screen-cast-session: Add 'disable-animations' property

Allow screen casters (e.g. VNC remote desktop services) to ask for
animations to be inhibited, in order to lower the number of frames sent
over the network.

Currently only sets a field on the screen cast session object. Later
it'll be exposed via the remote access handle and via D-Bus by
gnome-shell.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/838

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

@@ -48,6 +48,8 @@ struct _MetaScreenCastSession
   GList *streams;
 
   MetaScreenCastSessionHandle *handle;
+
+  gboolean disable_animations;
 };
 
 static void
@@ -167,6 +169,13 @@ meta_screen_cast_session_get_screen_cast (MetaScreenCastSession *session)
   return session->screen_cast;
 }
 
+void
+meta_screen_cast_session_set_disable_animations (MetaScreenCastSession *session,
+                                                 gboolean               disable_animations)
+{
+  session->disable_animations = disable_animations;
+}
+
 char *
 meta_screen_cast_session_get_object_path (MetaScreenCastSession *session)
 {

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

@@ -64,4 +64,7 @@ MetaScreenCastStream * meta_screen_cast_session_get_stream (MetaScreenCastSessio
 
 MetaScreenCast * meta_screen_cast_session_get_screen_cast (MetaScreenCastSession *session);
 
+void meta_screen_cast_session_set_disable_animations (MetaScreenCastSession *session,
+                                                      gboolean               disable_animations);
+
 #endif /* META_SCREEN_CAST_SESSION_H */

src/backends/meta-screen-cast.c

@@ -32,7 +32,7 @@
 
 #define META_SCREEN_CAST_DBUS_SERVICE "org.gnome.Mutter.ScreenCast"
 #define META_SCREEN_CAST_DBUS_PATH "/org/gnome/Mutter/ScreenCast"
-#define META_SCREEN_CAST_API_VERSION 2
+#define META_SCREEN_CAST_API_VERSION 3
 
 struct _MetaScreenCast
 {
@@ -116,6 +116,7 @@ handle_create_session (MetaDBusScreenCast    *skeleton,
   const char *session_path;
   const char *client_dbus_name;
   char *remote_desktop_session_id = NULL;
+  gboolean disable_animations;
   MetaScreenCastSessionType session_type;
 
   g_variant_lookup (properties, "remote-desktop-session-id", "s",
@@ -160,6 +161,13 @@ handle_create_session (MetaDBusScreenCast    *skeleton,
         }
     }
 
+  if (g_variant_lookup (properties, "disable-animations", "b",
+                        &disable_animations))
+    {
+      meta_screen_cast_session_set_disable_animations (session,
+                                                       disable_animations);
+    }
+
   client_dbus_name = g_dbus_method_invocation_get_sender (invocation);
   meta_dbus_session_watcher_watch_session (screen_cast->session_watcher,
                                            client_dbus_name,

src/org.gnome.Mutter.ScreenCast.xml

@@ -22,6 +22,10 @@
 					   Remote desktop driven screen casts
 					   are started and stopped by the remote
 					   desktop session.
+	* "disable-animations" (b): Set to "true" if the screen cast application
+				    would prefer animations to be globally
+				    disabled, while the session is running. Default
+				    is "false". Available since version 3.
     -->
     <method name="CreateSession">
       <arg name="properties" type="a{sv}" direction="in" />