A simple tile maker, using mapnik and mercantile

01_tilemaker.py

"""
requires:
    - mapnik 3.x and its python bindings (https://github.com/mapnik/mapnik)
    - mercantile==0.9.0 (https://github.com/mapbox/mercantile)
"""

import os

import mapnik
import mercantile

TILE_WIDTH = 256


class TileMaker(object):
    def __init__(self, extent, zooms, xml_data, output=os.curdir, overwrite_existing_tiles=False):
        """
        Creates 256x256 tiles in `output` for the passed extent and zoom levels
        :param extent: is a list of coordinates for the working area [west, south, east, north]
        :param zooms: a list of zoom levels to make tiles for
        :param xml_data: mapnik xml styling; can be either inline data or the path to an xml file
        :param output: is the folder to save the tiles in; default is the current working directory
        :param overwrite_existing_tiles: whether to overwrite existing tile or not
        """
        tiles = mercantile.tiles(*extent, zooms)

        m = mapnik.Map(TILE_WIDTH, TILE_WIDTH)
        m.aspect_fix_mode = mapnik.aspect_fix_mode.RESPECT
        
        if xml_data.endswith('.xml'):
            mapnik.load_map(m, xml_data)
        else:
            mapnik.load_map_from_string(m, xml_data)

        for t in tiles:
            bound = mercantile.bounds(t)

            cwd = os.path.join(output, '{z}/{x}'.format(z=t.z, x=t.x))
            if not os.path.exists(cwd):
                os.makedirs(cwd)

            tile_path = os.path.join(cwd, '{y}.png'.format(y=t.y))
            if not overwrite_existing_tiles and os.path.exists(tile_path):
                continue

            box = mapnik.Box2d(*bound)
            m.zoom_to_box(box)
            mapnik.render_to_file(m, tile_path)

            print('created {}'.format(tile_path))

        print('Your tiles are in {}!'.format(output))


if __name__ == '__main__':
    TileMaker([-125.865224875, 30.970478609, -112.681631125, 43.577740391], range(5, 10), '02_sample.xml', 'tiles', False)

02_sample.xml

<Map srs="+proj=longlat +ellps=WGS84 +datum=WGS84">
    <Style name="style">
        <Rule>
            <Filter>[col_name] &lt;= -0.75</Filter>
            <PolygonSymbolizer fill="#444f89" gamma="0"/>
        </Rule>
        <Rule>
            <Filter>[col_name] &gt; -0.75 and [col_name] &lt;= -0.5</Filter>
            <PolygonSymbolizer fill="#9eaad7" gamma="0"/>
        </Rule>
        <Rule>
            <Filter>[col_name] &gt; -0.5 and [col_name] &lt;= 0</Filter>
            <PolygonSymbolizer fill="#ffffbe" gamma="0"/>
        </Rule>
        <Rule>
            <Filter>[col_name] &gt; 0 and [col_name] &lt;= 0.5</Filter>
            <PolygonSymbolizer fill="#bfd67b" gamma="0"/>
        </Rule>
        <Rule>
            <Filter>[col_name] &gt; 0.5 and [col_name] &lt;= 0.75</Filter>
            <PolygonSymbolizer fill="#7f9a51" gamma="0"/>
        </Rule>
        <Rule>
            <Filter>[col_name] &gt; 0.75</Filter>
            <PolygonSymbolizer fill="#364d22" gamma="0"/>
        </Rule>
    </Style>

    <Layer name="connectivity" srs="+proj=longlat +ellps=WGS84 +datum=WGS84">
        <StyleName>style</StyleName>
        <Datasource>
          <Parameter name="type">postgis</Parameter>
          <Parameter name="host">localhost</Parameter>
          <Parameter name="port">5432</Parameter>
          <Parameter name="dbname">spatial_db</Parameter>
          <Parameter name="user">db_user</Parameter>
          <Parameter name="password">top_secret</Parameter>
          <Parameter name="table">spatial_table</Parameter>
        </Datasource>
    </Layer>
</Map>