether the image is in tiles on disk (default False)

    Multi-tiled keyword arguments:
      x_width -- virtual image number of tiles in X direction (required)
      y_width -- virtual image number of tiles in Y direction (required)
      tile_size -- if an image is in tiles, how large are the tiles (default 256)
      tile_stride -- if an image is in tiles, what's the increment between rows/cols (default 1)

    >>> from mapnik import Raster, Layer
    >>> raster = Raster(base='/home/mapnik/data',file='elevation.tif',lox=-122.8,loy=48.5,hix=-122.7,hiy=48.6)
    >>> lyr = Layer('Tiff Layer')
    >>> lyr.datasource = raster

    """
    keywords['type'] = 'raster'
    return CreateDatasource(keywords)


def Gdal(**keywords):
    """Create a GDAL Raster Datasource.

    Required keyword arguments:
      file -- path to GDAL supported dataset

    Optional keyword arguments:
      base -- path prefix (default None)
      shared -- boolean, open GdalDataset in shared mode (default: False)
      bbox -- tuple (minx, miny, maxx, maxy). If specified, overrides the bbox detected by GDAL.

    >>> from mapnik import Gdal, Layer
    >>> dataset = Gdal(base='/home/mapnik/data',file='elevation.tif')
    >>> lyr = Layer('GDAL Layer from TIFF file')
    >>> lyr.datasource = dataset

    """
    keywords['type'] = 'gdal'
    if 'bbox' in keywords:
        if isinstance(keywords['bbox'], (tuple, list)):
            keywords['bbox'] = ','.join([str(item)
                                         for item in keywords['bbox']])
    return CreateDatasource(keywords)


def Occi(**keywords):
    """Create a Oracle Spatial (10g) Vector Datasource.

    Required keyword arguments:
      user -- database user to connect as
      password -- password for database user
      host -- oracle host to connect to (does not refer to SID in tsnames.ora)
      table -- table name or subselect query

    Optional keyword arguments:
      initial_size -- integer size of connection pool (default 1)
      max_size -- integer max of connection pool (default 10)
      extent -- manually specified data extent (comma delimited string, default None)
      estimate_extent -- boolean, direct Oracle to use the faster, less accurate estimate_extent() over extent() (default False)
      encoding -- file encoding (default 'utf-8')
      geometry_field -- specify geometry field (default 'GEOLOC')
      use_spatial_index -- boolean, force the use of the spatial index (default True)

    >>> from mapnik import Occi, Layer
    >>> params = dict(host='myoracle',user='scott',password='tiger',table='test')
    >>> params['estimate_extent'] = False
    >>> params['extent'] = '-20037508,-19929239,20037508,19929239'
    >>> oracle = Occi(**params)
    >>> lyr = Layer('Oracle Spatial Layer')
    >>> lyr.datasource = oracle
    """
    keywords['type'] = 'occi'
    return CreateDatasource(keywords)


def Ogr(**keywords):
    """Create a OGR Vector Datasource.

    Required keyword arguments:
      file -- path to OGR supported dataset
      layer -- name of layer to use within datasource (optional if layer_by_index or layer_by_sql is used)

    Optional keyword arguments:
      layer_by_index -- choose layer by index number instead of by layer name or sql.
      layer_by_sql -- choose layer by sql query number instead of by layer name or index.
      base -- path prefix (default None)
      encoding -- file encoding (default 'utf-8')

    >>> from mapnik import Ogr, Layer
    >>> datasource = Ogr(base='/home/mapnik/data',file='rivers.geojson',layer='OGRGeoJSON')
    >>> lyr = Layer('OGR Layer from GeoJSON file')
    >>> lyr.datasource = datasource

    """
    keywords['type'] = 'ogr'
    return CreateDatasource(keywords)


def SQLite(**keywords):
    """Create a SQLite Datasource.

