A Code 128 barcode visualization that encodes alphanumeric data into a high-density linear barcode pattern. Code 128 is a widely-used 1D barcode format that supports the full 128 ASCII character set, with three code subsets (A, B, C) that can be switched dynamically for optimal encoding efficiency. This visualization generates scannable barcodes commonly found on shipping labels, industrial parts, and healthcare specimens.
""" anyplot.ai
barcode-code128: Code 128 Barcode
Library: matplotlib 3.10.9 | Python 3.13.13
Quality: 86/100 | Updated: 2026-05-21
"""
import os
import sys
sys.path = sys.path[1:] # prevent this file from shadowing the installed matplotlib package
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.colors import LinearSegmentedColormap
# Theme tokens
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
# Code 128B encoding: each character → 6 bar/space widths (alternating)
CODE128_B = {
" ": [2, 1, 2, 2, 2, 2],
"!": [2, 2, 2, 1, 2, 2],
'"': [2, 2, 2, 2, 2, 1],
"#": [1, 2, 1, 2, 2, 3],
"$": [1, 2, 1, 3, 2, 2],
"%": [1, 3, 1, 2, 2, 2],
"&": [1, 2, 2, 2, 1, 3],
"'": [1, 2, 2, 3, 1, 2],
"(": [1, 3, 2, 2, 1, 2],
")": [2, 2, 1, 2, 1, 3],
"*": [2, 2, 1, 3, 1, 2],
"+": [2, 3, 1, 2, 1, 2],
",": [1, 1, 2, 2, 3, 2],
"-": [1, 2, 2, 1, 3, 2],
".": [1, 2, 2, 2, 3, 1],
"/": [1, 1, 3, 2, 2, 2],
"0": [1, 2, 3, 1, 2, 2],
"1": [1, 2, 3, 2, 2, 1],
"2": [2, 2, 3, 2, 1, 1],
"3": [2, 2, 1, 1, 3, 2],
"4": [2, 2, 1, 2, 3, 1],
"5": [2, 1, 3, 2, 1, 2],
"6": [2, 2, 3, 1, 1, 2],
"7": [3, 1, 2, 1, 3, 1],
"8": [3, 1, 1, 2, 2, 2],
"9": [3, 2, 1, 1, 2, 2],
":": [3, 2, 1, 2, 2, 1],
";": [3, 1, 2, 2, 1, 2],
"<": [3, 2, 2, 1, 1, 2],
"=": [3, 2, 2, 2, 1, 1],
">": [2, 1, 2, 1, 2, 3],
"?": [2, 1, 2, 3, 2, 1],
"@": [2, 3, 2, 1, 2, 1],
"A": [1, 1, 1, 3, 2, 3],
"B": [1, 3, 1, 1, 2, 3],
"C": [1, 3, 1, 3, 2, 1],
"D": [1, 1, 2, 3, 1, 3],
"E": [1, 3, 2, 1, 1, 3],
"F": [1, 3, 2, 3, 1, 1],
"G": [2, 1, 1, 3, 1, 3],
"H": [2, 3, 1, 1, 1, 3],
"I": [2, 3, 1, 3, 1, 1],
"J": [1, 1, 2, 1, 3, 3],
"K": [1, 1, 2, 3, 3, 1],
"L": [1, 3, 2, 1, 3, 1],
"M": [1, 1, 3, 1, 2, 3],
"N": [1, 1, 3, 3, 2, 1],
"O": [1, 3, 3, 1, 2, 1],
"P": [3, 1, 3, 1, 2, 1],
"Q": [2, 1, 1, 3, 3, 1],
"R": [2, 3, 1, 1, 3, 1],
"S": [2, 1, 3, 1, 1, 3],
"T": [2, 1, 3, 3, 1, 1],
"U": [2, 1, 3, 1, 3, 1],
"V": [3, 1, 1, 1, 2, 3],
"W": [3, 1, 1, 3, 2, 1],
"X": [3, 3, 1, 1, 2, 1],
"Y": [3, 1, 2, 1, 1, 3],
"Z": [3, 1, 2, 3, 1, 1],
"[": [3, 3, 2, 1, 1, 1],
"\\": [3, 1, 4, 1, 1, 1],
"]": [2, 2, 1, 4, 1, 1],
"^": [4, 3, 1, 1, 1, 1],
"_": [1, 1, 1, 2, 2, 4],
"`": [1, 1, 1, 4, 2, 2],
"a": [1, 2, 1, 1, 2, 4],
"b": [1, 2, 1, 4, 2, 1],
"c": [1, 4, 1, 1, 2, 2],
"d": [1, 4, 1, 2, 2, 1],
"e": [1, 1, 2, 2, 1, 4],
"f": [1, 1, 2, 4, 1, 2],
"g": [1, 2, 2, 1, 1, 4],
"h": [1, 2, 2, 4, 1, 1],
"i": [1, 4, 2, 1, 1, 2],
"j": [1, 4, 2, 2, 1, 1],
"k": [2, 4, 1, 2, 1, 1],
"l": [2, 2, 1, 1, 1, 4],
"m": [4, 1, 3, 1, 1, 1],
