docs: public void protectDisplayedTilesForCache(final Canvas pCanvas, final Projection pProjection) {
  		if (!setViewPort(pCanvas, pProjection)) {
  			return;
  		}
  		TileSystem.getTileFromMercator(mViewPort, TileSystem.getTileSize(mProjection.getZoomLevel()), mProtectedTiles);
  		final int tileZoomLevel = TileSystem.getInputTileZoomLevel(mProjection.getZoomLevel());
  		mTileProvider.getTileCache().getMapTileArea().set(tileZoomLevel, mProtectedTiles);
  		mTileProvider.getTileCache().maintenance();
  	}