jfcutilities.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: JFCUtilities.java,v 1.4 2001/05/07 12:34:45 kunugi Exp $
**
** Copyright (c) 2000-2001 Jeff Gay
** on behalf of ICEMail.org <http://www.icemail.org>
** Copyright (c) 1998-2000 by Timothy Gerard Endres
**
** This program is free software.
**
** You may redistribute it and/or modify it under the terms of the GNU
** General Public License as published by the Free Software Foundation.
** Version 2 of the license should be included with this distribution in
** the file LICENSE, as well as License.html. If the license is not
** included with this distribution, you may find a copy at the FSF web
** site at 'www.gnu.org' or 'www.fsf.org', or you may write to the
** Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139 USA.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE.
*/

package org.icemail.util;

import java.awt.Component;
import java.awt.Dimension;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;

import javax.swing.JPopupMenu;

import javax.swing.border.Border;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EtchedBorder;
import javax.swing.border.EmptyBorder;

/**
 * This is a class that contains useful utility functions related
 * to the JFC (Swing).
 */

public class JFCUtilities
{
  public static final Border StandardBorder =
    new CompoundBorder( new EmptyBorder( 4, 4, 4, 4 ),
                        new CompoundBorder( new EtchedBorder( EtchedBorder.RAISED ),
                                            new EmptyBorder( 4, 4, 4, 4 ) ) );
  /**
   * Swing 1.0 and 1.1 have a horrible bug with respect to popup menus.
   * Namely that they are not adjusted to be kept on-screen.
   * Here, we ensure that the popup is properly located.
   * This method will continue to work even after Sun fixes Swing...
   * However, because there is a case where we estimate the size of
   * the popup menu, one could make the argument to noop this method
   * when the bug is finally fixed.
   */
  static public Point
  computePopupLocation( MouseEvent event, Component rel, JPopupMenu popup ) {
    Dimension psz = popup.getSize();
    Dimension ssz = Toolkit.getDefaultToolkit().getScreenSize();
    Point gLoc = rel.getLocationOnScreen();
    Point result = new Point( event.getX(), event.getY() );

    gLoc.x += event.getX();
    gLoc.y += event.getY();

    if ( psz.width == 0 || psz.height == 0 ) {
      // DRAT! Now we need to "estimate"...
      int items = popup.getSubElements().length;
      psz.height = ( items * 22 );
      psz.width = 100;
    }

    psz.height += 5;

    if ( (gLoc.x + psz.width) > ssz.width ) {
      result.x -= (( gLoc.x + psz.width) - ssz.width);
      if ( (gLoc.x + result.x) < 0 )
        result.x = -(gLoc.x + event.getX());
    }

    if ( (gLoc.y + psz.height) > ssz.height ) {
      result.y -= (( gLoc.y + psz.height) - ssz.height);
      if ( (gLoc.y + result.y) < 0 )
        result.y = -gLoc.y;
    }

    return result;
  }

}