src/main/java/org/apache/log4j/chainsaw/icons/LevelIconFactory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.chainsaw.icons;

import java.awt.Image;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import javax.swing.ImageIcon;
import javax.swing.UIManager;
import javax.swing.plaf.metal.MetalLookAndFeel;

/**
 */
public class LevelIconFactory {
  private static final LevelIconFactory instance = new LevelIconFactory();
  private final Map<String, javax.swing.Icon> iconMap = new HashMap<>();

  private LevelIconFactory() {
    //reuse ERROR icon for FATAL level
    String[] iconFileNames =
      new String[] { "Warn.gif", "Inform.gif", "Error.gif" , "Error.gif"};
    String[] iconLabels = new String[] { "WARN", "INFO", "ERROR", "FATAL" };

    for (int i = 0; i < iconLabels.length; i++) {
      URL resourceURL = UIManager.getLookAndFeel().getClass().getResource(
          "icons/" + iconFileNames[i]);
      if(resourceURL == null) {
        resourceURL = MetalLookAndFeel.class.getResource(
          "icons/" + iconFileNames[i]);
      }
      if(resourceURL == null) {
        throw new IllegalStateException("Was unable to locate an L&F icon using either the current L&F or the cross platform L&F.");
      }
      
      final ImageIcon icon =
        new ImageIcon(resourceURL);
      double scalex = .5;
      double scaley = .5;
      final int newWidth = (int) (scalex * icon.getIconWidth());
      final int newHeight = (int) (scaley * icon.getIconHeight());
      Image iconImage =
        icon.getImage().getScaledInstance(
          newWidth, newHeight, Image.SCALE_SMOOTH);
      iconMap.put(iconLabels[i], new ImageIcon(iconImage));
    }
    //reuse DEBUG icon for TRACE level
    iconMap.put("TRACE", ChainsawIcons.ICON_DEBUG);
    iconMap.put("DEBUG", ChainsawIcons.ICON_DEBUG);
  }

  public static final LevelIconFactory getInstance() {
    return instance;
  }

  public Map<String, javax.swing.Icon> getLevelToIconMap() {
    return iconMap;
  }
}