"n": [2, 4, 1, 1, 1, 2],
"o": [1, 3, 4, 1, 1, 1],
"p": [1, 1, 1, 2, 4, 2],
"q": [1, 2, 1, 1, 4, 2],
"r": [1, 2, 1, 2, 4, 1],
"s": [1, 1, 4, 2, 1, 2],
"t": [1, 2, 4, 1, 1, 2],
"u": [1, 2, 4, 2, 1, 1],
"v": [4, 1, 1, 2, 1, 2],
"w": [4, 2, 1, 1, 1, 2],
"x": [4, 2, 1, 2, 1, 1],
"y": [2, 1, 2, 1, 4, 1],
"z": [2, 1, 4, 1, 2, 1],
"{": [4, 1, 2, 1, 2, 1],
"|": [1, 1, 1, 1, 4, 3],
"}": [1, 1, 1, 3, 4, 1],
"~": [1, 3, 1, 1, 4, 1],
}
CODE128_B_VALUES = {
char: i
for i, char in enumerate(
" !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
)
}
START_B = [2, 1, 1, 4, 1, 2]
START_B_VALUE = 104
STOP = [2, 3, 3, 1, 1, 1, 2]
# Checksum symbol patterns (indices 0–102 for modulo-103 calculation)
CHECKSUM_PATTERNS = [
[2, 1, 2, 2, 2, 2],
[2, 2, 2, 1, 2, 2],
[2, 2, 2, 2, 2, 1],
[1, 2, 1, 2, 2, 3],
[1, 2, 1, 3, 2, 2],
[1, 3, 1, 2, 2, 2],
[1, 2, 2, 2, 1, 3],
[1, 2, 2, 3, 1, 2],
[1, 3, 2, 2, 1, 2],
[2, 2, 1, 2, 1, 3],
[2, 2, 1, 3, 1, 2],
[2, 3, 1, 2, 1, 2],
[1, 1, 2, 2, 3, 2],
[1, 2, 2, 1, 3, 2],
[1, 2, 2, 2, 3, 1],
[1, 1, 3, 2, 2, 2],
[1, 2, 3, 1, 2, 2],
[1, 2, 3, 2, 2, 1],
[2, 2, 3, 2, 1, 1],
[2, 2, 1, 1, 3, 2],
[2, 2, 1, 2, 3, 1],
[2, 1, 3, 2, 1, 2],
[2, 2, 3, 1, 1, 2],
[3, 1, 2, 1, 3, 1],
[3, 1, 1, 2, 2, 2],
[3, 2, 1, 1, 2, 2],
[3, 2, 1, 2, 2, 1],
[3, 1, 2, 2, 1, 2],
[3, 2, 2, 1, 1, 2],
[3, 2, 2, 2, 1, 1],
[2, 1, 2, 1, 2, 3],
[2, 1, 2, 3, 2, 1],
[2, 3, 2, 1, 2, 1],
[1, 1, 1, 3, 2, 3],
[1, 3, 1, 1, 2, 3],
[1, 3, 1, 3, 2, 1],
[1, 1, 2, 3, 1, 3],
[1, 3, 2, 1, 1, 3],
[1, 3, 2, 3, 1, 1],
[2, 1, 1, 3, 1, 3],
[2, 3, 1, 1, 1, 3],
[2, 3, 1, 3, 1, 1],
[1, 1, 2, 1, 3, 3],
[1, 1, 2, 3, 3, 1],
[1, 3, 2, 1, 3, 1],
[1, 1, 3, 1, 2, 3],
[1, 1, 3, 3, 2, 1],
[1, 3, 3, 1, 2, 1],
[3, 1, 3, 1, 2, 1],
[2, 1, 1, 3, 3, 1],
[2, 3, 1, 1, 3, 1],
[2, 1, 3, 1, 1, 3],
[2, 1, 3, 3, 1, 1],
[2, 1, 3, 1, 3, 1],
[3, 1, 1, 1, 2, 3],
[3, 1, 1, 3, 2, 1],
[3, 3, 1, 1, 2, 1],
[3, 1, 2, 1, 1, 3],
[3, 1, 2, 3, 1, 1],
[3, 3, 2, 1, 1, 1],
[3, 1, 4, 1, 1, 1],
[2, 2, 1, 4, 1, 1],
[4, 3, 1, 1, 1, 1],
[1, 1, 1, 2, 2, 4],
[1, 1, 1, 4, 2, 2],
[1, 2, 1, 1, 2, 4],
[1, 2, 1, 4, 2, 1],
[1, 4, 1, 1, 2, 2],
[1, 4, 1, 2, 2, 1],
[1, 1, 2, 2, 1, 4],
[1, 1, 2, 4, 1, 2],
[1, 2, 2, 1, 1, 4],
[1, 2, 2, 4, 1, 1],
[1, 4, 2, 1, 1, 2],
[1, 4, 2, 2, 1, 1],
[2, 4, 1, 2, 1, 1],
[2, 2, 1, 1, 1, 4],
[4, 1, 3, 1, 1, 1],
[2, 4, 1, 1, 1, 2],
[1, 3, 4, 1, 1, 1],
[1, 1, 1, 2, 4, 2],
[1, 2, 1, 1, 4, 2],
[1, 2, 1, 2, 4, 1],
[1, 1, 4, 2, 1, 2],
[1, 2, 4, 1, 1, 2],
[1, 2, 4, 2, 1, 1],
[4, 1, 1, 2, 1, 2],
[4, 2, 1, 1, 1, 2],
[4, 2, 1, 2, 1, 1],
[2, 1, 2, 1, 4, 1],
[2, 1, 4, 1, 2, 1],
[4, 1, 2, 1, 2, 1],
[1, 1, 1, 1, 4, 3],
[1, 1, 1, 3, 4, 1],
[1, 3, 1, 1, 4, 1],
[1, 1, 4, 1, 1, 3],
[1, 1, 4, 3, 1, 1],
[4, 1, 1, 1, 1, 3],
[4, 1, 1, 3, 1, 1],
[1, 1, 3, 1, 4, 1],
[1, 1, 4, 1, 3, 1],
[3, 1, 1, 1, 4, 1],
[4, 1, 1, 1, 3, 1],
[2, 1, 1, 4, 1, 2],
[2, 1, 1, 2, 1, 4],
[2, 1, 1, 2, 3, 2],
]
# Data
content = "SHIP-2024-ABC123"
