Failed barcodes using CODE 128 with letters.

[jxr-koda]

I'm having a bit of trouble generating Code 128 B barcodes and I'm fairly lost as to why. I've written a short script that demonstrates the problem.

require 'vendor/autoload.php';

$code = '1GVRM3I09Z56';

//OLD Method
$generator = new \Picqer\Barcode\BarcodeGeneratorPNG();
$barcode = $generator->getBarcode($code, $generator::TYPE_CODE_128);
file_put_contents('goodbarcode.png', $barcode);

//NEW Method
$barcode = (new \Picqer\Barcode\Types\TypeCode128())->getBarcode($code);
$barcodeRenderer = new \Picqer\Barcode\Renderers\PngRenderer();
file_put_contents('failedbarcode.png', $barcodeRenderer->render($barcode));

The old method generates a working barcode that scans correctly. Here's the file it generated:

And the newer method, assuming I'm doing it correct, generates a barcode that can't be scanned:

Any idea what's going on?

Note: when I only use numbers in $code, there are no issues. I tried forcing TypeCode128B() but this did not resolve the issue.

[amiyoghoshstar]

Hey, just wanted to share what I found while troubleshooting this.

The difference comes from how the old and new APIs handle Code 128 generation internally.

The old call:

$generator = new \Picqer\Barcode\BarcodeGeneratorPNG();
$barcode = $generator->getBarcode($code, $generator::TYPE_CODE_128);

uses the legacy “auto” mode for Code 128. That one automatically picks the right subset (A/B/C), adds the start/stop symbols, checksum, and handles mixed content — so the result always scans fine.

The new call:

$barcode = (new \Picqer\Barcode\Types\TypeCode128())->getBarcode($code);
$barcodeRenderer = new \Picqer\Barcode\Renderers\PngRenderer();

is a lower-level API. It doesn’t automatically handle subset selection or include start/stop codes unless you use one of the specific subclasses (TypeCode128A, TypeCode128B, or TypeCode128C).

So in this example, using TypeCode128B fixes the issue:

$type = new \Picqer\Barcode\Types\TypeCode128B();
$barcode = $type->getBarcode('1GVRM3I09Z56');
$renderer = new \Picqer\Barcode\Renderers\PngRenderer();
file_put_contents('fixedbarcode.png', $renderer->render($barcode));

This one scans correctly again.

Basically, TypeCode128() is the base implementation, while TypeCode128B() (or A/C) includes the proper start/stop and subset logic. The old BarcodeGeneratorPNG just did all that automatically behind the scenes.