added Theme interface

xchart/src/main/java/com/xeiam/xchart/style/theme/XChartTheme.java

+/**
+ * Copyright (C) 2013 Xeiam LLC http://xeiam.com
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is furnished to do
+ * so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.xeiam.xchart.style.theme;
+
+import java.awt.Color;
+
+import com.xeiam.xchart.style.ChartColor;
+
+/**
+ * @author timmolter
+ */
+public class XChartTheme implements Theme {
+
+  @Override
+  public Color getChartBackgroundColor() {
+
+    return ChartColor.getAWTColor(ChartColor.GREY);
+  }
+
+  @Override
+  public Color getChartBordersColor() {
+
+    return ChartColor.getAWTColor(ChartColor.DARK_GREY);
+  }
+
+  @Override
+  public Color getChartFontColor() {
+
+    return ChartColor.getAWTColor(ChartColor.BLACK);
+  }
+
+}