gcc/libjava/classpath/javax/swing/PopupFactory.java

/* PopupFactory.java --
   Copyright (C) 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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02110-1301 USA.

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permission to link this library with independent modules to produce an
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package javax.swing;

import java.awt.Component;
import java.awt.Dimension;
import java.awt.Point;


/**
 * A factory for <code>Popup</code> objects. These are used to
 * managed little windows that float over everything else,
 * typically containing a popup menu.
 *
 * @since 1.4
 *
 * @author Sascha Brawer (brawer@dandelis.ch)
 */
public class PopupFactory
{
  /**
   * The shared factory object.
   *
   * @see #getSharedInstance
   * @see #setSharedInstance
   */
  private static PopupFactory sharedFactory;


  /**
   * Constructs a new <code>PopupFactory</code>. Usually, a single
   * <code>PopupFactory</code> is shared among multiple consumers
   * of <code>Popup</code>. Use {@link #getSharedInstance} to retrieve
   * the current factory.
   */
  public PopupFactory()
  {
    // Nothing to do here.
  }


  /**
   * Sets the shared factory.
   *
   * @param factory the PopupFactory that future invocations of
   *        {@link #getSharedInstance} will return.
   *
   * @throws IllegalArgumentException if <code>factory</code>
   *         is <code>null</code>.
   */
  public static void setSharedInstance(PopupFactory factory)
  {
    if (factory == null)
      throw new IllegalArgumentException();

    /* Swing is not designed to be thread-safe, so there is no
     * need to synchronize the access to the global variable.
     */
    sharedFactory = factory;
  }


  /**
   * Retrieves the shared factory, creating a new factory if
   * necessary.
   *
   * @return a <code>PopupFactory</code> that can be used
   *         to create <code>Popup</code> objects.
   */
  public static PopupFactory getSharedInstance()
  {
    /* Swing is not designed to be thread-safe, so there is no
     * need to synchronize the access to the global variable.
     */
    if (sharedFactory == null)
      sharedFactory = new PopupFactory();

    return sharedFactory;
  }


  /**
   * Creates a new <code>Popup</code> given its owner,
   * contents and the screen position where the popup
   * will appear.
   *
   * @param owner the Component to which <code>x</code> and
   *        <code>y</code> are relative, or <code>null</code> for
   *        placing the popup relative to the origin of the screen.
   *
   * @param contents the contents that will be displayed inside
   *        the <code>Popup</code>.
   *
   * @param x the horizontal position where the Popup will appear.
   *
   * @param y the vertical position where the Popup will appear.
   *
   * @throws IllegalArgumentException if <code>contents</code>
   *         is <code>null</code>.
   */
  public Popup getPopup(Component owner, Component contents,
                        int x, int y)
  {
    Popup popup = null;
    // By default we enable lightweight popups since they are more efficient
    // than heavyweight popups.
    boolean lightweightEnabled = true;
    // Special case JPopupMenu here, since it supports a lightweightEnabled
    // flag that we must respect.
    if (contents instanceof JPopupMenu)
      {
        JPopupMenu menu = (JPopupMenu) contents;
        lightweightEnabled = menu.isLightWeightPopupEnabled();
      }

    // If we have a root pane and the contents fits within the root pane and
    // lightweight popups are enabled, than we can use a lightweight popup.
    JRootPane root = SwingUtilities.getRootPane(owner);
    if (root != null)
      {
        Point rootLoc = root.getLocationOnScreen();
        Dimension contentsSize = contents.getSize();
        Dimension rootSize = root.getSize();
        if (x >= rootLoc.x && y > rootLoc.y
            && (x - rootLoc.x) + contentsSize.width < rootSize.width
            && (y - rootLoc.y) + contentsSize.height < rootSize.height)      
          popup = new Popup.LightweightPopup(owner, contents, x, y);
        else
          popup = new Popup.JWindowPopup(owner, contents, x, y);
      }
    else
      popup = new Popup.JWindowPopup(owner, contents, x, y);
    return popup;
  }
}