Add BackButton

.github/workflows/main.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Install Dependencies
         run: |
           apt update
-          apt install -y meson gobject-introspection libgee-0.8-dev libgirepository1.0-dev libgtk-4-dev sassc valac
+          apt install -y meson gobject-introspection libgee-0.8-dev libgirepository1.0-dev libgtk-4-dev libadwaita-1-dev sassc valac
       - name: Build
         env:
           DESTDIR: out

README.md

@@ -15,6 +15,7 @@ You'll need the following dependencies:
 * libgee-0.8-dev
 * libgirepository1.0-dev
 * libgtk-4-dev >= 4.4.0
+* libadwaita-1-dev >= 1.4
 * sassc
 * valac
 

demo/Views/CSSView.vala

@@ -70,12 +70,12 @@ public class CSSView : Gtk.Box {
         };
         terminal_scroll.add_css_class (Granite.STYLE_CLASS_TERMINAL);
 
-        var back_button_label = new Granite.HeaderLabel ("\"back-button\" style class") ;
+        var back_button_label = new Granite.HeaderLabel ("BackButton") ;
 
-        var back_button = new Gtk.Button.with_label ("Back Button") {
-            halign = Gtk.Align.START
+        var back_button = new Granite.BackButton () {
+            halign = START,
+            label = "Back"
         };
-        back_button.add_css_class (Granite.STYLE_CLASS_BACK_BUTTON);
 
         var scales_header = new Granite.HeaderLabel ("Scales") {
             secondary_text = "\"warmth\" and \"temperature\" style classes"

lib/Constants.vala

@@ -11,6 +11,7 @@ namespace Granite {
     /**
      * Style class for shaping a {@link Gtk.Button}
      */
+    [Version (deprecated = true, deprecated_since = "7.5.0", replacement = "Granite.BackButton")]
     public const string STYLE_CLASS_BACK_BUTTON = "back-button";
     /**
      * Style class to match the window background

lib/Widgets/BackButton.vala

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2024 elementary, Inc. (https://elementary.io)
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+/**
+ * BackButton is meant to be used in headers to navigate in
+ * {@link Adw.NavigationView}s. It will automatically detect when under a
+ * {@link Adw.NavigationView} and label itself with the title of the preceding page.
+ */
+[Version (since = "7.5.0")]
+public class Granite.BackButton : Gtk.Button {
+    /**
+     * A manually set label when used outside of {@link Adw.NavigationView}
+     */
+    public new string label { get; set; }
+
+    private Binding? title_binding = null;
+
+    construct {
+        var image = new Gtk.Image.from_icon_name ("go-previous-symbolic");
+
+        var label_widget = new Gtk.Label ("");
+
+        var box = new Gtk.Box (HORIZONTAL, 0);
+        box.append (image);
+        box.append (label_widget);
+
+        child = box;
+
+        map.connect (on_map);
+        clicked.connect (on_click);
+
+        bind_property ("label", label_widget, "label");
+    }
+
+    private void on_map () {
+        if (title_binding != null) {
+            title_binding.unbind ();
+        }
+
+        var navigation_view = (Adw.NavigationView) get_ancestor (typeof (Adw.NavigationView));
+
+        if (navigation_view == null) {
+            return;
+        }
+
+        var navigation_page = (Adw.NavigationPage) get_ancestor (typeof (Adw.NavigationPage));
+
+        if (navigation_view == null) {
+            return;
+        }
+
+        var previous_page = navigation_view.get_previous_page (navigation_page);
+
+        if (previous_page != null) {
+            title_binding = previous_page.bind_property ("title", this, "label", SYNC_CREATE);
+        }
+    }
+
+    private void on_click () {
+        var navigation_view = (Adw.NavigationView) get_ancestor (typeof (Adw.NavigationView));
+
+        if (navigation_view != null) {
+            navigation_view.pop ();
+        }
+    }
+}

lib/meson.build

@@ -16,6 +16,7 @@ libgranite_sources = files(
     'Widgets/AbstractSettingsPage.vala',
     'Widgets/AbstractSimpleSettingsPage.vala',
     'Widgets/AccelLabel.vala',
+    'Widgets/BackButton.vala',
     'Widgets/DatePicker.vala',
     'Widgets/Dialog.vala',
     'Widgets/HeaderLabel.vala',

meson.build

@@ -50,6 +50,7 @@ libgranite_deps = [
     dependency('glib-2.0', version: '>=' + glib_min_version),
     dependency('gobject-2.0', version: '>=' + glib_min_version),
     dependency('gtk4', version: '>=4.4'),
+    dependency('libadwaita-1', version: '>=1.4'),
 ]
 
 icons_dir = join_paths(