Adds overzoom support to mbtile and NPE fixes

vtm-android/src/org/oscim/android/tiling/source/mbtiles/MBTilesBitmapTileDataSource.java

@@ -108,21 +108,22 @@ public void query(MapTile tile, ITileDataSink sink) {
         QueryResult res = QueryResult.FAILED;
         try {
             byte[] bytes = readTile(tile.tileX, tile.tileY, tile.zoomLevel);
-
-            if (mTransparentColor != null || mAlpha != null) {
-                android.graphics.Bitmap androidBitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
-                if (mTransparentColor != null)
-                    androidBitmap = processTransparentColor(androidBitmap, mTransparentColor);
-                if (mAlpha != null)
-                    androidBitmap = processAlpha(androidBitmap, mAlpha);
-                ByteArrayOutputStream bos = new ByteArrayOutputStream();
-                androidBitmap.compress(android.graphics.Bitmap.CompressFormat.PNG, 100, bos);
-                bytes = bos.toByteArray();
-            }
-
-            Bitmap bitmap = CanvasAdapter.decodeBitmap(new ByteArrayInputStream(bytes));
-            sink.setTileImage(bitmap);
-            res = QueryResult.SUCCESS;
+            if (bytes != null) {
+                if (mTransparentColor != null || mAlpha != null) {
+                    android.graphics.Bitmap androidBitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
+                    if (mTransparentColor != null)
+                        androidBitmap = processTransparentColor(androidBitmap, mTransparentColor);
+                    if (mAlpha != null)
+                        androidBitmap = processAlpha(androidBitmap, mAlpha);
+                    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+                    androidBitmap.compress(android.graphics.Bitmap.CompressFormat.PNG, 100, bos);
+                    bytes = bos.toByteArray();
+                }
+
+                Bitmap bitmap = CanvasAdapter.decodeBitmap(new ByteArrayInputStream(bytes));
+                sink.setTileImage(bitmap);
+                res = QueryResult.SUCCESS;
+	    }
         } catch (Throwable t) {
             log.severe(t.toString());
         } finally {

vtm-android/src/org/oscim/android/tiling/source/mbtiles/MBTilesBitmapTileSource.java

@@ -40,4 +40,30 @@ public MBTilesBitmapTileSource(String path) {
     public MBTilesBitmapTileSource(String path, Integer alpha, Integer transparentColor) {
         super(new MBTilesBitmapTileDataSource(path, alpha, transparentColor));
     }
+
+    /**
+     * Create a tile source for MBTiles raster databases.
+     *
+     * @param path             the path to the MBTiles database.
+     * @param overZoom         allow over zooming to this level.
+     */
+    public MBTilesBitmapTileSource(String path, int overZoom) {
+        this(path, null, null, overZoom);
+    }
+
+    /**
+     * Create a tile source for MBTiles raster databases.
+     *
+     * @param path             the path to the MBTiles database.
+     * @param alpha            an optional alpha value [0-255] to make the tiles transparent.
+     * @param transparentColor an optional color that will be made transparent in the bitmap.
+     * @param overZoom         allow over zooming to this level.
+     */
+    public MBTilesBitmapTileSource(String path, Integer alpha, Integer transparentColor, int overZoom) {
+        super(new MBTilesBitmapTileDataSource(path, alpha, transparentColor));
+        MBTilesTileDataSource ds = getDataSource();
+        mZoomMin = ds.getMinZoom();
+        mZoomMax = ds.getMaxZoom();
+        mOverZoom = overZoom;
+    }
 }

vtm/src/org/oscim/layers/tile/bitmap/BitmapTileLoader.java

@@ -55,7 +55,7 @@ protected boolean loadTile(MapTile tile) {
 
     @Override
     public void setTileImage(Bitmap bitmap) {
-        if (isCanceled() || !mTile.state(LOADING)) {
+        if (mTile == null || isCanceled() || !mTile.state(LOADING)) {
             bitmap.recycle();
             return;
         }