ipc: Add pw_node_id to PipeWire Casts

niri-ipc/src/lib.rs

@@ -1509,6 +1509,11 @@ pub struct Cast {
     ///
     /// Currently, only wlr-screencopy screencasts can have a pid.
     pub pid: Option<i32>,
+    /// PipeWire node ID of the screencast stream.
+    ///
+    /// This is `None` for wlr-screencopy casts, and also for PipeWire casts before the node is
+    /// created (when the cast is just starting up).
+    pub pw_node_id: Option<u32>,
 }
 
 /// Kind of screencast.

src/ipc/client.rs

@@ -768,6 +768,10 @@ fn print_cast(cast: &Cast) {
     if let Some(pid) = cast.pid {
         println!("  PID: {pid}");
     }
+
+    if let Some(node_id) = cast.pw_node_id {
+        println!("  PipeWire node ID: {node_id}");
+    }
 }
 
 fn fmt_rounded(x: f64) -> String {

src/ipc/server.rs

@@ -830,6 +830,7 @@ impl State {
                         is_dynamic_target: true,
                         is_active: false,
                         pid: None,
+                        pw_node_id: None,
                     };
                     events.push(Event::CastStartedOrChanged { cast });
                 }
@@ -840,9 +841,12 @@ impl State {
                 let stream_id = cast.stream_id.get();
                 seen.insert(stream_id);
 
+                let pw_node_id = cast.node_id();
                 if state.casts.get(&stream_id).is_none_or(|existing| {
                     // Only these properties can change.
-                    existing.is_active != cast.is_active() || !cast.target.matches(&existing.target)
+                    existing.is_active != cast.is_active()
+                        || !cast.target.matches(&existing.target)
+                        || existing.pw_node_id != pw_node_id
                 }) {
                     let cast = niri_ipc::Cast {
                         session_id: cast.session_id.get(),
@@ -852,6 +856,7 @@ impl State {
                         is_dynamic_target: cast.dynamic_target,
                         is_active: cast.is_active(),
                         pid: None,
+                        pw_node_id,
                     };
                     events.push(Event::CastStartedOrChanged { cast });
                 }
@@ -886,6 +891,7 @@ impl State {
                         is_dynamic_target: false,
                         is_active: true,
                         pid: queue.credentials().map(|creds| creds.pid),
+                        pw_node_id: None,
                     };
                     events.push(Event::CastStartedOrChanged { cast });
                 }

src/screencasting/pw_utils.rs

@@ -819,6 +819,10 @@ impl Cast {
         self.inner.borrow().is_active
     }
 
+    pub fn node_id(&self) -> Option<u32> {
+        self.inner.borrow().node_id
+    }
+
     pub fn ensure_size(&self, size: Size<i32, Physical>) -> anyhow::Result<CastSizeChange> {
         let mut inner = self.inner.borrow_mut();