#!/usr/bin/python
# -*- coding: utf8 -*-

try:
    import svgwrite as svg
except ImportError:
    print 'requires svgwrite library: http://pypi.python.org/pypi/svgwrite/'
    exit(1)


name = 'Cylindrical_magnet'
w, h = 616, 216
lw = 16
l, r = (w - lw) / 2., (h - lw) / 2.


# document
doc = svg.Drawing(name + '.svg', size=(w, h))
doc.set_desc(title=name,
    desc='about: http://commons.wikimedia.org/wiki/File:{0}.svg'.format(name))
doc['stroke'] = 'black'
doc['stroke-linejoin'] = 'miter'


magnet = doc.add(doc.g(id='magnet', transform='translate({0},{1})'.format(w/2., h/2.)))


# green and red areas
magnet.add(doc.rect(insert=(-l, -r), size=(2*l, 2*r),
    fill='#00cc00', stroke='none'))
magnet.add(doc.rect(insert=(0, -r), size=(l, 2*r),
    fill='#ff0000', stroke='none'))


# light reflection gradient overlay
grad = doc.defs.add(doc.linearGradient(id='gradient',
    x1=0, x2=0, y1=-r, y2=r, gradientUnits='userSpaceOnUse'))
for col, of, opa in [['#000000', '0', '0.125'],
    ['#ffffff', '0.07', '0.125'], ['#ffffff', '0.25', '0.5'],
    ['#ffffff', '0.6', '0.2'], ['#000000', '1', '0.33']]:
    grad.add_stop_color(offset=of, color=col, opacity=opa)


# frame
magnet.add(doc.rect(insert=(-l, -r), size=(2*l, 2*r),
    style='fill:url(#gradient); stroke-width:{0}; stroke-linejoin:miter; stroke:#000000'.format(lw)))


# S and N labels
S = doc.text('S', insert=(0, 0),
        transform='translate({0},{1}) scale({2},{2})'.format(
        -0.65 * l, 0.44 * r, r / 100.))
N = doc.text('N', insert=(0, 0),
        transform='translate({0},{1}) scale({2},{2})'.format(
        0.65 * l, 0.44 * r, r / 100.))
text_attr = {'text-anchor':'middle',
    'style':'fill:#000000; stroke:none; ' +
    'font-size:120px; font-family:Bitstream Vera Sans'}
for k, v in text_attr.iteritems():
    S[k] = v
    N[k] = v
magnet.add(S)
magnet.add(N)


doc.save()
try:
    import xml.dom.minidom
    xml = xml.dom.minidom.parse(name + '.svg')
    with open(name + '.svg', 'w') as svg_file:
        svg_file.write(xml.toprettyxml(indent='  '))
except ImportError: pass