    Required keyword arguments:
      file -- path to SQLite database file
      table -- table name or subselect query

    Optional keyword arguments:
      base -- path prefix (default None)
      encoding -- file encoding (default 'utf-8')
      extent -- manually specified data extent (comma delimited string, default None)
      metadata -- name of auxiliary table containing record for table with xmin, ymin, xmax, ymax, and f_table_name
      geometry_field -- name of geometry field (default 'the_geom')
      key_field -- name of primary key field (default 'OGC_FID')
      row_offset -- specify a custom integer row offset (default 0)
      row_limit -- specify a custom integer row limit (default 0)
      wkb_format -- specify a wkb type of 'spatialite' (default None)
      use_spatial_index -- boolean, instruct sqlite plugin to use Rtree spatial index (default True)

    >>> from mapnik import SQLite, Layer
    >>> sqlite = SQLite(base='/home/mapnik/data',file='osm.db',table='osm',extent='-20037508,-19929239,20037508,19929239')
    >>> lyr = Layer('SQLite Layer')
    >>> lyr.datasource = sqlite

    """
    keywords['type'] = 'sqlite'
    return CreateDatasource(keywords)


def Rasterlite(**keywords):
    """Create a Rasterlite Datasource.

    Required keyword arguments:
      file -- path to Rasterlite database file
      table -- table name or subselect query

    Optional keyword arguments:
      base -- path prefix (default None)
      extent -- manually specified data extent (comma delimited string, default None)

    >>> from mapnik import Rasterlite, Layer
    >>> rasterlite = Rasterlite(base='/home/mapnik/data',file='osm.db',table='osm',extent='-20037508,-19929239,20037508,19929239')
    >>> lyr = Layer('Rasterlite Layer')
    >>> lyr.datasource = rasterlite

    """
    keywords['type'] = 'rasterlite'
    return CreateDatasource(keywords)


def Osm(**keywords):
    """Create a Osm Datasource.

    Required keyword arguments:
      file -- path to OSM file

    Optional keyword arguments:
      encoding -- file encoding (default 'utf-8')
      url -- url to fetch data (default None)
      bbox -- data bounding box for fetching data (default None)

    >>> from mapnik import Osm, Layer
    >>> datasource = Osm(file='test.osm')
    >>> lyr = Layer('Osm Layer')
    >>> lyr.datasource = datasource

    """
    # note: parser only supports libxml2 so not exposing option
    # parser -- xml parser to use (default libxml2)
    keywords['type'] = 'osm'
    return CreateDatasource(keywords)


def Python(**keywords):
    """Create a Python Datasource.

    >>> from mapnik import Python, PythonDatasource
    >>> datasource = Python('PythonDataSource')
    >>> lyr = Layer('Python datasource')
    >>> lyr.datasource = datasource
    """
    keywords['type'] = 'python'
    return CreateDatasource(keywords)


def MemoryDatasource(**keywords):
    """Create a Memory Datasource.

    Optional keyword arguments:
        (TODO)
    """
    params = Parameters()
    params.append(Parameter('type', 'memory'))
    return MemoryDatasourceBase(params)


class PythonDatasource(object):
    """A base class for a Python data source.

    Optional arguments:
      envelope -- a mapnik.Box2d (minx, miny, maxx, maxy) envelope of the data source, default (-180,-90,180,90)
      geometry_type -- one of the DataGeometryType enumeration values, default Point
      data_type -- one of the DataType enumerations, default Vector
    """

    def __init__(self, envelope=None, geometry_type=None, data_type=None):
        self.envelope = envelope or Box2d(-180, -90, 180, 90)
        self.geometry_type = geometry_type or DataGeometryType.Point
        self.data_type = data_type or DataType.Vector

    def features(self, query):
        """Return an iterable which yields instances of Feature for features within the passed query.

        Required arguments:
          query -- a Query instance specifying the region for which features should be returned
        """
        return None

    def features_at_point(self, point):
        """Rarely used. Return an iterable which yields instances of Feature for the specified point."""
        return None

    @classmethod
    def wkb_features(cls, keys, features):
        """A convenience function to wrap an iterator yielding pairs of WKB format geometry and dictionaries of
        key-value pairs into mapnik features. Return this from PythonDatasource.features() passing it a sequence of keys
        to appear in the output and an iterator yielding features.

