//CHANGE THE LINE BELOW TO ADD OR REMOVE POST TYPES
//ADDITIONAL ATTRIBUTES OF THE SHORTCODE
//- [qr_code] will display the QR code for the current post type with a size of 100x100 pixels. Add this s a shortcode element on the front end with a 
// condition that the author can see it if you want to allow your customers to use this QR code in marketing or print.
//- [qr_code size="200x200"] will display a larger QR code for the current post type with a size of 200x200 pixels.
// LISTING QR CODE GENERATOR
// =============================================================================
function dw_add_custom_box() {
$post_types = array('website', 'snippet'); // CHANGE THE POST TYPES HERE
foreach ($post_types as $post_type) {
add_meta_box(
'dw_box_id', // Unique ID
'QR Code', // Box title
'dw_custom_box_html', // Content function
$post_type // Post type
);
}
}
add_action('add_meta_boxes', 'dw_add_custom_box');
function dw_custom_box_html($post) {
$post_name = get_the_title($post->ID); // Get the post name
?>
<h2>Save the post first, then grab the QR code. If you change the title of the post, the QR code might change, so double-check.</h2>
<img src="https://api.qrserver.com/v1/create-qr-code/?size=100x100&data=<?php echo esc_url(get_permalink($post->ID)); ?>" title="<?php echo esc_attr($post_name); ?>" />
<?php
// Add a download button that opens in a new tab
$download_url = "https://api.qrserver.com/v1/create-qr-code/?size=300x300&data=" . esc_url(get_permalink($post->ID));
$download_filename = sanitize_title_with_dashes($post_name) . "_qr_code.png"; // Sanitize the filename
?>
<br /><a href="<?php echo $download_url; ?>" download="<?php echo $download_filename; ?>" target="_blank">Download QR Code</a>
<?php
}
// Shortcode to display QR code on the front end
function dw_qr_code_shortcode($atts) {
$attributes = shortcode_atts(array(
'size' => '100x100',
'post_id' => get_the_ID(),
), $atts);
$qr_code_url = "https://api.qrserver.com/v1/create-qr-code/?size={$attributes['size']}&data=" . esc_url(get_permalink($attributes['post_id']));
return '<img src="' . $qr_code_url . '" />';
}
add_shortcode('qr_code', 'dw_qr_code_shortcode');
 

[qr_code]