add app groups

examples/app_library/grid_item/grid_item.ui

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <template class="GridItem" parent="GtkBox">
+    <property name="orientation">vertical</property>
+    <property name="halign">center</property>
+    <property name="hexpand">true</property>
+    <property name="margin-top">4</property>
+    <property name="margin-end">4</property>
+    <property name="margin-bottom">4</property>
+    <child>
+       <object class="GtkImage" id="image">
+         <property name="margin-top">4</property>
+         <property name="margin-bottom">4</property>
+         <property name="pixel-size">80</property>
+       </object>
+     </child>
+    <child>
+      <object class="GtkLabel" id="name">
+        <property name="halign">center</property>
+        <property name="ellipsize">end</property>
+        <style>
+          <class name="title-5" />
+        </style>
+      </object>
+    </child>
+  </template>
+</interface>

examples/app_library/grid_item/imp.rs

@@ -0,0 +1,34 @@
+use gtk::glib;
+use gtk::prelude::*;
+use gtk::subclass::prelude::*;
+use gtk4 as gtk;
+
+use gtk::CompositeTemplate;
+
+#[derive(Debug, Default, CompositeTemplate)]
+#[template(file = "grid_item.ui")]
+pub struct GridItem {
+    #[template_child]
+    pub name: TemplateChild<gtk::Label>,
+    #[template_child]
+    pub image: TemplateChild<gtk::Image>,
+}
+
+#[glib::object_subclass]
+impl ObjectSubclass for GridItem {
+    const NAME: &'static str = "GridItem";
+    type Type = super::GridItem;
+    type ParentType = gtk::Box;
+
+    fn class_init(klass: &mut Self::Class) {
+        Self::bind_template(klass);
+    }
+
+    fn instance_init(obj: &glib::subclass::InitializingObject<Self>) {
+        obj.init_template();
+    }
+}
+
+impl ObjectImpl for GridItem {}
+impl WidgetImpl for GridItem {}
+impl BoxImpl for GridItem {}

examples/app_library/grid_item/mod.rs

@@ -0,0 +1,50 @@
+use crate::app_group::AppGroup;
+use gtk4 as gtk;
+mod imp;
+
+use gtk::prelude::*;
+use gtk::subclass::prelude::*;
+use gtk::{gio, glib};
+
+glib::wrapper! {
+    pub struct GridItem(ObjectSubclass<imp::GridItem>)
+        @extends gtk::Widget, gtk::Box;
+}
+
+impl Default for GridItem {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl GridItem {
+    pub fn new() -> Self {
+        glib::Object::new(&[]).expect("Failed to create GridItem")
+    }
+
+    pub fn set_app_info(&self, app_info: &gio::DesktopAppInfo) {
+        let self_ = imp::GridItem::from_instance(self);
+        self_.name.set_text(&app_info.name());
+        if let Some(icon) = app_info.icon() {
+            self_.image.set_from_gicon(&icon);
+        }
+    }
+
+    pub fn set_group_info(&self, app_group: AppGroup) {
+        let self_ = imp::GridItem::from_instance(self);
+        if let Ok(name) = app_group.property("name") {
+            self_.name.set_text(
+                &name
+                    .get::<String>()
+                    .expect("property name needs to be a string."),
+            );
+        }
+        if let Ok(icon) = app_group.property("icon") {
+            &self_.image.set_from_icon_name(Some(
+                &icon
+                    .get::<String>()
+                    .expect("Property name needs to be a String."),
+            ));
+        }
+    }
+}