[evince/294-cannot-select-default-option-in-form-drop-down-box] ev-view: fix ComboBoxText user selected item's logic

[Nelson Benítez León <nbenitez src gnome org>]

commit c985647ab9d71f44f0861bd8b938a846b1f8f17b
Author: Nelson Benítez León <nbenitezl gmail com>
Date:   Sun Oct 28 13:01:26 2018 +0500

    ev-view: fix ComboBoxText user selected item's logic
    
    so that:
    
     - we don't force the first item as default, i.e.
       permit the user to dismiss the dialog without
       select any option.
    
     - detect when user didn't select any option or
       selected the already active option, as we also
       need to remove combobox in those cases. This both
       cases couldn't be detected with GtkComboBox "changed"
       signal, that's why we have to use "notify::popup-shown"
       for that.
    
      Fixes issue #294

 libview/ev-view.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 54 insertions(+), 9 deletions(-)
---
diff --git a/libview/ev-view.c b/libview/ev-view.c
index 219ee9f9..aa880bb9 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -2573,8 +2573,8 @@ ev_view_form_field_choice_changed (GtkWidget   *widget,
                gint item;
                
                item = gtk_combo_box_get_active (GTK_COMBO_BOX (widget));
-               if (!field_choice->selected_items ||
-                   GPOINTER_TO_INT (field_choice->selected_items->data) != item) {
+               if (item != -1 && (!field_choice->selected_items ||
+                   GPOINTER_TO_INT (field_choice->selected_items->data) != item)) {
                        g_list_free (field_choice->selected_items);
                        field_choice->selected_items = NULL;
                        field_choice->selected_items = g_list_prepend (field_choice->selected_items,
@@ -2622,6 +2622,53 @@ ev_view_form_field_choice_changed (GtkWidget   *widget,
        }
 }
 
+typedef struct _PopupShownData {
+       GtkWidget   *choice;
+       EvFormField *field;
+       EvView      *view;
+} PopupShownData;
+
+static gboolean
+ev_view_form_field_choice_popup_shown_real (PopupShownData *data)
+{
+       ev_view_form_field_choice_changed (data->choice, data->field);
+       ev_view_form_field_destroy (data->choice, data->view);
+
+       g_object_unref (data->choice);
+       g_object_unref (data->field);
+       g_free (data);
+
+       return FALSE;
+}
+
+static void
+ev_view_form_field_choice_popup_shown_cb (GObject    *self,
+                                         GParamSpec *pspec,
+                                         gpointer    user_data)
+{
+       EvView *view;
+       EvFormField *field;
+       GtkWidget *choice;
+       gboolean shown;
+       PopupShownData *data;
+
+       g_object_get (self, "popup-shown", &shown, NULL);
+       if (shown)
+               return; /* popup has been opened */
+
+       /* Popup has been closed */
+       field = g_object_get_data (self, "form-field");
+       choice = GTK_WIDGET (self);
+       view = EV_VIEW (user_data);
+
+       data = g_new0 (PopupShownData, 1);
+       data->choice = g_object_ref (choice);
+       data->field = g_object_ref (field);
+       data->view = view;
+       /* We need to use an idle here because combobox "active" item is not updated yet */
+       g_idle_add ((GSourceFunc) ev_view_form_field_choice_popup_shown_real, (gpointer) data);
+}
+
 static GtkWidget *
 ev_view_form_field_choice_create_widget (EvView      *view,
                                         EvFormField *field)
@@ -2630,7 +2677,7 @@ ev_view_form_field_choice_create_widget (EvView      *view,
        GtkWidget         *choice;
        GtkTreeModel      *model;
        gint               n_items, i;
-       gint               selected_item = 0;
+       gint               selected_item = -1;
 
        n_items = ev_document_forms_form_field_choice_get_n_items (EV_DOCUMENT_FORMS (view->document),
                                                                   field);
@@ -2729,12 +2776,10 @@ ev_view_form_field_choice_create_widget (EvView      *view,
                gtk_combo_box_set_active (GTK_COMBO_BOX (choice), selected_item);
                gtk_combo_box_popup (GTK_COMBO_BOX (choice));
                
-               g_signal_connect (choice, "changed",
-                                 G_CALLBACK (ev_view_form_field_choice_changed),
-                                 field);
-               g_signal_connect_after (choice, "changed",
-                                       G_CALLBACK (ev_view_form_field_destroy),
-                                       view);
+               /* See issue #294 for why we use this instead of "changed" signal */
+               g_signal_connect (G_OBJECT (choice), "notify::popup-shown",
+                                 G_CALLBACK (ev_view_form_field_choice_popup_shown_cb),
+                                 view);
        }
 
        g_object_unref (model);