title: OpenLayers: How to detect the map view is completely loaded?
body: <p>I'm implementing map exporting functionality using OpenLayers 3.</p>
  
  <p>But there is one problem: one cannot determine whether the map view is completely loaded or a few tiles is missing yet.</p>
  
  <p>It seems there is no such API or event. The close one is tileloadstart - tileloadend pair. But OpenLayers loads tiles asynchronously, and before the tile is actually loading the tileloadstart is not fired - that is, a tile that is queued in the tile queue does not fire the event before actually loading.</p>
  
  <p>Hot can I detect the map view is completely loaded?</p>