[mutter] screen-cast-session: Add window-id support

[Jonas Ådahl <jadahl src gnome org>]

commit c786b6c13cf9cb1bb9d7f7d2ca0ead0bf28a5fcd
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Mon Oct 15 12:08:29 2018 +0200

    screen-cast-session: Add window-id support
    
    Use the "window-id" property to select the window to cast using
    RecordWindow.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/306

 src/backends/meta-screen-cast-session.c | 19 ++++++++++++++++++-
 src/org.gnome.Mutter.ScreenCast.xml     |  5 ++++-
 2 files changed, 22 insertions(+), 2 deletions(-)
---
diff --git a/src/backends/meta-screen-cast-session.c b/src/backends/meta-screen-cast-session.c
index 3ee02c552..d0f5a79d9 100644
--- a/src/backends/meta-screen-cast-session.c
+++ b/src/backends/meta-screen-cast-session.c
@@ -340,6 +340,7 @@ handle_record_window (MetaDBusScreenCastSession *skeleton,
   MetaWindow *window;
   GError *error = NULL;
   MetaDisplay *display;
+  GVariant *window_id_variant = NULL;
   MetaScreenCastWindowStream *window_stream;
   MetaScreenCastStream *stream;
   char *stream_path;
@@ -352,8 +353,24 @@ handle_record_window (MetaDBusScreenCastSession *skeleton,
       return TRUE;
     }
 
+  if (properties_variant)
+    window_id_variant = g_variant_lookup_value (properties_variant,
+                                                "window-id",
+                                                G_VARIANT_TYPE ("t"));
+
   display = meta_get_display ();
-  window = meta_display_get_focus_window (display);
+  if (window_id_variant)
+    {
+      uint64_t window_id;
+
+      g_variant_get (window_id_variant, "t", &window_id);
+      window = meta_display_get_window_from_id (display, window_id);
+    }
+  else
+    {
+      window = meta_display_get_focus_window (display);
+    }
+
   if (!window)
     {
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
diff --git a/src/org.gnome.Mutter.ScreenCast.xml b/src/org.gnome.Mutter.ScreenCast.xml
index 61345564b..3cd02b6cb 100644
--- a/src/org.gnome.Mutter.ScreenCast.xml
+++ b/src/org.gnome.Mutter.ScreenCast.xml
@@ -86,7 +86,10 @@
 
        Record a single window.
 
-       Available @properties include: (none)
+       Available @properties include:
+
+       * "window-id" (t): Id of the window to record.
+
     -->
     <method name="RecordWindow">
       <arg name="properties" type="a{sv}" direction="in" />