Using native unix print system

[Martin Fischer <martinfischer8 t-online de>]

Hi,

I'm trying to use the Unix native print system of GTK+ 2 at the moment. 
I'm not able to create any output neither to the printer nor to file.
In order to track down the problem a bit more, I created a small test 
application:

----
#include <gtk/gtk.h>
#include <gtk-unix-print-2.0/gtk/gtkunixprint.h>

static void
print_end(GtkPrintJob *print_job, gpointer user_data, const GError *err)
{
        if (err == NULL)
                return;
        g_assert(err == NULL);
}

static void
print_page(GtkWidget *widget, gpointer user_data)
{
        GtkWindow *parent = user_data;
        GtkPrintJob *print_job;
        GtkPrinter *printer;
        GtkPrintSettings *settings;
        GtkPageSetup *page_setup;
        GtkWidget *dialog;
        GError *err = NULL;
        cairo_t *cr;
        cairo_surface_t *surface;
        char * status;

        dialog = gtk_print_unix_dialog_new(NULL, parent);
        if (gtk_dialog_run(GTK_DIALOG(dialog)) == GTK_RESPONSE_OK) {

		printer = gtk_print_unix_dialog_get_selected_printer( 
GTK_PRINT_UNIX_DIALOG(dialog));
		settings = gtk_print_unix_dialog_get_settings( 
GTK_PRINT_UNIX_DIALOG(dialog));
		page_setup = gtk_print_unix_dialog_get_page_setup( 
GTK_PRINT_UNIX_DIALOG(dialog));
        
		print_job = gtk_print_job_new("Example title", printer, settings, 
page_setup);
                surface = gtk_print_job_get_surface( print_job, NULL  );
                cr = cairo_create( surface );
                status = cairo_status_to_string( cairo_status( cr ));
                
                cairo_set_source_rgb(cr, 0.6, 0.6, 0.6);
                cairo_set_line_width(cr, 1);
        
                cairo_rectangle(cr, 20, 20, 120, 80);
                cairo_rectangle(cr, 180, 20, 80, 80);
                cairo_stroke_preserve(cr);
                cairo_fill(cr);
        
                cairo_show_page( cr );
                status = cairo_status_to_string( cairo_status( cr ));
                
                gtk_print_job_send(print_job, print_end, NULL, NULL);
                
                //g_object_unref(print_job);
                //g_object_unref(page_setup);
                //g_object_unref(settings);
                //g_object_unref(printer);
        }
        gtk_widget_destroy(dialog);
        return;

}

int
main(int argc, char **argv)
{
        GtkWidget *window;
        GtkWidget *button;

        gtk_init(&argc, &argv);
        window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
        g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
        gtk_container_set_border_width(GTK_CONTAINER(window), 10);

        button = gtk_button_new_with_label("Print");
        gtk_container_add(GTK_CONTAINER(window), button);
	g_signal_connect(button, "clicked", G_CALLBACK(print_page), 
GTK_WINDOW(window));
        gtk_widget_show_all(window);
        gtk_main();
        return 0;
}
----
This is the Makefile
----
EXES = unixprint
CC = cc
CFLAGS = -Wall -g -I /usr/include/gtk-unix-print-2.0 `pkg-config 
--cflags --libs gtk+-2.0` `pkg-config --cflags --libs gtk+-unix-print-2.0`

all:
        $(MAKE) $(EXES)

%: %.c
        $(CC) $(CFLAGS) $  c -o $@

clean:
        rm -f $(EXES) *.o
----

Everything seems to work, I don't get any error messages and print_end 
is called. When printing to file the files are created with a zero byte 
length, whether I select PDF or PS.

So I'm pretty much clueless. It looks like I'm missing something basic 
but what? Searching the Internet didn't help.

So any hints or ideas?

Regards
Martin