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-- Universal Product Code
-- UPC family barcode generator
--
-- Copyright (C) 2019-2022 Roberto Giacomelli
-- see LICENSE.txt file
local UPC = {
_VERSION = "upc v0.0.2",
_NAME = "upc",
_DESCRIPTION = "UPC barcode encoder",
}
UPC._pattern = {[0] = 3211, 2221, 2122, 1411, 1132, 1231, 1114, 1312, 1213, 3112,}
UPC._sepbar = 111
UPC._id_variant = {
A = true, -- UPC-A
}
-- common family parameters
UPC._par_order = {
"mod",
"height",
"bars_depth_factor",
"quietzone_factor",
"text_enabled",
"text_ygap_factor",
"text_xgap_factor",
}
UPC._par_def = {}
local pardef = UPC._par_def
-- from Wikipedia https://en.wikipedia.org/wiki/Universal_Product_Code
-- The x-dimension for the UPC-A at the nominal size is 0.33 mm (0.013").
-- UPC-A can be reduced or magnified anywhere from 80% to 200%.
-- standard module is 0.33 mm but it may vary from 0.264 to 0.66mm
pardef.mod = {
default = 0.33 * 186467, -- (mm to sp) X dimension (original value 0.33)
unit = "sp", -- scaled point
isReserved = true,
fncheck = function (_self, x, _) --> boolean, err
local mm = 186467
local min, max = 0.264*mm, 0.660*mm
if x < min then
return false, "[OutOfRange] too small value for mod"
elseif x > max then
return false, "[OutOfRange] too big value for mod"
end
return true, nil
end,
}
-- Nominal symbol height for UPC-A is 25.9 mm (1.02")
pardef.height = {
default = 25.9 * 186467,
unit = "sp",
isReserved = false,
fncheck = function (self, h, _enc) --> boolean, err
if h > 0 then
return true, nil
else
return false, "[OutOfRange] non positive value for height"
end
end,
}
-- The bars forming the S (start), M (middle), and E (end) guard patterns, are
-- extended downwards by 5 times x-dimension, with a resulting nominal symbol
-- height of 27.55 mm (1.08")
pardef.bars_depth_factor = {
default = 5,
unit = "absolute-number",
isReserved = false,
fncheck = function (_self, b, _) --> boolean, err
if b >= 0 then
return true, nil
else
return false, "[OutOfRange] non positive value for bars_depth_factor"
end
end,
}
-- A quiet zone, with a width of at least 9 times the x-dimension, must be
-- present on each side of the scannable area of the UPC-A barcode.
pardef.quietzone_factor = {
default = 9,
unit = "absolute-number",
isReserved = false,
fncheck = function (_self, qzf, _) --> boolean, err
if qzf > 0 then
return true, nil
else
return false, "[OutOfRange] non positive value for quietzone_right_factor"
end
end,
}
-- enable/disable human readble text
pardef.text_enabled = { -- boolean type
default = true,
isReserved = false,
fncheck = function (_self, flag, _) --> boolean, err
if type(flag) == "boolean" then
return true, nil
else
return false, "[TypeErr] not a boolean value for text_enabled"
end
end,
}
-- vertical gap from text and symbol baseline
pardef.text_ygap_factor = {
default = 1.0,
unit = "absolute-number",
isReserved = false,
fncheck = function (_self, t, _) --> boolean, err
if t >= 0 then
return true, nil
else
return false, "[OutOfRange] non positive value for text_ygap_factor"
end
end,
}
-- horizontal gap from text and symbol bars
pardef.text_xgap_factor = {
default = 0.75,
unit = "absolute-number",
isReserved = false,
fncheck = function (_self, t, _) --> boolean, err
if t >= 0 then
return true, nil
else
return false, "[OutOfRange] non positive value for text_xgap_factor"
end
end,
}
-- utility function
-- the checksum of UPC-A