# Encode: start + data + checksum + stop
bars = list(START_B)
checksum = START_B_VALUE
for i, char in enumerate(content):
pattern = CODE128_B.get(char, CODE128_B[" "])
bars.extend(pattern)
checksum += CODE128_B_VALUES.get(char, 0) * (i + 1)
bars.extend(CHECKSUM_PATTERNS[checksum % 103])
bars.extend(STOP)
# Convert bar widths to binary (1=bar, 0=space)
binary_pattern = []
is_bar = True
for width in bars:
binary_pattern.extend([1 if is_bar else 0] * width)
is_bar = not is_bar
# Layout
barcode_height = 200
quiet_zone = 30
full_pattern = [0] * quiet_zone + binary_pattern + [0] * quiet_zone
barcode_width = len(full_pattern)
barcode_array = np.array([full_pattern] * barcode_height)
# Zone boundaries for structural annotations
# Code 128 standard: every symbol (except STOP) = 11 modules; STOP = 13 modules
_sw = 11
_stop_w = sum(STOP) # 13
_qz0_end = quiet_zone
_start_end = _qz0_end + _sw
_data_end = _start_end + len(content) * _sw
_check_end = _data_end + _sw
_stop_end = _check_end + _stop_w
zones = [
(_qz0_end - quiet_zone, _qz0_end, "Quiet Zone"),
(_qz0_end, _start_end, "Start"),
(_start_end, _data_end, f"Data · Code B ({len(content)} chars)"),
(_data_end, _check_end, "Check"),
(_check_end, _stop_end, "Stop"),
(_stop_end, barcode_width, "Quiet Zone"),
]
# Plot — landscape canvas: figsize=(8, 4.5) × dpi=400 → 3200×1800 px
fig, ax = plt.subplots(figsize=(8, 4.5), dpi=400, facecolor=PAGE_BG)
ax.set_facecolor(PAGE_BG)
# Theme-adaptive colormap: 0 (space) → PAGE_BG, 1 (bar) → INK
bar_cmap = LinearSegmentedColormap.from_list("barcode_cmap", [PAGE_BG, INK], N=2)
ax.imshow(barcode_array, cmap=bar_cmap, aspect="auto", interpolation="nearest", vmin=0, vmax=1)
ax.set_xticks([])
ax.set_yticks([])
# Structural zone annotations above the barcode
y_tick_top = 0 # tick mark at barcode top edge
y_bracket = -9 # horizontal bracket line
y_label = -20 # zone label center
for x0, x1, label in zones:
cx = (x0 + x1) / 2
ax.plot([x0, x1], [y_bracket, y_bracket], color=INK_MUTED, lw=0.6, solid_capstyle="butt")
ax.plot([x0, x0], [y_tick_top, y_bracket], color=INK_MUTED, lw=0.6)
ax.plot([x1, x1], [y_tick_top, y_bracket], color=INK_MUTED, lw=0.6)
ax.text(cx, y_label, label, fontsize=6, ha="center", va="center", color=INK_MUTED, fontfamily="monospace")
# Human-readable text below barcode
ax.text(
barcode_width / 2,
barcode_height + 28,
content,
fontsize=16,
ha="center",
va="top",
fontfamily="monospace",
fontweight="bold",
color=INK,
)
ax.set_xlim(-10, barcode_width + 10)
ax.set_ylim(barcode_height + 75, -38)
for spine in ax.spines.values():
spine.set_visible(False)
# Style
ax.set_title("barcode-code128 · python · matplotlib · anyplot.ai", fontsize=12, fontweight="medium", color=INK, pad=8)
ax.tick_params(colors=INK_SOFT)
fig.subplots_adjust(left=0.02, right=0.98, top=0.93, bottom=0.04)
# Save
plt.savefig(f"plot-{THEME}.png", dpi=400, facecolor=PAGE_BG)
Part of Code 128 Barcode on anyplot.ai.