mi-info: prepare for async discovery

The async api usage is not yet activated due to some uncertanty in the api use.

mediainfo/src/mi-info.vala

@@ -252,6 +252,7 @@ public class MediaInfo.Info : VPaned
     // set up the gstreamer components
     try {
       dc = new Discoverer ((ClockTime)(Gst.SECOND * 10));
+      dc.discovered.connect (on_uri_discovered);
     } catch (Error e) {
       debug ("Failed to create the discoverer: %s: %s", e.domain.to_string (), e.message);
     }
@@ -276,15 +277,14 @@ public class MediaInfo.Info : VPaned
   {
     bool res = true;
 
+    if (uri != null) {
+      File file = File.new_for_uri(uri);
+
       // stop previous playback
       pb.set_state (State.READY);
       album_art = null;
       drawing_area.queue_draw();
 
-    if (uri != null) {
-      DiscovererInfo info;
-      File file = File.new_for_uri(uri);
-
       try {
         FileInfo finfo = file.query_info ("standard::*", FileQueryInfoFlags.NONE, null);
         mime_type.set_text (finfo.get_attribute_string (FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE));
@@ -293,7 +293,30 @@ public class MediaInfo.Info : VPaned
         debug ("Failed to query file info from %s: %s: %s", uri, e.domain.to_string (), e.message);
       }
 
+      if (true) {
+        /* sync API */
         try {
+          on_uri_discovered (dc.discover_uri (uri), null);
+        } catch (Error e) {
+          debug ("Failed to extract metadata from %s: %s: %s", uri, e.domain.to_string (), e.message);
+        }
+      } else {
+        /* async API */
+        stdout.printf ("Stop current discover\n");
+        dc.stop();
+        stdout.printf ("Enqueue uri\n");
+        dc.discover_uri_async (uri);
+        stdout.printf ("Start discover\n");
+        dc.start();
+        stdout.printf ("Started discover\n");
+      }
+    }
+    return (res);
+  }
+
+  private void on_uri_discovered (DiscovererInfo info, Error e)
+  {
+    string uri = info.get_uri();
     GLib.List<DiscovererStreamInfo> l;
     DiscovererStreamInfo sinfo;
     //DiscovererVideoInfo vinfo;
@@ -308,7 +331,14 @@ public class MediaInfo.Info : VPaned
     Caps caps;
     Structure s;
 
-        info = dc.discover_uri (uri);
+    stdout.printf ("uri has been discovered\n");
+
+    if (e != null) {
+      debug ("Failed to extract metadata from %s: %s: %s", uri, e.domain.to_string (), e.message);
+    }
+    if (info == null) {
+      return;
+    }
 
     ClockTime dur = info.get_duration ();
     str = "%u:%02u:%02u.%09u".printf (
@@ -338,6 +368,7 @@ public class MediaInfo.Info : VPaned
     }
     */
     sinfo = info.get_stream_info ();
+    if (sinfo != null) {
       caps = sinfo.get_caps ();
       wikilink = wikilinks[caps.get_structure(0).get_name()];
       str = pb_utils_get_codec_description (caps);
@@ -346,6 +377,7 @@ public class MediaInfo.Info : VPaned
         container_name.set_markup ("<a href=\"http://en.wikipedia.org/wiki/%s\">%s</a>".printf (wikilink, str));
       } else {
         container_name.set_text (str);
+      }
     }
 
 		  // reset notebooks
@@ -594,19 +626,10 @@ public class MediaInfo.Info : VPaned
 
     //l = info.get_container_streams ();
 
-      } catch (Error e) {
-        debug ("Failed to extract metadata from %s: %s: %s", uri, e.domain.to_string (), e.message);
-      }
-
     // play file
     cur_video_stream = cur_audio_stream = 0;
     ((GLib.Object)pb).set_property ("uri", uri);
     pb.set_state (State.PLAYING);
-
-      res = true;
-    }
-
-    return (res);
   }
 
   // signal handlers