fixes #110: properly query local tile sources

@@ -12,6 +12,8 @@
 #import "RMTileSource.h"
 #import "RMTileImage.h"
 #import "RMTileCache.h"
+#import "RMMBTilesSource.h"
+#import "RMDBMapSource.h"
 
 @implementation RMMapTiledLayerView
 {
@@ -118,6 +120,16 @@
 
         if (zoom >= _tileSource.minZoom && zoom <= _tileSource.maxZoom)
         {
+            if ([_tileSource isKindOfClass:[RMMBTilesSource class]] || [_tileSource isKindOfClass:[RMDBMapSource class]])
+            {
+                // for local tiles, query the source directly since trivial blocking
+                //
+                tileImage = [_tileSource imageForTile:RMTileMake(x, y, zoom) inCache:[_mapView tileCache]];
+            }
+            else
+            {
+                // for non-local tiles, consult cache directly first, else fetch asynchronously
+                //
                 tileImage = [[_mapView tileCache] cachedImage:RMTileMake(x, y, zoom) withCacheKey:[_tileSource uniqueTilecacheKey]];
 
                 if ( ! tileImage)
@@ -134,6 +146,7 @@
                     });
                 }
             }
+        }
 
         if ( ! tileImage)
         {