example: Use a HdyHeaderGroup

This automatically updates the headerbars' window decoration layout.

examples/example-window.c

@@ -6,8 +6,8 @@ struct _ExampleWindow
 {
   GtkApplicationWindow parent_instance;
 
+  HdyLeaflet *header_box;
   HdyLeaflet *content_box;
-  GtkHeaderBar *header_bar;
   GtkButton *back;
   GtkStackSidebar *sidebar;
   GtkStack *stack;
@@ -15,6 +15,7 @@ struct _ExampleWindow
   HdyDialer *dialer;
   GtkLabel *display;
   GtkWidget *arrows;
+  HdyHeaderGroup *header_group;
   GtkAdjustment *adj_arrows_count;
   GtkAdjustment *adj_arrows_duration;
 };
@@ -38,6 +39,33 @@ example_window_key_pressed_cb (GtkWidget     *sender,
   return FALSE;
 }
 
+static void
+update (ExampleWindow *self)
+{
+  GtkWidget *header_child = hdy_leaflet_get_visible_child (self->header_box);
+  HdyFold fold = hdy_leaflet_get_fold (self->header_box);
+
+  g_assert (header_child == NULL || GTK_IS_HEADER_BAR (header_child));
+
+  hdy_header_group_set_focus (self->header_group, fold == HDY_FOLD_FOLDED ? header_child : NULL);
+}
+
+static void
+example_window_notify_header_visible_child_cb (GObject       *sender,
+                                               GParamSpec    *pspec,
+                                               ExampleWindow *self)
+{
+  update (self);
+}
+
+static void
+example_window_notify_fold_cb (GObject       *sender,
+                                 GParamSpec    *pspec,
+                                 ExampleWindow *self)
+{
+  update (self);
+}
+
 static void
 example_window_notify_visible_child_cb (GObject       *sender,
                                         GParamSpec    *pspec,
@@ -219,8 +247,8 @@ example_window_class_init (ExampleWindowClass *klass)
   object_class->constructed = example_window_constructed;
 
   gtk_widget_class_set_template_from_resource (widget_class, "/sm/puri/handy/example/ui/example-window.ui");
+  gtk_widget_class_bind_template_child (widget_class, ExampleWindow, header_box);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, content_box);
-  gtk_widget_class_bind_template_child (widget_class, ExampleWindow, header_bar);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, back);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, sidebar);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, stack);
@@ -228,9 +256,12 @@ example_window_class_init (ExampleWindowClass *klass)
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, dialer);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, display);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, arrows);
+  gtk_widget_class_bind_template_child (widget_class, ExampleWindow, header_group);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, adj_arrows_count);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, adj_arrows_duration);
   gtk_widget_class_bind_template_callback_full (widget_class, "key_pressed_cb", G_CALLBACK(example_window_key_pressed_cb));
+  gtk_widget_class_bind_template_callback_full (widget_class, "notify_header_visible_child_cb", G_CALLBACK(example_window_notify_header_visible_child_cb));
+  gtk_widget_class_bind_template_callback_full (widget_class, "notify_fold_cb", G_CALLBACK(example_window_notify_fold_cb));
   gtk_widget_class_bind_template_callback_full (widget_class, "notify_visible_child_cb", G_CALLBACK(example_window_notify_visible_child_cb));
   gtk_widget_class_bind_template_callback_full (widget_class, "back_clicked_cb", G_CALLBACK(example_window_back_clicked_cb));
   gtk_widget_class_bind_template_callback_full (widget_class, "submitted_cb", G_CALLBACK(example_window_submitted_cb));

examples/example-window.ui

@@ -33,12 +33,14 @@
             <property name="mode-transition-type">slide</property>
             <property name="child-transition-type">slide</property>
             <property name="visible-child-name" bind-source="content_box" bind-property="visible-child-name" bind-flags="sync-create"/>
+            <signal name="notify::visible-child" handler="notify_header_visible_child_cb" swapped="no"/>
+            <signal name="notify::fold" handler="notify_fold_cb" after="yes" swapped="no"/>
             <child>
               <object class="GtkHeaderBar" id="header_bar">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
                 <property name="title">Handy Widget Factory</property>
-                <property name="show_close_button" bind-source="header_box" bind-property="folded" bind-flags="sync-create"/>
+                <property name="show_close_button">True</property>
               </object>
               <packing>
                 <property name="name">sidebar</property>
@@ -671,6 +673,12 @@
       <widget name="stack"/>
     </widgets>
   </object>
+  <object class="HdyHeaderGroup" id="header_group">
+    <headerbars>
+      <headerbar name="header_bar"/>
+      <headerbar name="sub_header_bar"/>
+    </headerbars>
+  </object>
   <object class="GtkAdjustment" id="column_width_adjustment">
     <property name="lower">0</property>
     <property name="upper">10000</property>