[cheese] webcam: fix broken xoverlay management

[Filippo Argiolas <fargiolas src gnome org>]

commit 3d7565f536d0d3014e65e4d9f6d97d4ef0e6ee09
Author: Filippo Argiolas <filippo argiolas gmail com>
Date:   Sat Jul 4 09:16:43 2009 +0200

    webcam: fix broken xoverlay management
    
    For some reason this went unnoticed for a long time. We were calling
    set_x_overlay right after setting PLAYING state (with no warranty that
    the state change succeeded nor that an overlay was really there). The
    only right way to do this is to wait for prepare-xwindow-id message. It
    worked until now just because we've been extremely lucky.

 src/cheese-webcam.c |   27 ++++++++++++++++++---------
 1 files changed, 18 insertions(+), 9 deletions(-)
---
diff --git a/src/cheese-webcam.c b/src/cheese-webcam.c
index 3a75177..caada48 100644
--- a/src/cheese-webcam.c
+++ b/src/cheese-webcam.c
@@ -153,13 +153,19 @@ cheese_webcam_error_quark (void)
   return g_quark_from_static_string ("cheese-webcam-error-quark");
 }
 
-static void
-cheese_webcam_set_x_overlay (CheeseWebcam *webcam)
+static GstBusSyncReply
+cheese_webcam_bus_sync_handler (GstBus * bus, GstMessage * message, CheeseWebcam *webcam)
 {
   CheeseWebcamPrivate *priv = CHEESE_WEBCAM_GET_PRIVATE (webcam);
+  GstXOverlay *overlay;
 
-  GstXOverlay *overlay = GST_X_OVERLAY (gst_bin_get_by_interface (GST_BIN (priv->pipeline),
-                                                                  GST_TYPE_X_OVERLAY));
+  if (GST_MESSAGE_TYPE (message) != GST_MESSAGE_ELEMENT)
+    return GST_BUS_PASS;
+
+  if (!gst_structure_has_name (message->structure, "prepare-xwindow-id"))
+    return GST_BUS_PASS;
+
+  overlay = GST_X_OVERLAY (GST_MESSAGE_SRC (message));
 
   if (g_object_class_find_property (G_OBJECT_GET_CLASS (overlay),
                                     "force-aspect-ratio"))
@@ -167,6 +173,10 @@ cheese_webcam_set_x_overlay (CheeseWebcam *webcam)
 
   gst_x_overlay_set_xwindow_id (overlay,
                                 GDK_WINDOW_XWINDOW (gtk_widget_get_window (priv->video_window)));
+
+  gst_message_unref (message);
+
+  return GST_BUS_DROP;
 }
 
 static void
@@ -198,6 +208,7 @@ cheese_webcam_expose_cb (GtkWidget *widget, GdkEventExpose *event, CheeseWebcam
                                                                   GST_TYPE_X_OVERLAY));
 
   gst_x_overlay_expose (overlay);
+
   return FALSE;
 }
 
@@ -1255,11 +1266,7 @@ cheese_webcam_play (CheeseWebcam *webcam)
 {
   CheeseWebcamPrivate *priv = CHEESE_WEBCAM_GET_PRIVATE (webcam);
 
-  GstStateChangeReturn ret;
-
-  ret = gst_element_set_state (priv->pipeline, GST_STATE_PLAYING);
-  cheese_webcam_set_x_overlay (webcam);
-
+  gst_element_set_state (priv->pipeline, GST_STATE_PLAYING);
   priv->pipeline_is_playing = TRUE;
 }
 
@@ -1655,6 +1662,8 @@ cheese_webcam_setup (CheeseWebcam *webcam, char *hal_dev_udi, GError **error)
   g_signal_connect (G_OBJECT (priv->bus), "message",
                     G_CALLBACK (cheese_webcam_bus_message_cb), webcam);
 
+  gst_bus_set_sync_handler (priv->bus, (GstBusSyncHandler) cheese_webcam_bus_sync_handler, webcam);
+
   if (!ok)
     g_error ("Unable link pipeline for photo");
 }