move starting of GLib event loop into libwebrtc crate

Downstream applications should not have to be concerned with this
implementation detail. If they want to disable the automatic start
of the GLib main loop, they can opt out by disabling the
glib-main-loop feature.

Author: Be-ing

examples/screensharing/Cargo.toml

@@ -11,6 +11,3 @@ livekit-api = { path = "../../livekit-api"}
 log = "0.4"
 clap = { version = "4.0", features = ["derive"] }
 inquire = "0.9"
-
-[target.'cfg(target_os = "linux")'.dependencies]
-glib = "0.21.1"

examples/screensharing/src/main.rs

@@ -42,18 +42,6 @@ async fn main() {
         .init();
     let args = Args::parse();
 
-    // On Wayland, libwebrtc communicates with the XDG Desktop Portal over dbus using GDBus
-    // from the gio library. This requires a running glib event loop to work.
-    // If your application already has a glib event loop running for another reason, for
-    // example using the GTK or GStreamer Rust bindings, you do not need to setup another
-    // glib event loop for this.
-    if cfg!(target_os = "linux") && std::env::var("WAYLAND_DISPLAY").is_ok() {
-        let main_loop = glib::MainLoop::new(None, false);
-        let _handle = std::thread::spawn(move || {
-            main_loop.run();
-        });
-    }
-
     let url = env::var("LIVEKIT_URL").expect("LIVEKIT_URL is not set");
     let api_key = env::var("LIVEKIT_API_KEY").expect("LIVEKIT_API_KEY is not set");
     let api_secret = env::var("LIVEKIT_API_SECRET").expect("LIVEKIT_API_SECRET is not set");

libwebrtc/Cargo.toml

@@ -7,13 +7,25 @@ license = "Apache-2.0"
 description = "Livekit safe bindings to libwebrtc"
 repository = "https://github.com/livekit/rust-sdks"
 
+[features]
+default = [ "glib-main-loop" ]
+# On Wayland, libwebrtc communicates with the XDG Desktop Portal over dbus using GDBus
+# from the gio library. This requires a running glib event loop to work.
+# If your application already has a glib event loop running for another reason, for
+# example using the GTK or GStreamer Rust bindings, it does not need to setup another
+# glib event loop for this and can opt out by disabling this default glib-main-loop feature.
+glib-main-loop = [ "dep:glib" ]
+
 [dependencies]
 livekit-protocol = { workspace = true }
 log = "0.4"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 thiserror = "1.0"
 
+[target.'cfg(target_os = "linux")'.dependencies]
+glib = { version = "0.21.3", optional = true }
+
 [target.'cfg(target_os = "android")'.dependencies]
 jni = "0.21"
 

libwebrtc/src/native/desktop_capturer.rs

@@ -145,6 +145,13 @@ impl DesktopCapturer {
     }
 
     pub fn start(&mut self) {
+        #[cfg(all(target_os = "linux", feature = "glib-main-loop"))]
+        if std::env::var("WAYLAND_DISPLAY").is_ok() {
+            let main_loop = glib::MainLoop::new(None, false);
+            let _handle = std::thread::spawn(move || {
+                main_loop.run();
+            });
+        }
         let pin_handle = self.sys_handle.pin_mut();
         pin_handle.start();
     }