ScreenCast: Pass PipeWire stream node ID directly

As of commit 5f5ef3de2cdc816dab82cb7eb5d7171bee0ad2c5 in pipewire the
stream creator can find out the node ID of the stream it created.

So instead of using a special purpose entry to the info property box to
let the application discover stream by monitoring added nodes searching
for the given special purpose entry, just pass the node directly.

https://bugzilla.gnome.org/show_bug.cgi?id=784199

src/backends/meta-screen-cast-monitor-stream-src.c

@@ -147,13 +147,9 @@ meta_screen_cast_monitor_stream_src_record_frame (MetaScreenCastStreamSrc *src,
 
 MetaScreenCastMonitorStreamSrc *
 meta_screen_cast_monitor_stream_src_new (MetaScreenCastMonitorStream  *monitor_stream,
-                                         const char                   *stream_id,
                                          GError                      **error)
 {
-  return g_initable_new (META_TYPE_SCREEN_CAST_MONITOR_STREAM_SRC,
+  return g_initable_new (META_TYPE_SCREEN_CAST_MONITOR_STREAM_SRC, NULL, error,
-                         NULL,
-                         error,
-                         "stream-id", stream_id,
                          "stream", monitor_stream,
                          NULL);
 }

src/backends/meta-screen-cast-monitor-stream-src.h

@@ -35,7 +35,6 @@ G_DECLARE_FINAL_TYPE (MetaScreenCastMonitorStreamSrc,
                       MetaScreenCastStreamSrc)
 
 MetaScreenCastMonitorStreamSrc * meta_screen_cast_monitor_stream_src_new (MetaScreenCastMonitorStream *monitor_stream,
-                                                                          const char                  *stream_id,
                                                                           GError                     **error);
 
 #endif /* META_SCREEN_CAST_MONITOR_STREAM_SRC_H */

src/backends/meta-screen-cast-monitor-stream.c

@@ -135,7 +135,6 @@ meta_screen_cast_monitor_stream_new (GDBusConnection     *connection,
 
 static MetaScreenCastStreamSrc *
 meta_screen_cast_monitor_stream_create_src (MetaScreenCastStream  *stream,
-                                            const char            *stream_id,
                                             GError               **error)
 {
   MetaScreenCastMonitorStream *monitor_stream =
@@ -143,7 +142,6 @@ meta_screen_cast_monitor_stream_create_src (MetaScreenCastStream  *stream,
   MetaScreenCastMonitorStreamSrc *monitor_stream_src;
 
   monitor_stream_src = meta_screen_cast_monitor_stream_src_new (monitor_stream,
-                                                                stream_id,
                                                                 error);
   if (!monitor_stream_src)
     return NULL;

src/backends/meta-screen-cast-stream-src.c

@@ -47,11 +47,11 @@ enum
   PROP_0,
 
   PROP_STREAM,
-  PROP_STREAM_ID,
 };
 
 enum
 {
+  READY,
   CLOSED,
 
   N_SIGNALS
@@ -81,7 +81,6 @@ typedef struct _MetaPipeWireSource
 typedef struct _MetaScreenCastStreamSrcPrivate
 {
   MetaScreenCastStream *stream;
-  char *stream_id;
 
   struct pw_core *pipewire_core;
   struct pw_remote *pipewire_remote;
@@ -243,6 +242,9 @@ on_stream_state_changed (void                 *data,
                          const char           *error_message)
 {
   MetaScreenCastStreamSrc *src = data;
+  MetaScreenCastStreamSrcPrivate *priv =
+    meta_screen_cast_stream_src_get_instance_private (src);
+  uint32_t node_id;
 
   switch (state)
     {
@@ -250,9 +252,12 @@ on_stream_state_changed (void                 *data,
       g_warning ("pipewire stream error: %s", error_message);
       meta_screen_cast_stream_src_notify_closed (src);
       break;
+    case PW_STREAM_STATE_CONFIGURE:
+      node_id = pw_stream_get_node_id (priv->pipewire_stream);
+      g_signal_emit (src, signals[READY], 0, (unsigned int) node_id);
+      break;
     case PW_STREAM_STATE_UNCONNECTED:
     case PW_STREAM_STATE_CONNECTING:
-    case PW_STREAM_STATE_CONFIGURE:
     case PW_STREAM_STATE_READY:
     case PW_STREAM_STATE_PAUSED:
       if (meta_screen_cast_stream_src_is_enabled (src))
@@ -585,7 +590,6 @@ meta_screen_cast_stream_src_finalize (GObject *object)
   pw_remote_destroy (priv->pipewire_remote);
   pw_core_destroy (priv->pipewire_core);
   g_source_destroy (&priv->pipewire_source->base);
-  g_clear_pointer (&priv->stream_id, g_free);
 
