001/* HierarchyEvent.java -- generated for a change in hierarchy
002   Copyright (C) 2000, 2002 Free Software Foundation
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt.event;
040
041import gnu.java.lang.CPStringBuilder;
042
043import java.awt.AWTEvent;
044import java.awt.Component;
045import java.awt.Container;
046
047/**
048 * This class represents an event generated for an ancestor component which
049 * may affect this component. These events normally do not need to be handled
050 * by the application, since the AWT system automatically takes care of them.
051 *
052 * <p>There are two types of hierarchy events. The first type is handled by
053 * HierarchyListener, and includes addition or removal of an ancestor, or
054 * an ancestor changing its on-screen status (visible and/or displayble). The
055 * second type is handled by HierarchyBoundsListener, and includes resizing
056 * or moving of an ancestor.
057 *
058 * @author Bryce McKinlay
059 * @see HierarchyListener
060 * @see HierarchyBoundsAdapter
061 * @see HierarchyBoundsListener
062 * @since 1.3
063 * @status updated to 1.4
064 */
065public class HierarchyEvent extends AWTEvent
066{
067  /**
068   * Compatible with JDK 1.3+.
069   */
070  private static final long serialVersionUID = -5337576970038043990L;
071
072  /** This is the first id in the range of ids used by this class. */
073  public static final int HIERARCHY_FIRST = 1400;
074
075  /** This id indicates that the hierarchy tree changed. */
076  public static final int HIERARCHY_CHANGED = 1400;
077
078  /** This id indicates that an ancestor was moved. */
079  public static final int ANCESTOR_MOVED = 1401;
080
081  /** This id indicates that an ancestor was resized. */
082  public static final int ANCESTOR_RESIZED = 1402;
083
084  /** This is the last id in the range of ids used by this class. */
085  public static final int HIERARCHY_LAST = 1402;
086
087  /** This indicates that the HIERARCHY_CHANGED is a changed parent. */
088  public static final int PARENT_CHANGED = 1;
089
090  /**
091   * This indicates that the HIERARCHY_CHANGED is caused by a change in
092   * displayability.
093   *
094   * @see Component#isDisplayable()
095   * @see Component#addNotify()
096   * @see Component#removeNotify()
097   */
098  public static final int DISPLAYABILITY_CHANGED = 2;
099
100  /**
101   * This indicates that the HIERARCHY_CHANGED is a changed visibility.
102   *
103   * @see Component#isShowing()
104   * @see Component#addNotify()
105   * @see Component#removeNotify()
106   * @see Component#show()
107   * @see Component#hide()
108   */
109  public static final int SHOWING_CHANGED = 4;
110
111  /**
112   * The component at the top of the changed hierarchy.
113   *
114   * @serial the top component changed
115   */
116  private final Component changed;
117
118  /**
119   * The parent of this component, either before or after the change depending
120   * on the type of change.
121   *
122   * @serial the parent component changed
123   */
124  private final Container changedParent;
125
126  /**
127   * The bitmask of HIERARCHY_CHANGED event types.
128   *
129   * @serial the change flags
130   */
131  private final long changeFlags;
132
133  /**
134   * Initializes a new instance of <code>HierarchyEvent</code> with the
135   * specified parameters. Note that an invalid id leads to unspecified
136   * results.
137   *
138   * @param source the component whose hierarchy changed
139   * @param id the event id
140   * @param changed the top component in the tree of changed hierarchy
141   * @param changedParent the updated parent of this object
142   * @throws IllegalArgumentException if source is null
143   */
144  public HierarchyEvent(Component source, int id, Component changed,
145                        Container changedParent)
146  {
147    this(source, id, changed, changedParent, 0);
148  }
149
150  /**
151   * Initializes a new instance of <code>HierarchyEvent</code> with the
152   * specified parameters. Note that an invalid id leads to unspecified
153   * results.
154   *
155   * @param source the component whose hierarchy changed
156   * @param id the event id
157   * @param changed the top component in the tree of changed hierarchy
158   * @param changedParent the updated parent of this object
159   * @param changeFlags the bitmask of specific HIERARCHY_CHANGED events
160   * @throws IllegalArgumentException if source is null
161   */
162  public HierarchyEvent(Component source, int id, Component changed,
163                        Container changedParent, long changeFlags)
164  {
165    super(source, id);
166    this.changed = changed;
167    this.changedParent = changedParent;
168    this.changeFlags = changeFlags;
169  }
170
171  /**
172   * This method returns the event source as a <code>Component</code>. If the
173   * source has subsequently been modified to a non-Component, this returns
174   * null.
175   *
176   * @return the event source as a <code>Component</code>, or null
177   */
178  public Component getComponent()
179  {
180    return source instanceof Component ? (Component) source : null;
181  }
182
183  /**
184   * Returns the component at the top of the hierarchy which changed.
185   *
186   * @return the top changed component
187   */
188  public Component getChanged()
189  {
190    return changed;
191  }
192
193  /**
194   * Returns the parent of the component listed in <code>getChanged()</code>.
195   * If the cause of this event was <code>Container.add</code>, this is the
196   * new parent; if the cause was <code>Container.remove</code>, this is the
197   * old parent; otherwise it is the unchanged parent.
198   *
199   * @return the parent container of the changed component
200   */
201  public Container getChangedParent()
202  {
203    return changedParent;
204  }
205
206  /**
207   * If this is a HIERARCHY_CHANGED event, this returns a bitmask of the
208   * types of changes that took place.
209   *
210   * @return the bitwise or of hierarchy change types, or 0
211   * @see #PARENT_CHANGED
212   * @see #DISPLAYABILITY_CHANGED
213   * @see #SHOWING_CHANGED
214   */
215  public long getChangeFlags()
216  {
217    return changeFlags;
218  }
219
220  /**
221   * This method returns a string identifying this event. This is the field
222   * name of the id type, followed by a parenthesized listing of the changed
223   * component and its parent container. In addition, if the type is
224   * HIERARCHY_CHANGED, the flags preceed the changed component, in the
225   * order PARENT_CHANGED, DISPLAYABILITY_CHANGED, and SHOWING_CHANGED.
226   *
227   * @return a string identifying this event
228   */
229  public String paramString()
230  {
231    CPStringBuilder r = new CPStringBuilder();
232    switch (id)
233      {
234      case HIERARCHY_CHANGED:
235        r.append("HIERARCHY_CHANGED (");
236        if ((changeFlags & PARENT_CHANGED) != 0)
237          r.append("PARENT_CHANGED,");
238        if ((changeFlags & DISPLAYABILITY_CHANGED) != 0)
239          r.append("DISPLAYABILITY_CHANGED,");
240        if ((changeFlags & SHOWING_CHANGED) != 0)
241          r.append("SHOWING_CHANGED,");
242        break;
243      case ANCESTOR_MOVED:
244        r.append("ANCESTOR_MOVED (");
245        break;
246      case ANCESTOR_RESIZED:
247        r.append("ANCESTOR_RESIZED (");
248        break;
249      default:
250        return "unknown type";
251      }
252    r.append(changed).append(',').append(changedParent).append(')');
253    return r.toString();
254  }
255} // class HierarchyEvent