Dispatch a SIZE_KNOWN event when we know our media's size.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@4461 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/as/com/threerings/util/MediaContainer.as

@@ -48,6 +48,9 @@ import com.threerings.media.image.ImageUtil;
  */
 public class MediaContainer extends Box
 {
+    /** An event we dispatch when our size is known. */
+    public static const SIZE_KNOWN :String = "mediaSizeKnown";
+
     /** A log instance that can be shared by sprites. */
     protected static const log :Log = Log.getLog(MediaContainer);
 
@@ -482,6 +485,12 @@ public class MediaContainer extends Box
         if (_w != ww || _h != hh) {
             _w = ww;
             _h = hh;
+            // TODO: I think that I'll want to create a subclass of the
+            // basic media container which does things that are usefulish
+            // but separate from MsoySprite. SIZE_KNOWN is one of those
+            // things that should probably be moved. Maybe BaseMediaContainer
+            // and MediaContainer? FancyMediaContainer?
+            dispatchEvent(new Event(SIZE_KNOWN));
             contentDimensionsUpdated();
         }
     }