Applications often use page headers and footers when printing to show things like page numbers, document title, etc.  It would be nice if GtkPrint made this a little easier.

When I helped port libgtkhtml from GnomePrint to GtkPrint, the printing API we were left with was kind of clunky and awkward because the library allows applications to draw a custom header and footer on each page, while the library itself draws the main content.  With WebKit/GTK+ strugging with the same issue in their printing API, it got me thinking about the problem again.

Here's a proposal for extending GtkPrintOperation to make fixed-height page headers and footers easier.  I think it should be backward-compatible.

Add the following functions to GtkPrintOperation:

    gdouble  gtk_print_operation_get_header_height (GtkPrintOperation *op,
                                                    GtkUnit unit);
    void     gtk_print_operation_set_header_height (GtkPrintOperation *op,
                                                    gdouble height,
                                                    GtkUnit unit);
    gdouble  gtk_print_operation_get_footer_height (GtkPrintOperation *op,
                                                    GtkUnit unit);
    void     gtk_print_operation_set_footer_height (GtkPrintOperation *op,
                                                    gdouble height,
                                                    GtkUnit unit);

The header and footer heights would default to 0.0.

Then add "draw-header" and "draw-footer" signals to GtkPrintOperation.  These have the same signature as the "draw-page" signal, but each get their own appropriately sized GtkPrintContext.  gtk_print_context_get_height() would return the header or footer height instead of the main drawing area height.

The new signals would only be emitted if the corresponding header/footer heights are greater than zero, and the height of the main drawing area would be decreased to accommodate them.

The signals would be emitted top-to-bottom:

    "draw-header"  (only if header-height > 0)
    "draw-page"
    "draw-footer"  (only if footer-height > 0)

Then the three contexts would be assembled and the page printed.

I'm not very familiar with the internals of GtkPrint yet, so I haven't attempted an implementation.  But does this proposal sound feasible?