Merge pull request #1319 from jetic83/master

Solves issue #1318 for transparent TiledImages

src/tiledimage.js

@@ -311,6 +311,10 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
             this._updateViewport();
             this._midDraw = false;
         }
+        // Images with opacity 0 should not need to be drawn in future. this._needsDraw = false is set in this._updateViewport() for other images.
+        else {
+            this._needsDraw = false;
+        }
     },
 
     /**