Get Point For Centering : SwingUtilities « Swing « Java Tutorial

1. Java Tutorial
2. Swing
3. SwingUtilities

/*
 * $Id: WindowUtils.java,v 1.16 2009/05/25 16:37:52 kschaefe Exp $
 *
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.Window;

/**
 * Encapsulates various utilities for windows (ie: <code>Frame</code> and
 * <code>Dialog</code> objects and descendants, in particular).
 *
 * @author Richard Bair
 */
public class Utils {
  public static Point getPointForCentering(Window window) {
    Rectangle usableBounds = getUsableDeviceBounds(window);
    int screenWidth = usableBounds.width;
    int screenHeight = usableBounds.height;
    int width = window.getWidth();
    int height = window.getHeight();
    
    return new Point(((screenWidth - width) / 2) + usableBounds.x,
            ((screenHeight - height) / 2) + usableBounds.y);
}
  /**
   * <p>
   * Returns the <code>Point</code> at which a window should be placed to
   * center that window on the screen.
   * </p>
   * <p>
   * Some thought was taken as to whether to implement a method such as this,
   * or to simply make a method that, given a window, will center it.  It was
   * decided that it is better to not alter an object within a method.
   * </p>
   *
   * @param window The window to calculate the center point for.  This object
   *               can not be null.
   *
   * @return the <code>Point</code> at which the window should be placed to
   *         center that window on the screen.
   */


  private static Rectangle getUsableDeviceBounds(Window window) {
      Window owner = window.getOwner();
      GraphicsConfiguration gc = null;
      
      if (owner == null) {
          gc = GraphicsEnvironment.getLocalGraphicsEnvironment()
                  .getDefaultScreenDevice().getDefaultConfiguration();
      } else {
          gc = owner.getGraphicsConfiguration();
      }
      
      Insets insets = Toolkit.getDefaultToolkit().getScreenInsets(gc);
      Rectangle bounds = gc.getBounds();
      bounds.x += insets.left;
      bounds.y += insets.top;
      bounds.width -= (insets.left + insets.right);
      bounds.height -= (insets.top + insets.bottom);
      
      return bounds;
  }
}