ZVV Tarifzonen KML (Google Maps)

zvv2kml.py

#!/usr/bin/env python

# Fetch ZVV Tarifzonen map in SVG and convert to KML.
# You can save the output and import into Google Maps.
# Use at your own risk. The API used is not publicly disclosed,
# improper use may lead to lawsuits.

import sys
import urllib2
import xml.etree.ElementTree as ET

minLat = 47.1417
maxLat = 47.7124
minLon = 8.15723
maxLon = 9.03749

width = 2000
height = 2000

url = 'http://wms.zh.ch/ZVVZHWMS?version=1.3.0&service=WMS&request=GetMap&' \
        'LAYERS=tarifzonen&format=image/svg%%2Bxml&CRS=EPSG:4326&BBOX=' \
        '%.5f,%.5f,%.5f,%.5f&WIDTH=%d&HEIGHT=%d' % (
                minLat, minLon, maxLat, maxLon, width, height)

root = ET.fromstring(urllib2.urlopen(url).read())

def ParseColor(s):
    if s.startswith('rgb'):
        return ''.join(
                '%.2x' % (float(percent[:-1]) * 0xff / 100)
                for percent in reversed(s[4:-1].split(',')))
    return '000000'

def ParseData(s):
    pipeline = s.split(' ')
    moveto = None
    for i in xrange(0, len(pipeline), 3):
        command, x, y = pipeline[i:i+3]
        if command == 'L':
            if moveto:
                yield moveto
                moveto = None
            yield (x, y)
        elif command == 'M':
            moveto = (x, y)
        elif command == 'Z':
            return
        else:
            raise Exception('Unknown command: %s' % command)

def Map(value, low, high, newLow, newHigh):
    return (value - low) / (high - low) * (newHigh - newLow) + newLow

def AddStyle(doc, styleId, fill):
    style = ET.SubElement(doc, 'Style', id=styleId)
    poly = ET.SubElement(style, 'PolyStyle')
    ET.SubElement(poly, 'color').text = fill
    ET.SubElement(poly, 'fill').text = '1'
    ET.SubElement(poly, 'outline').text = '1'

kml = ET.Element('kml', xmlns='http://www.opengis.net/kml/2.2')
doc = ET.SubElement(kml, 'Document')
ET.SubElement(doc, 'name').text='Tarifzonen'

for i, path in enumerate(root.iter('{http://www.w3.org/2000/svg}path')):
    styles = dict(
            style.split(':')
            for style in  path.attrib['style'].split(';')
            if len(style))
    if (styles.get('fill') == 'none') or (styles.get('fill-opacity') == '1'):
        # These are numbers, we don't have curve support so don't even try
        continue

    pm = ET.SubElement(doc, 'Placemark')
    ET.SubElement(pm, 'name').text = str(i)
    ET.SubElement(pm, 'styleUrl').text = '#poly-%d' % i
    ring = ET.SubElement(
            ET.SubElement(
                ET.SubElement(pm, 'Polygon'),
                'outerBoundaryIs'),
            'LinearRing')
    ET.SubElement(ring, 'tessellate').text = '1'
    try:
        coordinates = [
                (Map(float(x), 0, width, minLon, maxLon),
                    Map(float(y), 0, height, maxLat, minLat))
                for x, y in ParseData(path.attrib['d'])]
    except:
        continue
    ET.SubElement(ring, 'coordinates').text = ' '.join('%.8f,%.8f,0.0' % (x, y)
            for x, y in coordinates)

    # fill is AABBGGRR, where AA is alpha-channel (transparency)
    fill = '%.2x%s' % (
            int(float(styles.get('fill-opacity', 1)) * 0xff),
            ParseColor(styles['fill']))
    AddStyle(doc, 'poly-%d' % i, fill)

ET.ElementTree(kml).write(sys.stdout, encoding='utf-8', xml_declaration=True)