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Diffstat (limited to 'share/extensions/barcode/Base.py')
| -rw-r--r-- | share/extensions/barcode/Base.py | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/share/extensions/barcode/Base.py b/share/extensions/barcode/Base.py new file mode 100644 index 0000000..024213c --- /dev/null +++ b/share/extensions/barcode/Base.py @@ -0,0 +1,171 @@ +# 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 +from inkex.localization import inkex_gettext as _ + +(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 |