Single instance status bar : Status Bar « Swing Components « Java

1. Java
2. Swing Components
3. Status Bar

Single instance status bar

   
/*
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY
 * DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT OF OR
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 * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS
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 * 
 * You acknowledge that this software is not designed, licensed or
 * intended for use in the design, construction, operation or
 * maintenance of any nuclear facility.
 */


import java.awt.*;

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.*;

/**
 * Single instance status bar.
 * <p>
 * This class is also a MouseListener which listens to MOUSE_ENTERED
 * and MOUSE_EXITED events from Action derived components so that
 * the value of the Action.LONG_DESCRIPTION key is sent as a message
 * to the status bar. 
 * <p>
 * To enable this behavior, add the StatusBar
 * instance as a MouseListener to the component that was created from 
 * an Action.
 *
 * @version 1.6 01/15/03
 * @author  Mark Davidson
 */
public class StatusBar extends JPanel implements MouseListener {
  
    private JLabel label;
    private Dimension preferredSize;

    private static StatusBar INSTANCE;
  
    public StatusBar()  {
  this.setLayout(new FlowLayout(FlowLayout.LEFT));
  this.setBorder(BorderFactory.createEtchedBorder());
                               
  // Set a large blank label to set the preferred size.
  label = new JLabel("                                                                                        ");
  preferredSize = new Dimension(getWidth(label.getText()), 2 * getFontHeight());
      
  this.add(label);
    }


    /**
     * Return the instance of the StatusBar. If this has not been explicity
     * set then it will be created.
     *
     * @return the StatusBar instance.
     * @see #setInstance
     */
    public static StatusBar getInstance() {
  if (INSTANCE == null) {
      INSTANCE = new StatusBar();
  }
        return INSTANCE;
    }

    /**
     * Sets the StatusBar instance.
     */
    public static void setInstance(StatusBar status) {
  INSTANCE = status;
    }

    /**
     * Returns the string width
     * @param s the string
     * @return the string width
     */
    protected int getWidth(String s) {
  FontMetrics fm = this.getFontMetrics(this.getFont());
  if (fm == null) {
      return 0;
  }
  return fm.stringWidth(s);
    }

    /**
     * Returns the height of a line of text
     * @return the height of a line of text
     */
    protected int getFontHeight() {
  FontMetrics fm = this.getFontMetrics(this.getFont());
  if (fm == null) {
      return 0;
  }
  return fm.getHeight();
    }

    /**
     * Returns the perferred size
     * @return the preferred size
     */
    public Dimension getPreferredSize() {
  return preferredSize;
    }

    /**
     * Sets non-transient status bar message
     * @param message the message to display on the status bar
     */
    public void setMessage(String message) {
  label.setText(message);
    }    

    //
    // MouseListener methods 
    //

    public void mouseClicked(MouseEvent evt) {}
    public void mousePressed(MouseEvent evt) {}
    public void mouseReleased(MouseEvent evt) {}

    public void mouseExited(MouseEvent evt) {
  setMessage("");
    }

    /**
     * Takes the LONG_DESCRIPTION of the Action based components
     * and sends them to the Status bar
     */
    public void mouseEntered(MouseEvent evt) {
  if (evt.getSource() instanceof AbstractButton)  {
      AbstractButton button = (AbstractButton)evt.getSource();
      Action action = button.getAction();
      if (action != null)  {
    String message = (String)action.getValue(Action.LONG_DESCRIPTION);
    setMessage(message);
      }
  }
    }

    /**
     * Helper method to recursively register all MenuElements with 
     * a mouse listener.
     */
    public void registerMouseListener(MenuElement[] elements) {
  for (int i = 0; i < elements.length; i++) {
      if (elements[i] instanceof JMenuItem) {
    ((JMenuItem)elements[i]).addMouseListener(this);
      }
      registerMouseListener(elements[i].getSubElements());
  }
    }

    /**
     * Helper method to register all components with a mouse listener.
     */
    public void registerMouseListener(Component[] components) {
  for (int i = 0; i < components.length; i++) {
      if (components[i] instanceof AbstractButton) {
    ((AbstractButton)components[i]).addMouseListener(this);
      }
  }
    }
} // end class StatusBar

   
    
    
  

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