[evince] previewer: Enable/disable page navigation based on current page

[Carlos Garcia Campos <carlosgc src gnome org>]

commit a671eb08a98dd8e4637567949af281ce4b7c5496
Author: Robert Roth <robert roth off gmail com>
Date:   Sun Mar 15 20:39:25 2015 +0200

    previewer: Enable/disable page navigation based on current page
    
    https://bugzilla.gnome.org/show_bug.cgi?id=745840

 previewer/ev-previewer-window.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/previewer/ev-previewer-window.c b/previewer/ev-previewer-window.c
index dd34f25..ff2c42c 100644
--- a/previewer/ev-previewer-window.c
+++ b/previewer/ev-previewer-window.c
@@ -334,6 +334,22 @@ view_focus_changed (GtkWidget         *widget,
 }
 
 static void
+model_page_changed (EvDocumentModel* model,
+                   gint old_page,
+                   gint new_page,
+                   EvPreviewerWindow *window)
+{
+       GtkAction *action;
+       gint       n_pages = ev_document_get_n_pages (ev_document_model_get_document (window->model));
+
+       action = gtk_action_group_get_action (window->action_group, "GoPreviousPage");
+       gtk_action_set_sensitive (GTK_ACTION (action), new_page > 0 );
+
+       action = gtk_action_group_get_action (window->action_group, "GoNextPage");
+       gtk_action_set_sensitive (GTK_ACTION (action), new_page < n_pages - 1);
+}
+
+static void
 view_sizing_mode_changed (EvDocumentModel   *model,
                          GParamSpec        *pspec,
                          EvPreviewerWindow *window)
@@ -599,6 +615,10 @@ ev_previewer_window_constructor (GType                  type,
        ev_view_set_model (window->view, window->model);
        ev_document_model_set_continuous (window->model, FALSE);
 
+       g_signal_connect_object (window->model, "page-changed",
+                                G_CALLBACK (model_page_changed),
+                                window, 0);
+
        gtk_container_add (GTK_CONTAINER (window->swindow), GTK_WIDGET (window->view));
        gtk_widget_show (GTK_WIDGET (window->view));