[cheese] Show an error message if the camera state is NULL

[David King <davidk src gnome org>]

commit 202e73abf80ad737658a9e7a20f5502a406eb64b
Author: David King <amigadave amigadave com>
Date:   Wed Jun 26 22:01:12 2013 +0100

    Show an error message if the camera state is NULL
    
    If there is a GST_MESSAGE_ERROR, stop the stream and emit
    ::state-flags-changed on the CheeseCamera. Handle the state change in
    CheeseWindow by showing a generic error message. This message can easily
    occur if the video device is busy, such as when another application is
    using the webcam.
    
    Fixes bug 703123.

 libcheese/cheese-camera.c |    7 +++++--
 src/cheese-main.vala      |    7 ++++---
 src/cheese-window.vala    |    9 +++++++++
 3 files changed, 18 insertions(+), 5 deletions(-)
---
diff --git a/libcheese/cheese-camera.c b/libcheese/cheese-camera.c
index dbad241..a625359 100644
--- a/libcheese/cheese-camera.c
+++ b/libcheese/cheese-camera.c
@@ -184,7 +184,7 @@ cheese_camera_photo_data (CheeseCamera *camera, GstSample *sample)
  * @camera: the #CheeseCamera
  *
  * Process messages create by the @camera on the @bus. Emit
- * ::state-flags-changes if the state of the camera has changed.
+ * ::state-flags-changed if the state of the camera has changed.
  */
 static void
 cheese_camera_bus_message_cb (GstBus *bus, GstMessage *message, CheeseCamera *camera)
@@ -216,12 +216,15 @@ cheese_camera_bus_message_cb (GstBus *bus, GstMessage *message, CheeseCamera *ca
       gst_message_parse_error (message, &err, &debug);
 
       if (err && err->message) {
-        g_warning ("%s\n", err->message);
+        g_warning ("%s: %s\n", err->message, debug);
         g_error_free (err);
       } else {
         g_warning ("Unparsable GST_MESSAGE_ERROR message.\n");
       }
 
+      cheese_camera_stop (camera);
+      g_signal_emit (camera, camera_signals[STATE_FLAGS_CHANGED], 0,
+                     GST_STATE_NULL);
       g_free (debug);
       break;
     }
diff --git a/src/cheese-main.vala b/src/cheese-main.vala
index 16ea591..51fba55 100644
--- a/src/cheese-main.vala
+++ b/src/cheese-main.vala
@@ -254,10 +254,8 @@ public class Cheese.Main : Gtk.Application
         {
             video_preview.hide ();
             warning ("Error: %s\n", err.message);
-            //error_layer.text = err.message;
-            //error_layer.show ();
+            main_window.show_error (err.message);
 
-            //toggle_camera_actions_sensitivities (false);
             return;
         }
 
@@ -332,6 +330,9 @@ public class Cheese.Main : Gtk.Application
             case Gst.State.PLAYING:
                 main_window.camera_state_change_playing ();
                 break;
+            case Gst.State.NULL:
+                main_window.camera_state_change_null ();
+                break;
             default:
                 break;
         }
diff --git a/src/cheese-window.vala b/src/cheese-window.vala
index 584eb6d..ce4596f 100644
--- a/src/cheese-window.vala
+++ b/src/cheese-window.vala
@@ -1282,6 +1282,15 @@ public class Cheese.MainWindow : Gtk.ApplicationWindow
         }
     }
 
+    /**
+     * Report an error as the camerabin switched to the NULL state.
+     */
+    public void camera_state_change_null ()
+    {
+        show_error (_("There was an error playing video from the webcam"));
+        toggle_camera_actions_sensitivities (false);
+    }
+
   /**
    * Set wide mode active when started from the command line (and do not change
    * the GSetting).