[evince] libview: Cycle through form fields with tab button

[Carlos Garcia Campos <carlosgc src gnome org>]

commit e3e3f7740a5b5d8ce0d78b6de098a10acfcee853
Author: Andrey Pustovalov <AndreiPustovalov ya ru>
Date:   Thu Mar 13 03:59:24 2014 -0700

    libview: Cycle through form fields with tab button
    
    https://bugzilla.gnome.org/show_bug.cgi?id=503706

 libview/ev-view-private.h |    1 +
 libview/ev-view.c         |  158 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 158 insertions(+), 1 deletions(-)
---
diff --git a/libview/ev-view-private.h b/libview/ev-view-private.h
index 0ff7412..7727bbb 100644
--- a/libview/ev-view-private.h
+++ b/libview/ev-view-private.h
@@ -206,6 +206,7 @@ struct _EvView {
        /* Focus */
        EvMapping *focused_element;
        guint focused_element_page;
+       guint child_focus_idle_id;
 
        /* Synctex */
        EvMapping *synctex_result;
diff --git a/libview/ev-view.c b/libview/ev-view.c
index d33c4a1..51ecd3a 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -2648,8 +2648,11 @@ _ev_view_focus_form_field (EvView      *view,
        }
 
        /* Form field doesn't require a widget */
-       if (!field_widget)
+       if (!field_widget) {
+               if (!gtk_widget_has_focus (GTK_WIDGET (view)))
+                       gtk_widget_grab_focus (GTK_WIDGET (view));
                return;
+       }
 
        g_object_set_data_full (G_OBJECT (field_widget), "form-field",
                                g_object_ref (field),
@@ -2658,6 +2661,7 @@ _ev_view_focus_form_field (EvView      *view,
        form_field_mapping = ev_page_cache_get_form_field_mapping (view->page_cache,
                                                                   field->page->index);
        mapping = ev_mapping_list_find (form_field_mapping, field);
+       _ev_view_set_focused_element (view, mapping, field->page->index);
        ev_view_put_to_doc_rect (view, field_widget, field->page->index, &mapping->area);
        gtk_widget_show (field_widget);
        gtk_widget_grab_focus (field_widget);
@@ -6256,6 +6260,11 @@ ev_view_dispose (GObject *object)
                view->cursor_blink_timeout_id = 0;
        }
 
+       if (view->child_focus_idle_id) {
+               g_source_remove (view->child_focus_idle_id);
+               view->child_focus_idle_id = 0;
+       }
+
         gtk_scrollable_set_hadjustment (GTK_SCROLLABLE (view), NULL);
         gtk_scrollable_set_vadjustment (GTK_SCROLLABLE (view), NULL);
 
@@ -6466,6 +6475,152 @@ add_move_binding_keypad (GtkBindingSet  *binding_set,
                                      G_TYPE_BOOLEAN, TRUE);
 }
 
