App architecture modifications.

Now GUI and the app itself is divided into two different binaries.
The app also provides system tray icon.
Whereas the GUI can be used to configure the app.

app/src/tray.rs

@@ -0,0 +1,95 @@
+mod menu;
+
+use tray_icon::{
+    menu::{AboutMetadata, Menu, MenuEvent, MenuItem, PredefinedMenuItem},
+    TrayEvent, TrayIconBuilder,
+};
+use winit::event_loop::{ControlFlow, EventLoopBuilder};
+use image;
+use winit::platform::windows::EventLoopBuilderExtWindows;
+
+use crate::config;
+
+pub fn init() {
+    // spawn tray icon
+    // New thread will prevent tray icon to work on MacOS
+    // @TODO: MacOS support.
+    std::thread::spawn(|| {
+
+        // load tray icon
+        let icon_path = format!("{}/icons/{}", env!("CARGO_MANIFEST_DIR"), config::TRAY_ICON);
+        let icon = load_icon(std::path::Path::new(&icon_path));
+
+        // form tray menu
+        let tray_menu = Menu::with_items(&[
+            &MenuItem::new("Перезапуск", true, None),
+            &MenuItem::new("Настройки", true, None),
+            &MenuItem::new("Выход", true, None)
+        ]);
+
+        #[cfg(not(target_os = "linux"))]
+        let mut tray_icon = Some(
+            TrayIconBuilder::new()
+                .with_menu(Box::new(tray_menu))
+                .with_tooltip(config::TRAY_TOOLTIP)
+                .with_icon(icon)
+                .build()
+                .unwrap()
+        );
+
+        // Since winit doesn't use gtk on Linux, and we need gtk for
+        // the tray icon to show up, we need to initialize gtk and create the tray_icon
+        #[cfg(target_os = "linux")]
+        {
+            use tray_icon::menu::Menu;
+
+            gtk::init().unwrap();
+            let _tray_icon = TrayIconBuilder::new()
+                .with_menu(Box::new(tray_menu))
+                .with_tooltip(config::TRAY_TOOLTIP)
+                .with_icon(icon)
+                .build()
+                .unwrap();
+
+            gtk::main();
+        }
+
+        // run the event loop
+        let event_loop = EventLoopBuilder::new().with_any_thread(true).build();
+
+        let menu_channel = MenuEvent::receiver();
+        let tray_channel = TrayEvent::receiver();
+
+        event_loop.run(move |_event, _, control_flow| {
+            *control_flow = ControlFlow::Poll;
+
+            //if let Ok(event) = tray_channel.try_recv() {
+            //    println!("tray event: {event:?}");
+            //}
+
+            if let Ok(event) = menu_channel.try_recv() {
+                println!("menu event: {:?}", event);
+
+                if event.id == 1002 {
+                    std::process::exit(0);
+                }
+            }
+        });
+
+    });
+
+    info!("Tray initialized.");
+}
+
+fn load_icon(path: &std::path::Path) -> tray_icon::icon::Icon {
+    let (icon_rgba, icon_width, icon_height) = {
+        let image = image::open(path)
+            .expect("Failed to open icon path")
+            .into_rgba8();
+        let (width, height) = image.dimensions();
+        let rgba = image.into_raw();
+        (rgba, width, height)
+    };
+    tray_icon::icon::Icon::from_rgba(icon_rgba, icon_width, icon_height)
+        .expect("Failed to open icon")
+}