[gnome-initial-setup/wip/pwithnall/misc-fixes: 29/70] language-chooser: make it more clear for the users

[Philip Withnall <pwithnall src gnome org>]

commit 52429d89b8a047792deb9b381033a8b26b822f10
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Feb 6 15:36:56 2017 -0200

    language-chooser: make it more clear for the users
    
    What this patch implements:
        - vertically centralize the selected language to ensure
        that the initially selected language is shown.
        - show all languages by default because it is not clear that
        the three-vertical-dots row means "show the other languages".
        Instead of simply setting a field, go through the method that would
        be used when clicking on the dots. This will make sure the internal
        state stays consistent, including the visibility of the vertical
        scrollbar.
        - show the searchbar by default because all languages are shown
        by default.
    
    (Modified during the 3.36 rebase by Matthew Leeds to drop "<property
    name="valign">fill</property>" on the box id "box" in
    gis-language-page.ui. See upstream commit bdca72d6c)
    (Rebase 3.38: This could potentially be dropped in future if we update
    cc-language-chooser.c from gnome-control-center; it’s copy/paste code.)
    
    https://phabricator.endlessm.com/T15310
    https://phabricator.endlessm.com/T17323

 .../pages/language/cc-language-chooser.c           | 68 +++++++++++++++++++++-
 .../pages/language/gis-language-page.ui            |  1 -
 .../pages/language/language-chooser.ui             |  2 +-
 3 files changed, 67 insertions(+), 4 deletions(-)
---
diff --git a/gnome-initial-setup/pages/language/cc-language-chooser.c 
b/gnome-initial-setup/pages/language/cc-language-chooser.c
index fa8531cc..2e15331c 100644
--- a/gnome-initial-setup/pages/language/cc-language-chooser.c
+++ b/gnome-initial-setup/pages/language/cc-language-chooser.c
@@ -42,6 +42,9 @@ struct _CcLanguageChooserPrivate
         GtkWidget *filter_entry;
         GtkWidget *language_list;
 
+        GtkWidget *to_be_scrolled_row;
+        gboolean initial_scroll;
+
         GtkWidget *scrolled_window;
         GtkWidget *no_results;
         GtkWidget *more_item;
@@ -188,10 +191,65 @@ language_widget_new (const char *locale_id,
         return widget->box;
 }
 
+static inline gint
+get_selected_language_row_y (GtkWidget *row)
+{
+        GtkAllocation alloc;
+
+        gtk_widget_get_allocation (row, &alloc);
+
+        return alloc.y + alloc.height / 2.0;
+}
+
+static void
+update_scroll_position (CcLanguageChooser *chooser)
+{
+        CcLanguageChooserPrivate *priv = cc_language_chooser_get_instance_private (chooser);
+        GtkAdjustment *vadjustment;
+        GtkWidget *row;
+        gdouble page_increment;
+        gdouble real_value;
+
+        row = priv->to_be_scrolled_row;
+
+        vadjustment = gtk_scrolled_window_get_vadjustment (GTK_SCROLLED_WINDOW (priv->scrolled_window));
+        page_increment = gtk_adjustment_get_page_increment (vadjustment);
+        real_value = get_selected_language_row_y (row) - page_increment / 2.0;
+
+        /*
+         * Since GtkScrolledWindow tries to follow the focused row of a listbox,
+         * make sure that the current row is focused.
+         */
+        gtk_widget_grab_focus (row);
+
+        gtk_adjustment_set_value (vadjustment, real_value);
+
+        priv->initial_scroll = TRUE;
+}
+
+static void
+schedule_scroll (CcLanguageChooser *chooser,
+                 GtkWidget         *row)
+{
+        CcLanguageChooserPrivate *priv = cc_language_chooser_get_instance_private (chooser);
+        priv->to_be_scrolled_row = row;
+
+        if (gtk_widget_get_realized (priv->scrolled_window)) {
+                update_scroll_position (chooser);
+                return;
+        }
+
+        g_signal_connect_swapped (priv->scrolled_window,
+                                  "realize",
+                                  G_CALLBACK (update_scroll_position),
+                                  chooser);
+}
+
 static void
 sync_checkmark (GtkWidget *row,
                 gpointer   user_data)
 {
+        CcLanguageChooser *chooser;
         GtkWidget *child;
         LanguageWidget *widget;
         gchar *locale_id;
@@ -203,9 +261,14 @@ sync_checkmark (GtkWidget *row,
         if (widget == NULL)
                 return;
 
-        locale_id = user_data;
+        chooser = user_data;
+        CcLanguageChooserPrivate *priv = cc_language_chooser_get_instance_private (chooser);
+        locale_id = priv->language;
         should_be_visible = g_str_equal (widget->locale_id, locale_id);
         gtk_widget_set_opacity (widget->checkmark, should_be_visible ? 1.0 : 0.0);
+
+        if (should_be_visible && !priv->initial_scroll)
+                schedule_scroll (chooser, row);
 }
 
 static void
@@ -214,7 +277,7 @@ sync_all_checkmarks (CcLanguageChooser *chooser)
         CcLanguageChooserPrivate *priv = cc_language_chooser_get_instance_private (chooser);
 
         gtk_container_foreach (GTK_CONTAINER (priv->language_list),
-                               sync_checkmark, priv->language);
+                               sync_checkmark, chooser);
 }
 
 static GtkWidget *
@@ -504,6 +567,7 @@ cc_language_chooser_constructed (GObject *object)
                 priv->language = cc_common_language_get_current_language ();
 
         sync_all_checkmarks (chooser);
+        show_more (chooser);
 }
 
 static void
diff --git a/gnome-initial-setup/pages/language/gis-language-page.ui 
b/gnome-initial-setup/pages/language/gis-language-page.ui
index 8f2a08cf..1ebbf9b4 100644
--- a/gnome-initial-setup/pages/language/gis-language-page.ui
+++ b/gnome-initial-setup/pages/language/gis-language-page.ui
@@ -37,7 +37,6 @@
             <property name="margin_bottom">18</property>
             <property name="width_request">400</property>
             <property name="visible">True</property>
-            <property name="valign">start</property>
           </object>
         </child>
       </object>
diff --git a/gnome-initial-setup/pages/language/language-chooser.ui 
b/gnome-initial-setup/pages/language/language-chooser.ui
index fc61d597..986dcfe2 100644
--- a/gnome-initial-setup/pages/language/language-chooser.ui
+++ b/gnome-initial-setup/pages/language/language-chooser.ui
@@ -24,7 +24,7 @@
     </child>
     <child>
       <object class="GtkSearchEntry" id="filter_entry">
-        <property name="visible">False</property>
+        <property name="visible">True</property>
         <property name="hexpand">True</property>
       </object>
     </child>