[gedit/wip/printing-enhancements] print-preview: begin support of selected pages to print

[Sébastien Wilmet <swilmet src gnome org>]

commit 1750f7232ca87c32b560ec310427fc1cc47abd36
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sun Jun 28 18:51:20 2015 +0200

    print-preview: begin support of selected pages to print

 gedit/gedit-print-preview.c |   32 +++++++++++++++++++++++++++++++-
 1 files changed, 31 insertions(+), 1 deletions(-)
---
diff --git a/gedit/gedit-print-preview.c b/gedit/gedit-print-preview.c
index a74dddd..444eea6 100644
--- a/gedit/gedit-print-preview.c
+++ b/gedit/gedit-print-preview.c
@@ -355,6 +355,26 @@ prev_button_clicked (GtkWidget         *button,
        gdk_event_free (event);
 }
 
+/* Skip unselected pages. */
+static gboolean
+adjust_nth_page_forward (GeditPrintPreview *preview,
+                        gint              *page)
+{
+       gint n_pages = get_n_pages (preview);
+       gint new_page;
+
+       for (new_page = *page; new_page < n_pages; new_page++)
+       {
+               if (gtk_print_operation_preview_is_selected (preview->gtk_preview, new_page))
+               {
+                       *page = new_page;
+                       return TRUE;
+               }
+       }
+
+       return FALSE;
+}
+
 static void
 next_button_clicked (GtkWidget         *button,
                     GeditPrintPreview *preview)
@@ -371,7 +391,17 @@ next_button_clicked (GtkWidget         *button,
        }
        else
        {
-               page = preview->cur_page + preview->n_columns;
+               gint i;
+
+               page = preview->cur_page;
+               for (i = 0; i < preview->n_columns; i++)
+               {
+                       page++;
+                       if (!adjust_nth_page_forward (preview, &page))
+                       {
+                               break;
+                       }
+               }
        }
 
        goto_page (preview, MIN (page, n_pages - 1));