gtk print for printing an image

[Nicolas Soubeiran <nicolas soubeiran gmail com>]

Hi all,
I try to use GtkPrintOperation for printing an image and there is
something I do not understand.
When I am in the draw-page callback, I get the cairo context from
GtkPrintContext which is at 72dpi and the "draw rectangle" is smaller
than 1000x1000 (for A4 sheet) and my image pixbuf is 2000x3200. So I
need to rescale it (and loose resolution) to have a "full image"
print.

I have understood that I should not change the resolution of the given
print context when printing so I do not know how I can avoid
rescaling.

sample code :
static void s_draw_page(GtkPrintOperation *operation,GtkPrintContext
*context, gint page_nr, GdkPixbuf* image)
{
  GdkPixbuf* render;
  GtkPrintSettings * settings;
  cairo_t *cr;
  gdouble width, height;
  gint image_width, image_height;

  settings = gtk_print_operation_get_print_settings(operation);
  width = gtk_print_context_get_width (context);
  height = gtk_print_context_get_height(context);
  image_width = gdk_pixbuf_get_width(image);
  image_height = gdk_pixbuf_get_height(image);
  g_message("GtkPrintContext  dpi : %f, setting dpi %d",
        gtk_print_context_get_dpi_x(context),
        gtk_print_settings_get_resolution(settings));
  if(image_width >  width || image_height > height )
  {
    g_warning("image is larger than printing zone : rescale");
    render = gdk_pixbuf_scale_simple(image, (int) width , (int)height );
  }
  else
  {
    render = GDK_PIXBUF(g_object_ref( image));
  }
  cairo_rectangle (cr, 0, 0, width, height);
  gdk_cairo_set_source_pixbuf(cr, render );
  cairo_fill(cr),
  g_object_unref(render);
}

output look likes:
message ** GtkPrintContext  dpi : 72.000000, setting dpi 600
warning ** image is larger than printing zone : rescale