Printing a barcode or QR Code on a PDF

The WaterWoo PDF Premium and EDDiMark PDF plugins can add barcodes and QR codes to PDFs dynamically upon download request via WooCommerce or Easy Digital Downloads. This is because both WordPress plugins use TCPDF to write PDF content, and TCPDF allows for barcode creation. Though this blog post might also be helpful for someone just trying to figure out how to write a barcode with TCPDF and PHP, these instructions are more geared toward a WordPress developer wishing to add 1D or 2D barcodes to existing PDF files.

For WaterWoo, use the ‘wwpdf_add_barcode’ filter hook in the plugin (located in classes/wwpdf-watermark.php). For EDDiMark, use the ‘eddimark_add_barcode’ filter hook (located in classes/eddimark-watermark.php). For TCPDF Bridge, use the ‘wptcpdfb_add_barcode’ filter hook (located in classes/wptcpdfb-watermark.php).

Your hooked function should simply create and return an array of arguments to pass to the open source TCPDF barcoding methods (1D or 2D). The array has ten arguments, the first of which decides whether you want a 1D or 2D QR code. The rest of the arguments are specific to either TCPDF write1DBarcode() or TCPDF write2DBarcode(), which take slightly different arguments.

What’s the difference between a 1D and a 2D barcode?

On the left, a 1D barcode. Data is read horizontally via bars of differing width. On the right, a 2D barcode; data is read horizontally and vertically. You may be familiar with the 2D barcode, as QR codes have become a popular means of distributing branding and marketing via smartphones and other readers.

Write a 1D Barcode with TCPDF

1D barcode types available when using TCPDF are: ‘C39’, ‘C39+’, ‘C39E’, ‘C39E+’, ‘C93’, ‘S25’, ‘S25+’, ‘I25’, ‘I25+’, ‘C128’, ‘C128A’, ‘C128B’, ‘C128C’, ‘EAN2’, ‘EAN5’, ‘EAN8’, ‘EAN13’, ‘UPCA’, ‘UPCE’, ‘MSI’, ‘MSI+’, ‘POSTNET’, ‘PLANET’, ‘RMS4CC’, ‘KIX’, ‘IMB’, ‘IMBPRE’, ‘CODABAR’, ‘CODE11’, ‘PHARMA’, and ‘PHARMA2T’.

write1DBarcode( $code, $type, $x='', $y='', $w='', $h='', $xres='', $style=array(), $align='' )

You don’t need to pass ALL the arguments, but you can if you need to. Remember, the first argument for your hooked function return array is just ‘1D’ or ‘2D’, then the remaining 5+ arguments should follow. A sample PHP hooked function might look like this:

function my_1D_barcode_function( $barcode_array, $identifier ) {

    // $identifier may be Order ID, which could be used to get customer/order data to include in barcode (see example below)
    return array '1D', '9780671872298', 'UPCA', '100', '200', '100', '30'  );

}
add_filter( 'wwpdf_add_barcode', 'my_1D_barcode_function', 10, 2 );

That will add a 10x3cm UPC barcode 10cm across and 20cm down the page, which says “My barcode alphanumeric content.” Of course edit it to make sure the arguments create the barcode you want, where you want it. You could add this code to your (child) theme functions.php file, or by using the Code Snippets plugin if you’re unfamiliar with how to edit theme files.

Note: The code in this post applies to WaterWoo version 3.0+ and EDDiMark version 2.2+. It will be similar for older/other Little Package plugins. Sample code is not guaranteed to work.

Here’s where it gets fun for WooCommerce users (if it’s not fun and you have no idea what any of this means, please consider hiring a developer)! Since the WooCommerce order ID is included as an argument in the ‘wwpdf_add_barcode’ filter hook, you are able to add email, address, full name, etc., to the barcode (assuming you collected those details from your customer during WooCommerce checkout). You might try something like:

function phone_1D_barcode_function( $barcode_array, $order_id ) {

    $order = wc_get_order( $order_id );
    $order_data = $order->get_data();
    $phone = $order_data['billing']['phone'];

    if ( empty( $phone ) ) { 
	// no phone number yet, try seeing if user is logged in and has a saved phone number:
        if ( is_user_logged_in() ) {
            $user = wp_get_current_user();
            $phone = get_user_meta( $user->ID, 'billing_phone', true ) == '' ? '' : get_user_meta( $user->ID, 'billing_phone', true );
        }
    }

    if ( ! isset( $phone ) || $phone == '' ) { 
        $code = 'no phone';
    } else {
        // you might want to manipulate the phone number to remove +-_( first, like this:
        // $phone = preg_replace( '/D+/', '', $phone ); // uncomment to clean up and only use the digits
        $code = $phone;
    }
    return array( '1D', $code, 'C39E', '100', '200', '100', '30'  );

}
add_filter( 'wwpdf_add_barcode', 'phone_1D_barcode_function', 10, 2 );

This would create an C39 (extended) barcode, which accepts letters and numbers, as well as special characters. One thing to be mindful of is whether your chosen barcode accepts alphanumeric, or only numeric, as this is a common source of output error when generating barcodes dynamically. Were you to use ‘C39’ in the code above, it would have to be corrected to use uppercase letters ‘NO PHONE’ because C39 does not support lowercase.

Write a 2D Barcode with TCPDF

Create a 2D barcode with TCPDF very much how you create a 1D barcode, but by passing some slightly different parameters. For one, the $type of barcodes will obviously be different, because now we are 2D.

2D barcode types available in TCPDF are: ‘DATAMATRIX’, ‘PDF417(a,e,t,s,f,o0,o1,o2,o3,o4,o5,o6)’, ‘QRCODE’, ‘QRCODE,L’, ‘QRCODE,M’, ‘QRCODE,Q’, ‘QRCODE,H’, ‘RAW’, ‘RAW2’, and ‘TEST’.

write2DBarcode($code, $type, $x='', $y='', $w='', $h='', $style=array(), $align='', $distort=false)

You don’t need to pass ALL the arguments, but you can if you need to. Remember, the first argument for your hooked function return array is just ‘1D’ or ‘2D’, then the remaining 5+ arguments should follow. A sample PHP hooked function might look like this:

function my_2D_barcode_function( $barcode_array, $identifier ) {

    // $identifier may be Order ID, which could be used to get customer/order data to include in barcode (see example above)
    return array( '2D', 'My 2d barcode says HI', 'QRCODE', '100', '200', '100', '30'  );

}
add_filter( 'wwpdf_add_barcode', 'my_2D_barcode_function', 10, 2 );

Caveat

The ‘wwpdf_add_barcode’, ‘eddimark_add_barcode’, and ‘wptcpdfb_add_barcode’ filters were placed as a convenience for WordPress users who want to extend watermarking with barcodes. You’ll see it is not “plug and play” on the plugin backend; there are no “settings panels” where you can create barcodes. But it’s not much work for someone who is familiar with PHP/Wordpress, either. Hopefully you can understand this was not a “feature” built into WaterWoo, EDDiMark, or TCPDF Bridge because TCPDF may offer unpredictable results and we do not support TCPDF — it is 3rd party code. So please experiment with it, have fun, and if you have comments or suggestions, contact us.