Re: GtkPrintOperation; request for assistance

[Emmanuele Bassi <ebassi gmail com>]

Hi;

On 7 February 2017 at 00:09, Norbert de Jonge <mail norbertdejonge nl> wrote:

> Yesterday, I finished the migration of a 16+ year old GTK+ 1.2
> application to GTK+ 3.18.

Congrats!

> In previous releases of the application, printing was done by writing
> directly to "lpr". I want code to be C99 compatible, so I replaced the
> popen() functions with GtkPrintOperation.
>
> Currently, printing works properly, but both the preview and output end
> after page 1. This is, of course, not the intended behavior.
>
> A quick glance at the print.c source file shows the problem. The
> relevant code is under "/*** print operation ***/" and in the PrintPage
> function.
>
> The solution... I don't know.

The solution would be to use Cairo to render on a PDF surface, instead
of generating a massive string and then sending it to lpr, because
this is not 1997 any more, and we do have better API for printing
data, these days. :-)

The GNOME Dictionary is a simple application that has the ability to
print a text buffer. Here's the relevant, self-contained code:

https://git.gnome.org/browse/gnome-dictionary/tree/src/gdict-print.c

You construct a buffer of lines (possibly using things like GString,
instead of sprintf()) and then use Pango to create a layout; then,
Cairo to draw the layout at the given page size and position. This has
the advantage of giving you PDF output and preview working out of the
box.

Ciao,
 Emmanuele.

-- 
https://www.bassi.io
[@] ebassi [@gmail.com]