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# coding=utf-8
#
# Copyright (C) 2010 Martin Owens
#
# This program 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
# (at your option) 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA.
#
"""
Base module for rendering barcodes for Inkscape.
"""
import itertools
import sys
from inkex import Group, TextElement, Rectangle
(TEXT_POS_BOTTOM, TEXT_POS_TOP) = range(2)
(WHITE_BAR, BLACK_BAR, TALL_BAR) = range(3)
TEXT_TEMPLATE = 'font-size:%dpx;text-align:center;text-anchor:middle;'
try:
from typing import Optional
except ImportError:
pass
class Barcode(object):
"""Provide a base class for all barcode renderers"""
default_height = 30
font_size = 9
name = None # type: Optional[str]
def error(self, text, msg):
"""Cause an error to be reported"""
sys.stderr.write(
"Error encoding '{}' as {} barcode: {}\n".format(text, self.name, msg))
return "ERROR"
def encode(self, text):
"""
Replace this with the encoding function, it should return
a string of ones and zeros
"""
raise NotImplementedError("You need to write an encode() function.")
def __init__(self, param):
param = param or {}
self.document = param.get('document', None)
self.known_ids = []
self._extra = []
self.pos_x = int(param.get('x', 0))
self.pos_y = int(param.get('y', 0))
self.text = param.get('text', None)
self.scale = param.get('scale', 1)
self.height = param.get('height', self.default_height)
self.pos_text = param.get('text_pos', TEXT_POS_BOTTOM)
if self.document:
self.known_ids = list(self.document.xpath('//@id'))
if not self.text:
raise ValueError("No string specified for barcode.")
def get_id(self, name='element'):
"""Get the next useful id (and claim it)"""
index = 0
while name in self.known_ids:
index += 1
name = 'barcode{:d}'.format(index)
self.known_ids.append(name)
return name
def add_extra_barcode(self, barcode, **kw):
"""Add an extra barcode along side this one, used for ean13 extras"""
from . import get_barcode
kw['height'] = self.height
kw['document'] = self.document
kw['scale'] = None
self._extra.append(get_barcode(barcode, **kw).generate())
def generate(self):
"""Generate the actual svg from the coding"""
string = self.encode(self.text)
if string == 'ERROR':
return
name = self.get_id('barcode')
# use an svg group element to contain the barcode
barcode = Group()
barcode.set('id', name)
barcode.set('style', 'fill: black;')
barcode.transform.add_translate(self.pos_x, self.pos_y)
if self.scale:
barcode.transform.add_scale(self.scale)
bar_id = 1
bar_offset = 0
tops = set()
for datum in self.graphical_array(string):
# Datum 0 tells us what style of bar is to come next
style = self.get_style(int(datum[0]))
# Datum 1 tells us what width in units,
# style tells us how wide a unit is
width = int(datum[1]) * int(style['width'])
if style['write']:
tops.add(style['top'])
rect = Rectangle()
rect.set('x', str(bar_offset))
rect.set('y', str(style['top']))
if self.pos_text == TEXT_POS_TOP:
rect.set('y', str(style['top'] + self.font_size))
rect.set('id', "{}_bar{:d}".format(name, bar_id))
rect.set('width', str(width))
rect.set('height', str(style['height']))
barcode.append(rect)
bar_offset += width
bar_id += 1
for extra in self._extra:
if extra is not None:
barcode.append(extra)
bar_width = bar_offset
# Add text at the bottom of the barcode
text = TextElement()
text.set('x', str(int(bar_width / 2)))
text.set('y', str(min(tops) + self.font_size - 1))
if self.pos_text == TEXT_POS_BOTTOM:
text.set('y', str(self.height + max(tops) + self.font_size))
text.set('style', TEXT_TEMPLATE % self.font_size)
text.set('xml:space', 'preserve')
text.set('id', '{}_text'.format(name))
text.text = str(self.text)
barcode.append(text)
return barcode
def graphical_array(self, code):
"""Converts black and white markets into a space array"""
return [(x, len(list(y))) for x, y in itertools.groupby(code)]
def get_style(self, index):
"""Returns the styles that should be applied to each bar"""
result = {'width': 1, 'top': 0, 'write': True}
if index == BLACK_BAR:
result['height'] = int(self.height)
if index == TALL_BAR:
result['height'] = int(self.height) + int(self.font_size / 2)
if index == WHITE_BAR:
result['write'] = False
return result
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