QR code generator

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About The Project

This is a simple QR code generator written in C. It reads a string from arguments and outputs an image or text.

Features

• Mode detection (numeric, alphanumeric, binary, kanji)
• Auto version selection
• Custom fg/bg color
• Boost EC level automatically to fit version
• Supported output formats:
  • Image: PNG, BMP, Targa, HDR, JPEG, farbfeld
  • Text (using Unicode block characters)
  • HTML

Future plans

• Micro QR code (μQR)
• More encoding modes
• Multi-encoded QR codes

Dependencies

• iconv (glibc)

CLI Usage

See qr --help for more information.

Library Usage

Example program:

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <qr/qr.h>

#define eprintf(...) fprintf(stderr, __VA_ARGS__)

int main() {
	struct qr_alloc alloc = QR_ALLOC(malloc, realloc, free);

	struct qr qr;
	memset(&qr, 0, sizeof(qr));

	const char *error = NULL;

	if (!qr_encode_utf8(&qr, alloc, "Hello world!", QR_MODE_AUTO, QR_VERSION_AUTO, QR_ECL_MEDIUM, &error)) {
		eprintf("Failed to encode data for QR code: %s\n", error);
		return 1;
	}

	if (!qr_prepare_data(&qr, &error)) {
		eprintf("Failed to prepare QR code data: %s\n", error);
		return 1;
	}

	if (!qr_render(&qr, &error, QR_MASK_AUTO)) {
		eprintf("Failed to render QR code: %s\n", error);
		return 1;
	}

	struct qr_pos pos;
	for (pos.y = 0; pos.y < qr.output.size; pos.y++) {
		for (pos.x = 0; pos.x < qr.output.size; pos.x++) {
			printf("%s", qr_bitmap_read(qr.output, pos) ? "##" : "  ");
		}
		printf("\n");
	}

	qr_close(&qr);

	return 0;
}

After running meson install, compile with

gcc main.c -o main -Wl,-rpath,/usr/local/lib -lQR -I/usr/local/include

Installing

Debian-based

sudo apt install build-essential meson

Then follow the instructions below

Other distros

Find dependencies listed above in your package manager or elsewhere:

git clone https://github.com/mekb-turtle/qr.git
cd qr
git checkout "$(git describe --tags --abbrev=0)" # checkout to latest tag, omit for latest commit
meson setup build
meson test -C build
meson install -C build