client: Add a GTK example

wayland-client/Cargo.toml

@@ -25,3 +25,6 @@ log = { version = "0.4", optional = true }
 wayland-protocols = { path = "../wayland-protocols", features = ["client"] }
 futures-util = "0.3"
 tempfile = "3.2"
+gtk4 = { version = "0.4.8" }
+gdk4-wayland = { version = "0.4.8", features = ["wayland_crate", "v4_4", "egl"] }
+wayland-backend = { path = "../wayland-backend", features = ["client_system"] }

wayland-client/examples/gtk_list_globals.rs

@@ -0,0 +1,76 @@
+use gtk4::{gdk, glib, prelude::*};
+use std::{collections::HashMap, future::poll_fn, os::unix::io::AsRawFd};
+use wayland_client::{backend::Backend, protocol::wl_registry, Connection, Dispatch, QueueHandle};
+
+struct State {
+    list_box: gtk4::ListBox,
+    rows: HashMap<u32, gtk4::Label>,
+}
+
+impl Dispatch<wl_registry::WlRegistry, ()> for State {
+    fn event(
+        state: &mut Self,
+        _: &wl_registry::WlRegistry,
+        event: wl_registry::Event,
+        _: &(),
+        _: &Connection,
+        _: &QueueHandle<State>,
+    ) {
+        match event {
+            wl_registry::Event::Global { name, interface, version } => {
+                // Add a row for the global to the `ListBox`
+                let text = format!("[{}] {} (v{})", name, interface, version);
+                let row = gtk4::Label::new(Some(&text));
+                row.set_halign(gtk4::Align::Start);
+                state.list_box.append(&row);
+            }
+            wl_registry::Event::GlobalRemove { name } => {
+                // Remove the global's row from the `ListBox`
+                let row = state.rows.remove(&name).unwrap();
+                state.list_box.remove(&row);
+            }
+            _ => {}
+        }
+    }
+}
+
+fn main() {
+    // Initialize GTK
+    gtk4::init().unwrap();
+
+    // Create a GTK window with an empty `ListBox`
+    let list_box = gtk4::ListBox::new();
+    let window = gtk4::Window::new();
+    window.set_child(Some(&list_box));
+    window.show();
+
+    // Create a connection from the `GdkWaylandDisplay`
+    let display =
+        gdk::Display::default().unwrap().downcast::<gdk4_wayland::WaylandDisplay>().unwrap();
+    let wl_display = display.wl_display().c_ptr();
+    let connection =
+        Connection::from_backend(unsafe { Backend::from_foreign_display(wl_display as _) });
+
+    // Create an event queue and get registry GTK doesn't provide a way to get
+    // registry events from its copy.
+    let mut event_queue = connection.new_event_queue();
+    let qh = event_queue.handle();
+    let _registry = connection.display().get_registry(&qh, ());
+
+    // Read from connection
+    let fd = connection.prepare_read().unwrap().connection_fd().as_raw_fd();
+    glib::source::unix_fd_add_local(fd, glib::IOCondition::IN, move |_, _| {
+        connection.prepare_read().unwrap().read().unwrap();
+        glib::Continue(true)
+    });
+
+    // Dispatch events when reads occur. Async version must be used since
+    // GTK's types aren't thread safe.
+    let mut state = State { list_box, rows: HashMap::new() };
+    glib::MainContext::default().spawn_local(async move {
+        poll_fn(|cx| event_queue.poll_dispatch_pending(cx, &mut state)).await.unwrap();
+    });
+
+    // Run GLib main loop
+    glib::MainLoop::new(None, false).run();
+}