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: ggplot2 3.5.1 | R 4.4.1
#' Quality: 86/100 | Created: 2026-05-21
library(ggplot2)
library(ragg)
# --- Theme tokens -----------------------------------------------------------
THEME <- Sys.getenv("ANYPLOT_THEME", "light")
PAGE_BG <- if (THEME == "light") "#FAF8F1" else "#1A1A17"
INK <- if (THEME == "light") "#1A1A17" else "#F0EFE8"
INK_SOFT <- if (THEME == "light") "#4A4A44" else "#B8B7B0"
INK_MUTED <- if (THEME == "light") "#6B6A63" else "#A8A79F"
# --- Code 128 Subset B patterns (values 0-106 in order, stop appended) -----
# Each string: 6 digit widths (bar-space-bar-space-bar-space), 11 modules each
# Stop pattern: 7 digit widths, 13 modules
CODE128 <- c(
"212222","222122","222221","121223","121322","131222","122213","122312",
"132212","221213","221312","231212","112232","122132","122231","113222",
"123122","123221","223211","221132","221231","213212","223112","312131",
"311222","321122","321221","312212","322112","322211","212123","212321",
"232121","111323","131123","131321","112313","132113","132311","211313",
"231113","231311","112133","112331","132131","113123","113321","133121",
"313121","211331","231131","213113","213311","213131","311123","311321",
"331121","312113","312311","332111","314111","221411","431111","111224",
"111422","121124","121421","141122","141221","112214","112412","122114",
"122411","142112","142211","241211","221114","413111","241112","134111",
"111242","121142","121241","114212","124112","124211","411212","421112",
"421211","212141","214121","412121","111143","111341","131141","114113",
"114311","411113","411311","113141","114131","311141","411131","211412",
"211214","211232",
"2331112" # stop symbol (index 108 in R / code value 106+stop)
)
# --- Encode a string using Code 128 Subset B --------------------------------
# Returns vector of pattern strings (data + check + stop)
encode_code128b <- function(text) {
chars <- strsplit(text, "")[[1]]
code_vals <- vapply(chars, function(ch) utf8ToInt(ch) - 32L, integer(1L))
start_val <- 104L # Start B
check_val <- (start_val + sum(seq_along(code_vals) * code_vals)) %% 103L
all_vals <- c(start_val, code_vals, check_val)
c(CODE128[all_vals + 1L], CODE128[107L]) # patterns + stop (stop is at index 107)
}
# --- Build rectangle data frame from encoded patterns -----------------------
patterns_to_df <- function(patterns, quiet_modules = 10L) {
x <- quiet_modules
rows <- list()
for (pat in patterns) {
widths <- as.integer(strsplit(pat, "")[[1]])
for (i in seq_along(widths)) {
if (i %% 2L == 1L) { # odd index = bar (black)
rows[[length(rows) + 1L]] <- c(x, x + widths[i])
}
x <- x + widths[i]
}
}
total_w <- x + quiet_modules
mat <- do.call(rbind, rows)
df <- data.frame(xmin = mat[, 1], xmax = mat[, 2], ymin = 0, ymax = 1)
list(df = df, total_w = total_w)
}
# --- Data -------------------------------------------------------------------
set.seed(42)
label_text <- "SPEC-LAB-2024-X789"
patterns <- encode_code128b(label_text)
barcode <- patterns_to_df(patterns)
bar_df <- barcode$df
total_w <- barcode$total_w
# White barcode background (always white for scan reliability)
bg_rect <- data.frame(xmin = 0, xmax = total_w, ymin = 0, ymax = 1)
x_pad <- total_w * 0.05
# --- Plot -------------------------------------------------------------------
p <- ggplot() +
geom_rect(
data = bg_rect,
aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax),
fill = "white", color = NA
) +
geom_rect(
data = bar_df,
aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax),
fill = "black", color = NA
) +
# Subtle frame around barcode to anchor it visually
geom_rect(
data = bg_rect,
aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax),
fill = NA, color = INK_SOFT, linewidth = 0.5
) +
annotate(
"text",
x = total_w / 2, y = -0.26,
label = label_text,
size = 6.5,
family = "mono",
color = INK,
fontface = "plain"
) +
annotate(
"text",
x = total_w / 2, y = 1.30,
label = "Specimen Label — Healthcare Lab Tracking",
size = 4.5,
color = INK_SOFT,
fontface = "italic"
) +
labs(
title = "barcode-code128 · r · ggplot2 · anyplot.ai",
caption = "Code 128 Subset B · Mod-103 check digit · Quiet zones: 10× module width"
) +
coord_cartesian(
xlim = c(-x_pad, total_w + x_pad),
ylim = c(-0.55, 1.50),
expand = FALSE,
clip = "off"
) +
theme_void() +
theme(
plot.background = element_rect(fill = PAGE_BG, color = PAGE_BG),
panel.background = element_rect(fill = PAGE_BG, color = NA),
plot.title = element_text(
color = INK,
size = 12,
hjust = 0.5,
face = "bold",
margin = margin(b = 10, t = 8)
),
plot.caption = element_text(
color = INK_MUTED,
size = 7,
hjust = 0.5,
margin = margin(t = 6, b = 4)
),
plot.margin = margin(30, 80, 20, 80)
)
# --- Save -------------------------------------------------------------------
ggsave(
filename = sprintf("plot-%s.png", THEME),
plot = p,
device = ragg::agg_png,
width = 8,
height = 4.5,
units = "in",
dpi = 400
)
Part of Code 128 Barcode on anyplot.ai.