        For example. One might have a features() method in a derived class like the following:

        def features(self, query):
            # ... create WKB features feat1 and feat2

            return mapnik.PythonDatasource.wkb_features(
                keys = ( 'name', 'author' ),
                features = [
                    (feat1, { 'name': 'feat1', 'author': 'alice' }),
                    (feat2, { 'name': 'feat2', 'author': 'bob' }),
                ]
            )

        """
        ctx = Context()
        [ctx.push(x) for x in keys]

        def make_it(feat, idx):
            f = Feature(ctx, idx)
            geom, attrs = feat
            f.add_geometries_from_wkb(geom)
            for k, v in attrs.iteritems():
                f[k] = v
            return f

        return itertools.imap(make_it, features, itertools.count(1))

    @classmethod
    def wkt_features(cls, keys, features):
        """A convenience function to wrap an iterator yielding pairs of WKT format geometry and dictionaries of
        key-value pairs into mapnik features. Return this from PythonDatasource.features() passing it a sequence of keys
        to appear in the output and an iterator yielding features.

        For example. One might have a features() method in a derived class like the following:

        def features(self, query):
            # ... create WKT features feat1 and feat2

            return mapnik.PythonDatasource.wkt_features(
                keys = ( 'name', 'author' ),
                features = [
                    (feat1, { 'name': 'feat1', 'author': 'alice' }),
                    (feat2, { 'name': 'feat2', 'author': 'bob' }),
                ]
            )

        """
        ctx = Context()
        [ctx.push(x) for x in keys]

        def make_it(feat, idx):
            f = Feature(ctx, idx)
            geom, attrs = feat
            f.add_geometries_from_wkt(geom)
            for k, v in attrs.iteritems():
                f[k] = v
            return f

        return itertools.imap(make_it, features, itertools.count(1))


class _TextSymbolizer(TextSymbolizer, _injector):

    @property
    def name(self):
        if isinstance(self.properties.format_tree, FormattingText):
            return self.properties.format_tree.text
        else:
            # There is no single expression which could be returned as name
            raise RuntimeError(
                "TextSymbolizer uses complex formatting features, but old compatibility interface is used to access it. Use self.properties.format_tree instead.")

    @name.setter
    def name(self, name):
        self.properties.format_tree = FormattingText(name)

    @property
    def text_size(self):
        return self.format.text_size

    @text_size.setter
    def text_size(self, text_size):
        self.format.text_size = text_size

    @property
    def face_name(self):
        return self.format.face_name

    @face_name.setter
    def face_name(self, face_name):
        self.format.face_name = face_name

    @property
    def fontset(self):
        return self.format.fontset

    @fontset.setter
    def fontset(self, fontset):
        self.format.fontset = fontset

    @property
    def character_spacing(self):
        return self.format.character_spacing

    @character_spacing.setter
    def character_spacing(self, character_spacing):
        self.format.character_spacing = character_spacing

    @property
    def line_spacing(self):
        return self.format.line_spacing

    @line_spacing.setter
    def line_spacing(self, line_spacing):
        self.format.line_spacing = line_spacing

    @property
    def text_opacity(self):
        return self.format.text_opacity

    @text_opacity.setter
    def text_opacity(self, text_opacity):
        self.format.text_opacity = text_opacity

    @property
    def wrap_before(self):
        return self.format.wrap_before

    @wrap_before.setter
    def wrap_before(self, wrap_before):
        self.format.wrap_before = wrap_before

    @property
    def text_transform(self):
        return self.format.text_transform

    @text_transform.setter
    def text_transform(self, text_transform):
        self.format.text_transform = text_transform

    @property
    def fill(self):
        return self.format.fill

    @fill.setter
    def fill(self, fill):
        self.format.fill = fill

    @property
    def halo_fill(self):
        return self.format.halo_fill

    @halo_fill.setter
    def halo_fill(self, halo_fill):
        self.format.halo_fill = halo_fill

    @property
    def halo_radius(self):
        return self.format.halo_radius

    @halo_radius.setter
    def halo_radius(self, halo_radius):
        self.format.halo_radius = halo_radius

    @property
    def label_placement(self):
        return self.properties.label_placement

    @label_placement.setter
    def label_placement(self, label_placement):
        self.properties.label_placement = label_placement

    @property
    def horizontal_alignment(self):
        return self.properties.horizontal_alignment

    @horizontal_alignment.setter
    def horizontal_alignment(self, horizontal_alignment):
        self.properties.horizontal_alignment = horizontal_alignment