   G_OBJECT_CLASS (meta_screen_cast_stream_src_parent_class)->finalize (object);
 }
@@ -605,9 +609,6 @@ meta_screen_cast_stream_src_set_property (GObject      *object,
     case PROP_STREAM:
       priv->stream = g_value_get_object (value);
       break;;
-    case PROP_STREAM_ID:
-      priv->stream_id = g_strdup (g_value_get_string (value));
-      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
     }
@@ -628,9 +629,6 @@ meta_screen_cast_stream_src_get_property (GObject    *object,
     case PROP_STREAM:
       g_value_set_object (value, priv->stream);
       break;
-    case PROP_STREAM_ID:
-      g_value_set_string (value, priv->stream_id);
-      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
     }
@@ -659,16 +657,14 @@ meta_screen_cast_stream_src_class_init (MetaScreenCastStreamSrcClass *klass)
                                                         G_PARAM_READWRITE |
                                                         G_PARAM_CONSTRUCT_ONLY |
                                                         G_PARAM_STATIC_STRINGS));
-  g_object_class_install_property (object_class,
-                                   PROP_STREAM_ID,
-                                   g_param_spec_string ("stream-id",
-                                                        "stream-id",
-                                                        "Unique stream ID",
-                                                        NULL,
-                                                        G_PARAM_READWRITE |
-                                                        G_PARAM_CONSTRUCT_ONLY |
-                                                        G_PARAM_STATIC_STRINGS));
 
+  signals[READY] = g_signal_new ("ready",
+                                 G_TYPE_FROM_CLASS (klass),
+                                 G_SIGNAL_RUN_LAST,
+                                 0,
+                                 NULL, NULL, NULL,
+                                 G_TYPE_NONE, 1,
+                                 G_TYPE_UINT);
   signals[CLOSED] = g_signal_new ("closed",
                                   G_TYPE_FROM_CLASS (klass),
                                   G_SIGNAL_RUN_LAST,

src/backends/meta-screen-cast-stream.c

@@ -62,11 +62,9 @@ G_DEFINE_TYPE_WITH_CODE (MetaScreenCastStream,
 
 static MetaScreenCastStreamSrc *
 meta_screen_cast_stream_create_src (MetaScreenCastStream  *stream,
-                                    const char            *stream_id,
                                     GError               **error)
 {
   return META_SCREEN_CAST_STREAM_GET_CLASS (stream)->create_src (stream,
-                                                                 stream_id,
                                                                  error);
 }
 
@@ -81,27 +79,32 @@ on_stream_src_closed (MetaScreenCastStreamSrc *src,
     meta_screen_cast_stream_close (stream);
 }
 
+static void
+on_stream_src_ready (MetaScreenCastStreamSrc *src,
+                     uint32_t                 node_id,
+                     MetaScreenCastStream    *stream)
+{
+  MetaDBusScreenCastStream *skeleton = META_DBUS_SCREEN_CAST_STREAM (stream);
+
+  meta_dbus_screen_cast_stream_emit_pipewire_stream_added (skeleton, node_id);
+}
+
 gboolean
 meta_screen_cast_stream_start (MetaScreenCastStream  *stream,
                                GError               **error)
 {
-  MetaDBusScreenCastStream *skeleton = META_DBUS_SCREEN_CAST_STREAM (stream);
   MetaScreenCastStreamPrivate *priv =
     meta_screen_cast_stream_get_instance_private (stream);
-  g_autofree char *stream_id = NULL;
   MetaScreenCastStreamSrc *src;
-  static unsigned int global_stream_id = 0;
 
-  stream_id = g_strdup_printf ("%u", ++global_stream_id);
+  src = meta_screen_cast_stream_create_src (stream, error);
-  src = meta_screen_cast_stream_create_src (stream, stream_id, error);
   if (!src)
     return FALSE;
 
   priv->src = src;
+  g_signal_connect (src, "ready", G_CALLBACK (on_stream_src_ready), stream);
   g_signal_connect (src, "closed", G_CALLBACK (on_stream_src_closed), stream);
 
-  meta_dbus_screen_cast_stream_emit_pipewire_stream_added (skeleton, stream_id);
-
   return TRUE;
 }
 

src/backends/meta-screen-cast-stream.h

@@ -38,7 +38,6 @@ struct _MetaScreenCastStreamClass
   MetaDBusScreenCastStreamSkeletonClass parent_class;
 
   MetaScreenCastStreamSrc * (* create_src) (MetaScreenCastStream *stream,
-                                            const char           *stream_id,
                                             GError              **error);
 };
 

src/org.gnome.Mutter.ScreenCast.xml

@@ -99,7 +99,7 @@
     -->
     <signal name="PipeWireStreamAdded">
       <annotation name="org.gtk.GDBus.C.Name" value="pipewire-stream-added"/>
-      <arg name="stream_id" type="s" direction="out" />
+      <arg name="node_id" type="u" direction="out" />
     </signal>
 
   </interface>