Add simple example about DBus signals

Author: swsnr

examples/Cargo.toml

@@ -36,6 +36,10 @@ path = "gio_futures/main.rs"
 name = "gio_futures_await"
 path = "gio_futures_await/main.rs"
 
+[[bin]]
+name = "gio_dbus_receive_signals"
+path = "gio_dbus_receive_signals/main.rs"
+
 [[bin]]
 name = "gio_dbus_register_object"
 path = "gio_dbus_register_object/main.rs"

examples/gio_dbus_receive_signals/main.rs

@@ -0,0 +1,105 @@
+use gio::prelude::*;
+
+glib::wrapper! {
+    pub struct SampleApplication(ObjectSubclass<imp::SampleApplication>)
+        @extends gio::Application,
+        @implements gio::ActionGroup, gio::ActionMap;
+}
+
+impl Default for SampleApplication {
+    fn default() -> Self {
+        glib::Object::builder()
+            .property(
+                "application-id",
+                "com.github.gtk-rs.examples.ReceiveDBusSignals",
+            )
+            .build()
+    }
+}
+
+mod imp {
+    use std::cell::RefCell;
+
+    use futures::{future, StreamExt};
+    use gio::prelude::*;
+    use gio::subclass::prelude::*;
+    use gio::{bus_get_future, BusType, DBusSignalFlags, WeakSignalSubscription};
+
+    const DESKTOP_PORTAL_BUSNAME: &str = "org.freedesktop.portal.Desktop";
+    const DESKTOP_PORTAL_OBJPATH: &str = "/org/freedesktop/portal/desktop";
+    const SETTINGS_PORTAL_IFACE: &str = "org.freedesktop.portal.Settings";
+
+    #[derive(Default)]
+    pub struct SampleApplication {
+        signal_subscription: RefCell<Option<WeakSignalSubscription>>,
+    }
+
+    #[glib::object_subclass]
+    impl ObjectSubclass for SampleApplication {
+        const NAME: &'static str = "SampleApplication";
+
+        type Type = super::SampleApplication;
+
+        type ParentType = gio::Application;
+    }
+
+    impl ObjectImpl for SampleApplication {}
+
+    impl ApplicationImpl for SampleApplication {
+        fn startup(&self) {
+            self.parent_startup();
+
+            self.signal_subscription.replace(Some(
+                self.obj()
+                    .dbus_connection()
+                    .unwrap()
+                    .subscribe_to_signal(
+                        Some(DESKTOP_PORTAL_BUSNAME),
+                        Some(SETTINGS_PORTAL_IFACE),
+                        Some("SettingChanged"),
+                        Some(DESKTOP_PORTAL_OBJPATH),
+                        None,
+                        DBusSignalFlags::NONE,
+                        |signal| {
+                            println!(
+                                "Callback received signal {}.{} from {} at {} with parameters: {}",
+                                signal.interface_name,
+                                signal.signal_name,
+                                signal.object_path,
+                                signal.sender_name,
+                                signal.parameters
+                            )
+                        },
+                    )
+                    .downgrade(),
+            ));
+
+            glib::spawn_future_local(async move {
+                let session_bus = bus_get_future(BusType::Session).await.unwrap();
+                session_bus
+                    .receive_signal_parameters::<(String, String, glib::Variant)>(
+                        Some(DESKTOP_PORTAL_BUSNAME),
+                        Some(SETTINGS_PORTAL_IFACE),
+                        Some("SettingChanged"),
+                        Some(DESKTOP_PORTAL_OBJPATH),
+                        None,
+                        DBusSignalFlags::NONE,
+                    )
+                    .for_each(|result| {
+                        let (iface, setting, value) = result.unwrap();
+                        println!("Setting {iface}.{setting} changed to {value}");
+                        future::ready(())
+                    })
+                    .await
+            });
+        }
+
+        fn activate(&self) {}
+    }
+}
+
+fn main() -> glib::ExitCode {
+    let app = SampleApplication::default();
+    let _guard = app.hold();
+    app.run()
+}