This was actually the (first) reason we added the tax classes: to show
them in columns on the invoice—without the class we would need a column
for each tax rate, even though they are the same tax.
The invoice design has the product total with taxes at the last column,
above the tax base, that i am not so sure about, but it seems that it
has not brought any problem whatsoever so far, so it remains as is.
Had to reduce the invoice’s font size to give more space to the table
or the columns would be right next to each other. Oriol also told me
to add more vertical spacing to the table’s footer.
Although it is possible to just print the invoice from the browser, many
people will not even try an assume that they can not create a PDF for
the invoice.
I thought of using Groff or TeX to create the PDF, but it would mean
maintaining two templates in two different systems (HTML and whatever i
would use), and would probably look very different, because i do not
know Groff or TeX that well.
I wish there was a way to tell the browser to print to PDF, and it can
be done, but only with the Chrome Protocol to a server-side running
Chrome instance. This works, but i would need a Chrome running as a
daemon.
I also wrote a Qt application that uses QWebEngine to print the PDF,
much like wkhtmltopdf, but with support for more recent HTML and CSS
standards. Unfortunately, Qt 6.4’s embedded Chromium does not follow
break-page-inside as well as WeasyPrint does.
To use WeasyPrint, at first i wanted to reach the same URL as the user,
passing the cookie to WeasyPrint so that i can access the same invoice
as the user, something that can be done with wkhtmltopdf, but WeasyPrint
does not have such option. I did it with a custom Python script, but
then i need to package and install that script, that is not that much
work, but using the Debian-provided script is even less work, and less
likely to drift when WeasyPrint changes API.
Also, it is unnecessary to do a network round-trip from Go to Python
back to Go, because i can already write the invoice HTML as is to
WeasyPrint’s stdin.
I am planning to use WeasyPrint to “generate PDF” from the same HTML
that the user view, but it seems that it does not support flex’s gap
and some other properties that i had to change to work in both user
agents.
I also moved the invoice’s “footer” inside the last product’s body
because i do not want the footer to be a “widow”.
Had to group name and description rows in tbody because i do not want
to break them on pagination.
I also could not use tfoot for subtotal, taxes, and total because then
they appear on every page.
The disclaimer should appear only at the very bottom of the last page,
but i do not know how to do that; using position fixed shows it on
every page.
jordi fita mas