A new CBSubs build release is now available with this trigger implemented. Usage example as follows in CB Auto Actions.
Global
Triggers: onCPayAfterDrawInvoice
Type: Code
User: Automatic
Access: Everybody
Action
Method: HTML
Code:
Output
Display: Silent
Layout:
Code:
$variables['var2'] = $content;
Method: PHP
Parameters
References: Variable 2
You'll now notice when viewing an invoice it will just say "Hello!". You can use this functionality to completely replace the invoice rendering with your own behavior as needed. You can access the invoice object using var4 which gives you access to the cbpaidPaymentBasket object and all its data in the _cbsubs_payment_baskets database table (e.g. [var4_mc_gross] or can be accessed from PHP rendering with $variables).
If you need further explanation of variables and what information they hold for your usage don't hesitate to ask. This should let you completely replace invoice display with whatever requirements you may have. You will need to implement your own QR Code generating behavior.