Re: Printing with GTK/Cairo produces only empty pages

[Chris Vine <chris cvine freeserve co uk>]

On Mon, 14 Oct 2013 19:34:53 +0200
Satz Klauer <satzklauer googlemail com> wrote:

> Hi,
>
> I try to print some vector data using GTK/Cairo. Unfortunately my
> printer only produces empty pages, means there is no print operation,
> the paper sheets are just moved.
>
> That's how I'm initialising everything:
>
> GtkPrintOperation *op;
>
> op = gtk_print_operation_new();
> gtk_print_operation_set_allow_async(op,TRUE);
> gtk_print_operation_set_n_pages(op, 1);
> gtk_print_operation_set_unit (op,GTK_UNIT_POINTS);
> g_signal_connect (op, "draw_page", G_CALLBACK(draw_page), NULL);
> gtk_print_operation_run (op, GTK_PRINT_OPERATION_ACTION_PRINT,NULL,
> NULL);
>
> The print-callback (which is called successfuly) looks like this:
>
> static void draw_page (GtkPrintOperation *operation,GtkPrintContext
> *context,int page_nr)
> {
>    GtkPrintSettings *settings;
>
>    cairo_t *cr = gtk_print_context_get_cairo_context (context);
>    settings = gtk_print_operation_get_print_settings (operation);
>    cairo_set_source_rgb(dc,0,0,0);
>    cairo_set_line_width(dc,m_data->config.m_linewidth);
>
>    cairo_move_to (cr,x0,y0);
>    cairo_line_to (cr,x1,y1);
>    cairo_line_to (cr,x2,y2);
>    ...
>    // some more lines...
> }
>
> What could be missing here? Do I have to close/finish the drawing
> operation somehow?

That depends on what you are trying to draw.  I suspect you are looking
for cairo_stroke(), but you could also consider cairo_fill(). Note also
the *_preserve() variants.

Chris