    @property
    def justify_alignment(self):
        return self.properties.justify_alignment

    @justify_alignment.setter
    def justify_alignment(self, justify_alignment):
        self.properties.justify_alignment = justify_alignment

    @property
    def vertical_alignment(self):
        return self.properties.vertical_alignment

    @vertical_alignment.setter
    def vertical_alignment(self, vertical_alignment):
        self.properties.vertical_alignment = vertical_alignment

    @property
    def orientation(self):
        return self.properties.orientation

    @orientation.setter
    def orientation(self, orientation):
        self.properties.orientation = orientation

    @property
    def displacement(self):
        return self.properties.displacement

    @displacement.setter
    def displacement(self, displacement):
        self.properties.displacement = displacement

    @property
    def label_spacing(self):
        return self.properties.label_spacing

    @label_spacing.setter
    def label_spacing(self, label_spacing):
        self.properties.label_spacing = label_spacing

    @property
    def label_position_tolerance(self):
        return self.properties.label_position_tolerance

    @label_position_tolerance.setter
    def label_position_tolerance(self, label_position_tolerance):
        self.properties.label_position_tolerance = label_position_tolerance

    @property
    def avoid_edges(self):
        return self.properties.avoid_edges

    @avoid_edges.setter
    def avoid_edges(self, avoid_edges):
        self.properties.avoid_edges = avoid_edges

    @property
    def minimum_distance(self):
        return self.properties.minimum_distance

    @minimum_distance.setter
    def minimum_distance(self, minimum_distance):
        self.properties.minimum_distance = minimum_distance

    @property
    def minimum_padding(self):
        return self.properties.minimum_padding

    @minimum_padding.setter
    def minimum_padding(self, minimum_padding):
        self.properties.minimum_padding = minimum_padding

    @property
    def minimum_path_length(self):
        return self.properties.minimum_path_length

    @minimum_path_length.setter
    def minimum_path_length(self, minimum_path_length):
        self.properties.minimum_path_length = minimum_path_length

    @property
    def maximum_angle_char_delta(self):
        return self.properties.maximum_angle_char_delta

    @maximum_angle_char_delta.setter
    def maximum_angle_char_delta(self, maximum_angle_char_delta):
        self.properties.maximum_angle_char_delta = maximum_angle_char_delta

    @property
    def allow_overlap(self):
        return self.properties.allow_overlap

    @allow_overlap.setter
    def allow_overlap(self, allow_overlap):
        self.properties.allow_overlap = allow_overlap

    @property
    def text_ratio(self):
        return self.properties.text_ratio

    @text_ratio.setter
    def text_ratio(self, text_ratio):
        self.properties.text_ratio = text_ratio

    @property
    def wrap_width(self):
        return self.properties.wrap_width

    @wrap_width.setter
    def wrap_width(self, wrap_width):
        self.properties.wrap_width = wrap_width


def mapnik_version_from_string(version_string):
    """Return the Mapnik version from a string."""
    n = version_string.split('.')
    return (int(n[0]) * 100000) + (int(n[1]) * 100) + (int(n[2]))


def register_plugins(path=None):
    """Register plugins located by specified path"""
    if not path:
        if 'MAPNIK_INPUT_PLUGINS_DIRECTORY' in os.environ:
            path = os.environ.get('MAPNIK_INPUT_PLUGINS_DIRECTORY')
        else:
            from .paths import inputpluginspath
            path = inputpluginspath
    DatasourceCache.register_datasources(path)


def register_fonts(path=None, valid_extensions=[
                   '.ttf', '.otf', '.ttc', '.pfa', '.pfb', '.ttc', '.dfont', '.woff']):
    """Recursively register fonts using path argument as base directory"""
    if not path:
        if 'MAPNIK_FONT_DIRECTORY' in os.environ:
            path = os.environ.get('MAPNIK_FONT_DIRECTORY')
        else:
            from .paths import fontscollectionpath
            path = fontscollectionpath
    for dirpath, _, filenames in os.walk(path):
        for filename in filenames:
            if os.path.splitext(filename.lower())[1] in valid_extensions:
                FontEngine.instance().register_font(os.path.join(dirpath, filename))

# auto-register known plugins and fonts
register_plugins()
register_fonts()