title: OSMDroid PathOverlay drawing is corrupted at high zoom levels
body: <p>I'm using OSMdroid to implement a mapping application.</p>
  
  <p>I have implemented a custom MapTileProvider that uses a tile source that allows zoom levels up to 22.</p>
  
  <p>The default MAPNIK provider only allows zooms to level 18.</p>
  
  <p>The problem is that any PathOverlay instances draw perfectly until zoom level 19, but then
  are not drawn properly at zoom level 20-22. it looks like someone's rubbed out the path with an eraser over 90% of the path length (see screenshots below).</p>
  
  <p>I've stepped through the draw() method of PathOverlay and exerything <em>seems</em> to be calculating correctly (the intermediate points appear correct for ZoomLevel 22, and then the XY projections are dividing by 22-ZoomLevel to get current screen coordinates). </p>
  
  <p>Can anyone provide some insight as to what the problem is, and how to resolve it?</p>
  
  <p>The same thing happens if I invoke the MapView using Cloudmade small tiles, which allows zooms up until level 20 and is a 'built-in' osmDroid tile provider class.</p>
  
  <pre><code>    //mMapTileProvider = new HighResMapTileProvider(this);
      mMapTileProvider = new MapTileProviderBasic(this,TileSourceFactory.CLOUDMADESMALLTILES);
      mMapView = new MapView(this, 256, mResourceProxy,mMapTileProvider);
  </code></pre>
  
  <p>So the problem does not appear to be with the tile source or provider but with the canvas drawing method. Any ideas on how to resolve this?</p>
  
  <p>At zoomLevel 19 I can see my paths nicely:
  <img src="https://i.stack.imgur.com/iNOx7.png" alt="ZoomLevel 19"></p>
  
  <p>But here is that same path at the next zoom level:
  <img src="https://i.stack.imgur.com/qKnIG.png" alt="enter image description here"></p>