GS1-128/Code 128 barcode encoder

This is a simple GS1-128 barcode encoder library. The reason to choose it over others is simply that it is written in pure C code and has no external dependencies. That's right - it doesn't even depend on a graphics library. As a bonus, the barcodes produced by this program will automatically use the Code 128 A, B, or C modes based on what generates the shortest barcode.

Here's how to use:

    const char *str = "[FNC1] 00 12345678 0000000001";
    size_t barcode_length = code128_estimate_len(str);
    char *barcode_data = (char *) malloc(barcode_length);
    int i;

    barcode_length = code128_encode_gs1(str, barcode_data, barcode_length);

    /* barcode_length is now the actual number of "bars". */
    for (i = 0; i < barcode_length; i++) {
        if (barcode_data[i])
            draw_vertical_bar_at_column(i);
    }

Once you get barcode_data, each byte corresponds to whether a vertical line should be drawn. If the byte is 0xff, then draw a line. If the byte is 0x00, then don't.

Compiling and testing

The main library, code128.[ch], doesn't have any dependencies. The test program depends on libpng, so make sure to install that first. On Debian/Ubuntu, run:

sudo apt install libpng-dev

On Windows, with MSYS2, run:

pacman -S --needed base-devel mingw-w64-x86_64-toolchain
pacman -S mingw-w64-x86_64-libpng

Details on how to install and setup MSYS2 environment on Windows can be found here and here .

Then run make. The result is a test program that creates png files of barcode data passed on the commandline.

On Windows, to build the libraries and the test program for different architectures, you should open Powershell and run:

mingw-32-make.exe all

The regression tests require zbar. Install zbar on Debian/Ubuntu by:

sudo apt install zbar-tools

Or on OSX:

brew install zbar

Then run make check.

Integrating

If you're using C or C++, the easiest way of integrating this code into your program is to just copy code128.[ch] to your tree. If you're not using C, then calling code128png from your app may be an option as well.