-- 'data' is an array of digits
local function checkdigit_A(data) --> checksum, ok
local s = 0
for i = 1, 11, 2 do
s = s + data[i]
end
s = 3*s
for i = 2, 10, 2 do
s = s + data[i]
end
local res = s % 10
if res > 0 then
res = 10 - res
end
return res, data[12] == res
end
-- internal methods for Barcode costructors
-- config function called at the moment of encoder construction
function UPC:_config() --> ok, err
local variant = self._variant
if not variant then
return false, "[Err] variant is mandatory for the UPC family"
end
local Vbar = self._libgeo.Vbar -- Vbar class
local Vbar_archive = self._libgeo.Archive -- Archive class
local Codeset = Vbar_archive:new()
self._upca_codeset = Codeset
local mod = self.mod
local sepbar = self._sepbar
Codeset:insert(Vbar:from_int(sepbar, mod), "sepbar")
local symb = self._pattern
for i = 0, 9 do
Codeset:insert(Vbar:from_int(symb[i], mod, false), 0, i)
Codeset:insert(Vbar:from_int(symb[i], mod, true), 1, i)
end
return true, nil
end
-- function called every time an input UPC-A code has been completely parsed
function UPC:_finalize() --> ok, err
local data = self._code_data
local symb_len = #data
if symb_len ~= 12 then
return false, "[ArgErr] not a 12-digit long array"
end
local ck, ok = checkdigit_A(data)
if not ok then -- is the last digit ok?
return false,
"[Err] incorrect last digit "..data[12]..", the checksum is "..ck
end
return true, nil
end
-- Drawing into the provided channel geometrical data
-- tx, ty is the optional translation vector
-- the function return the canvas reference to allow call chaining
function UPC:_append_ga(canvas, tx, ty) --> bbox
local Codeset = self._upca_codeset
local code = self._code_data
local mod = self.mod
local sepbar = assert(Codeset:get("sepbar"))
local queue_0 = sepbar + assert(Codeset:get(0, code[1])) +
36*mod + sepbar + 36*mod +
assert(Codeset:get(1, code[12])) + sepbar
local queue_1 = 10*mod
for i = 2, 6 do
queue_1 = queue_1 + assert(Codeset:get(0, code[i]))
end
queue_1 = queue_1 + 5*mod
for i = 7, 11 do
queue_1 = queue_1 + assert(Codeset:get(1, code[i]))
end
local bars_depth = mod * self.bars_depth_factor
local w, h = 95*mod, self.height + bars_depth
local x0 = tx - self.ax * w
local y0 = ty - self.ay * h
local x1 = x0 + w
local y1 = y0 + h
local ys = y0 + bars_depth
-- draw the symbol
assert(canvas:encode_disable_bbox())
assert(canvas:encode_vbar_queue(queue_0, x0, y0, y1))
assert(canvas:encode_vbar_queue(queue_1, x0, ys, y1))
-- bounding box set up
local qz = self.quietzone_factor * mod
assert(canvas:encode_set_bbox(x0 - qz, y0, x1 + qz, y1))
assert(canvas:encode_enable_bbox())
if self.text_enabled then -- human readable text
local Text = self._libgeo.Text
local txt_1 = Text:from_digit_array(code, 1, 1)
local txt_2 = Text:from_digit_array(code, 2, 6)
local txt_3 = Text:from_digit_array(code, 7, 11)
local txt_4 = Text:from_digit_array(code, 12, 12)
local y_bl = ys - self.text_ygap_factor * mod
assert(canvas:encode_Text(txt_1, x0 - qz, y_bl, 0, 1))
local mx = self.text_xgap_factor
local x2_1 = x0 + (10+mx)*mod
local x2_2 = x0 + (46-mx)*mod
assert(canvas:encode_Text_xwidth(txt_2, x2_1, x2_2, y_bl, 1))
local x3_1 = x0 + (49+mx)*mod
local x3_2 = x0 + (85-mx)*mod
assert(canvas:encode_Text_xwidth(txt_3, x3_1, x3_2, y_bl, 1))
assert(canvas:encode_Text(txt_4, x1 + qz, y_bl, 1, 1))
end
return {x0, y0, x1, y1, qz, nil, qz, nil,}
end
return UPC
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