library: Port Avatar demo to Rust (#805)

Co-authored-by: Hofer-Julian <30049909+Hofer-Julian@users.noreply.github.com>

Author: theCapypara

src/Library/demos/Avatar/code.rs

@@ -0,0 +1,38 @@
+use crate::workbench;
+use adw::prelude::*;
+use gtk::{gdk, gio, glib};
+
+pub fn main() {
+    gtk::init().unwrap();
+
+    let button: gtk::Button = workbench::builder().object("button").unwrap();
+
+    let mut filter = gtk::FileFilter::new();
+    filter.set_name(Some("Images"));
+    filter.add_pixbuf_formats();
+
+    let dialog = gtk::FileDialog::builder()
+        .title("Select an Avatar")
+        .modal(true)
+        .default_filter(&filter)
+        .build();
+
+    button.connect_clicked(move |_| {
+        dialog.open(
+            Some(workbench::window()),
+            None::<&gio::Cancellable>,
+            on_clicked,
+        )
+    });
+}
+
+fn on_clicked(result: Result<gio::File, glib::Error>) {
+    match result {
+        Ok(file) => {
+            let avatar_image: adw::Avatar = workbench::builder().object("avatar_image").unwrap();
+            let texture = gdk::Texture::from_file(&file).unwrap();
+            avatar_image.set_custom_image(Some(&texture));
+        }
+        Err(err) => eprintln!("Could not load avatar image: {err}."),
+    }
+}