Add ThemeCallbackAdapter class (#1253)

Author: devemux86

vtm/src/org/oscim/theme/ThemeCallbackAdapter.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2016-2019 devemux86
+ *
+ * This program is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.oscim.theme;
+
+import org.oscim.backend.canvas.Bitmap;
+import org.oscim.core.MapElement;
+import org.oscim.theme.styles.RenderStyle;
+
+/**
+ * Callback methods for render theme.
+ */
+public abstract class ThemeCallbackAdapter implements ThemeCallback {
+    /**
+     * @return the resource {@link Bitmap}
+     */
+    @Override
+    public Bitmap getBitmap(Bitmap bitmap) {
+        return bitmap;
+    }
+
+    /**
+     * @return the color-int
+     */
+    @Override
+    public int getColor(RenderStyle origin, int color) {
+        return color;
+    }
+
+    /**
+     * @return the color-int
+     */
+    @Override
+    public int getColor(String[] keys, String[] values, int color) {
+        return color;
+    }
+
+    /**
+     * @return the text
+     */
+    @Override
+    public String getText(MapElement element, String text) {
+        return text;
+    }
+}