camerabin: add viewfinder-filter property

Adds a new property called viewfinder-filter to camerabin.
This property is used to add a filter to process the video
flow right before the viewfinder sink.

Also updates test to check property exists.

gst/camerabin/gstcamerabin-enum.h

@@ -57,7 +57,8 @@ enum
   ARG_APERTURE,
   ARG_EXPOSURE,
   ARG_VIDEO_SOURCE_FILTER,
-  ARG_IMAGE_CAPTURE_SUPPORTED_CAPS
+  ARG_IMAGE_CAPTURE_SUPPORTED_CAPS,
+  ARG_VIEWFINDER_FILTER
 };
 
 /**

gst/camerabin/gstcamerabin.c

@@ -690,6 +690,14 @@ camerabin_create_view_elements (GstCameraBin * camera)
       goto error;
     }
   }
+
+  if (camera->app_viewfinder_filter) {
+    if (!gst_camerabin_add_element (GST_BIN (camera),
+            camera->app_viewfinder_filter)) {
+      goto error;
+    }
+  }
+
   /* Add application set or default video sink element */
   if (!(camera->view_sink = gst_camerabin_setup_default_element (cbin,
               camera->app_vf_sink, "autovideosink", DEFAULT_VIDEOSINK))) {
@@ -900,6 +908,11 @@ camerabin_dispose_elements (GstCameraBin * camera)
     camera->app_video_filter = NULL;
   }
 
+  if (camera->app_viewfinder_filter) {
+    gst_object_unref (camera->app_viewfinder_filter);
+    camera->app_viewfinder_filter = NULL;
+  }
+
   /* Free caps */
   gst_caps_replace (&camera->image_capture_caps, NULL);
   gst_caps_replace (&camera->view_finder_caps, NULL);
@@ -2711,6 +2724,21 @@ gst_camerabin_class_init (GstCameraBinClass * klass)
           "Caps defining the preview image format",
           GST_TYPE_CAPS, G_PARAM_READWRITE));
 
+  /**
+   * GstCameraBin:viewfinder-filter:
+   * Set up viewfinder filter element, all frames going to viewfinder sink
+   * element will be processed by this element.
+   * Applications can use this to overlay text/images in the screen, or
+   * plug facetracking algorithms, for example.
+   * This property can only be set while #GstCameraBin is in NULL state.
+   * The ownership of the element will be taken by #GstCameraBin.
+   */
+
+  g_object_class_install_property (gobject_class, ARG_VIEWFINDER_FILTER,
+      g_param_spec_object ("viewfinder-filter", "viewfinder filter element",
+          "viewfinder filter GStreamer element",
+          GST_TYPE_ELEMENT, G_PARAM_READWRITE));
+
   /**
    * GstCameraBin::capture-start:
    * @camera: the camera bin element
@@ -2905,6 +2933,7 @@ gst_camerabin_init (GstCameraBin * camera, GstCameraBinClass * gclass)
   camera->view_sink = NULL;
 
   camera->app_vf_sink = NULL;
+  camera->app_viewfinder_filter = NULL;
 
   /* source elements */
   camera->src_vid_src = NULL;
@@ -3152,6 +3181,17 @@ gst_camerabin_set_property (GObject * object, guint prop_id,
       }
       break;
     }
+    case ARG_VIEWFINDER_FILTER:
+      if (GST_STATE (camera) != GST_STATE_NULL) {
+        GST_ELEMENT_ERROR (camera, CORE, FAILED,
+            ("camerabin must be in NULL state when setting the viewfinder filter element"),
+            (NULL));
+      } else {
+        if (camera->app_viewfinder_filter)
+          gst_object_unref (camera->app_viewfinder_filter);
+        camera->app_viewfinder_filter = g_value_dup_object (value);
+      }
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -3244,6 +3284,9 @@ gst_camerabin_get_property (GObject * object, guint prop_id,
       else if (camera->mode == MODE_VIDEO)
         gst_value_set_caps (value, camera->video_preview_caps);
       break;
+    case ARG_VIEWFINDER_FILTER:
+      g_value_set_object (value, camera->app_viewfinder_filter);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;

gst/camerabin/gstcamerabin.h

@@ -138,6 +138,7 @@ struct _GstCameraBin
   GstElement *app_vid_src;
   GstElement *app_vf_sink;
   GstElement *app_video_filter;
+  GstElement *app_viewfinder_filter;
 
   /* Night mode handling */
   gboolean night_mode;

tests/check/elements/camerabin.c

@@ -122,7 +122,7 @@ static void
 setup_camerabin_elements (GstElement * camera)
 {
   GstElement *vfsink, *audiosrc, *videosrc, *audioenc, *videoenc, *imageenc,
-      *videomux;
+      *videomux, *viewfinder_filter;
   GstCaps *audiocaps, *videocaps;
 
   /* Use fakesink for view finder */
@@ -143,12 +143,14 @@ setup_camerabin_elements (GstElement * camera)
   gst_caps_unref (videocaps);
   videomux = gst_element_factory_make ("avimux", NULL);
   imageenc = gst_element_factory_make ("jpegenc", NULL);
+  viewfinder_filter = gst_element_factory_make ("identity", NULL);
 
   if (vfsink && audiosrc && videosrc && audioenc && videoenc && videomux
-      && imageenc) {
+      && imageenc && viewfinder_filter) {
     g_object_set (camera, "viewfinder-sink", vfsink, "audio-source", audiosrc,
         "video-source", videosrc, "audio-encoder", audioenc, "video-encoder",
-        videoenc, "image-encoder", imageenc, "video-muxer", videomux, NULL);
+        videoenc, "image-encoder", imageenc, "video-muxer", videomux,
+        "viewfinder-filter", viewfinder_filter, NULL);
   } else {
     GST_WARNING ("error setting up test plugins");
   }