+static gint
+ev_view_mapping_compare (const EvMapping *a,
+                        const EvMapping *b,
+                        gpointer         user_data)
+{
+       GtkTextDirection text_direction = GPOINTER_TO_INT (user_data);
+       gint y1 = a->area.y1 + (a->area.y2 - a->area.y1) / 2;
+       gint y2 = b->area.y1 + (b->area.y2 - b->area.y1) / 2;
+
+       if (y1 == y2) {
+               gint x1 = a->area.x1 + (a->area.x2 - a->area.x1) / 2;
+               gint x2 = b->area.x1 + (b->area.x2 - b->area.x1) / 2;
+
+               if (text_direction == GTK_TEXT_DIR_RTL)
+                       return (x1 < x2) ? 1 : ((x1 == x2) ? 0 : -1);
+
+               return (x1 < x2) ? -1 : ((x1 == x2) ? 0 : 1);
+       }
+
+       return (y1 < y2) ? -1 : 1;
+}
+
+static GList *
+ev_view_get_sorted_mapping_list (EvView          *view,
+                                GtkDirectionType direction,
+                                gint             page)
+{
+       GList         *mapping_list = NULL, *l;
+       EvMappingList *forms_mapping;
+
+       forms_mapping = ev_page_cache_get_form_field_mapping (view->page_cache, page);
+
+       for (l = ev_mapping_list_get_list (forms_mapping); l; l = g_list_next (l)) {
+               EvMapping   *mapping = (EvMapping *)l->data;
+               EvFormField *field = (EvFormField *)mapping->data;
+
+               if (field->is_read_only || EV_IS_FORM_FIELD_SIGNATURE (field))
+                       continue;
+
+               mapping_list = g_list_prepend (mapping_list, mapping);
+       }
+
+       if (!mapping_list)
+               return NULL;
+
+       mapping_list = g_list_sort_with_data (g_list_reverse (mapping_list),
+                                             (GCompareDataFunc)ev_view_mapping_compare,
+                                             GINT_TO_POINTER (gtk_widget_get_direction (GTK_WIDGET (view))));
+
+       if (direction == GTK_DIR_TAB_BACKWARD)
+               mapping_list = g_list_reverse (mapping_list);
+       return mapping_list;
+}
+
+static gboolean
+child_focus_forward_idle_cb (gpointer user_data)
+{
+       EvView *view = EV_VIEW (user_data);
+
+       view->child_focus_idle_id = 0;
+       gtk_widget_child_focus (GTK_WIDGET (view), GTK_DIR_TAB_FORWARD);
+
+       return G_SOURCE_REMOVE;
+}
+
+static gboolean
+child_focus_backward_idle_cb (gpointer user_data)
+{
+       EvView *view = EV_VIEW (user_data);
+
+       view->child_focus_idle_id = 0;
+       gtk_widget_child_focus (GTK_WIDGET (view), GTK_DIR_TAB_BACKWARD);
+
+       return G_SOURCE_REMOVE;
+}
+
+static void
+schedule_child_focus_in_idle (EvView           *view,
+                             GtkDirectionType  direction)
+{
+       if (view->child_focus_idle_id)
+               g_source_remove (view->child_focus_idle_id);
+       view->child_focus_idle_id =
+               g_idle_add (direction == GTK_DIR_TAB_FORWARD ? child_focus_forward_idle_cb : 
child_focus_backward_idle_cb,
+                           view);
+}
+
+static gboolean
+ev_view_focus_next (EvView           *view,
+                   GtkDirectionType  direction)
+{
+       EvMapping *focus_element;
+       GList     *elements;
+
+       if (view->focused_element) {
+               GList *l;
+
+               elements = ev_view_get_sorted_mapping_list (view, direction, view->focused_element_page);
+               l = g_list_find (elements, view->focused_element);
+               l = g_list_next (l);
+               focus_element = l ? l->data : NULL;
+       } else {
+               elements = ev_view_get_sorted_mapping_list (view, direction, view->current_page);
+               focus_element = elements ? elements->data : NULL;
+       }
+
+       g_list_free (elements);
+
+       if (focus_element) {
+               ev_view_remove_all (view);
+               _ev_view_focus_form_field (view, EV_FORM_FIELD (focus_element->data));
+
+               return TRUE;
+       }
+
+       ev_view_remove_all (view);
+       _ev_view_set_focused_element (view, NULL, -1);
+
+       /* FIXME: this doesn't work if the next/previous page doesn't have form fields */
+       if (direction == GTK_DIR_TAB_FORWARD) {
+               if (ev_view_next_page (view)) {
+                       schedule_child_focus_in_idle (view, direction);
+                       return TRUE;
+               }
+       } else if (direction == GTK_DIR_TAB_BACKWARD) {
+               if (ev_view_previous_page (view)) {
+                       schedule_child_focus_in_idle (view, direction);
+                       return TRUE;
+               }
+       }
+
+       return FALSE;
+}
+
+static gboolean
+ev_view_focus (GtkWidget        *widget,
+              GtkDirectionType  direction)
+{
+       EvView *view = EV_VIEW (widget);
+
+       if (direction == GTK_DIR_TAB_FORWARD || direction == GTK_DIR_TAB_BACKWARD)
+               return ev_view_focus_next (view, direction);
+
+       return GTK_WIDGET_CLASS (ev_view_parent_class)->focus (widget, direction);
+}
+
 static void
 ev_view_class_init (EvViewClass *class)
 {
@@ -6500,6 +6655,7 @@ ev_view_class_init (EvViewClass *class)
        widget_class->popup_menu = ev_view_popup_menu;
        widget_class->query_tooltip = ev_view_query_tooltip;
        widget_class->screen_changed = ev_view_screen_changed;
+       widget_class->focus = ev_view_focus;
 
        container_class->remove = ev_view_remove;
        container_class->forall = ev_view_forall;