libjava/java/awt/event/HierarchyEvent.java

   1 /* HierarchyEvent.java -- generated for a change in hierarchy
   2    Copyright (C) 2000, 2002 Free Software Foundation
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.awt.event;
  40
  41 import java.awt.AWTEvent;
  42 import java.awt.Component;
  43 import java.awt.Container;
  44
  45 /**
  46  * This class represents an event generated for an ancestor component which
  47  * may affect this component. These events normally do not need to be handled
  48  * by the application, since the AWT system automatically takes care of them.
  49  *
  50  * <p>There are two types of hierarchy events. The first type is handled by
  51  * HierarchyListener, and includes addition or removal of an ancestor, or
  52  * an ancestor changing its on-screen status (visible and/or displayble). The
  53  * second type is handled by HierarchyBoundsListener, and includes resizing
  54  * or moving of an ancestor.
  55  *
  56  * @author Bryce McKinlay
  57  * @see HierarchyListener
  58  * @see HierarchyBoundsAdapter
  59  * @see HierarchyBoundsListener
  60  * @since 1.3
  61  * @status updated to 1.4
  62  */
  63 public class HierarchyEvent extends AWTEvent
  64 {
  65   /**
  66    * Compatible with JDK 1.3+.
  67    */
  68   private static final long serialVersionUID = -5337576970038043990L;
  69
  70   /** This is the first id in the range of ids used by this class. */
  71   public static final int HIERARCHY_FIRST = 1400;
  72
  73   /** This id indicates that the hierarchy tree changed. */
  74   public static final int HIERARCHY_CHANGED = 1400;
  75
  76   /** This id indicates that an ancestor was moved. */
  77   public static final int ANCESTOR_MOVED = 1401;
  78
  79   /** This id indicates that an ancestor was resized. */
  80   public static final int ANCESTOR_RESIZED = 1402;
  81
  82   /** This is the last id in the range of ids used by this class. */
  83   public static final int HIERARCHY_LAST = 1402;
  84
  85   /** This indicates that the HIERARCHY_CHANGED is a changed parent. */
  86   public static final int PARENT_CHANGED = 1;
  87
  88   /**
  89    * This indicates that the HIERARCHY_CHANGED is caused by a change in
  90    * displayability.
  91    *
  92    * @see Component#isDisplayable()
  93    * @see Component#addNotify()
  94    * @see Component#removeNotify()
  95    */
  96   public static final int DISPLAYABILITY_CHANGED = 2;
  97
  98   /**
  99    * This indicates that the HIERARCHY_CHANGED is a changed visibility.
 100    *
 101    * @see Component#isShowing()
 102    * @see Component#addNotify()
 103    * @see Component#removeNotify()
 104    * @see Component#show()
 105    * @see Component#hide()
 106    */
 107   public static final int SHOWING_CHANGED = 4;
 108
 109   /**
 110    * The component at the top of the changed hierarchy.
 111    *
 112    * @serial the top component changed
 113    */
 114   private final Component changed;
 115
 116   /**
 117    * The parent of this component, either before or after the change depending
 118    * on the type of change.
 119    *
 120    * @serial the parent component changed
 121    */
 122   private final Container changedParent;
 123
 124   /**
 125    * The bitmask of HIERARCHY_CHANGED event types.
 126    *
 127    * @serial the change flags
 128    */
 129   private final long changeFlags;
 130
 131   /**
 132    * Initializes a new instance of <code>HierarchyEvent</code> with the
 133    * specified parameters. Note that an invalid id leads to unspecified
 134    * results.
 135    *
 136    * @param source the component whose hierarchy changed
 137    * @param id the event id
 138    * @param changed the top component in the tree of changed hierarchy
 139    * @param changedParent the updated parent of this object
 140    * @throws IllegalArgumentException if source is null
 141    */
 142   public HierarchyEvent(Component source, int id, Component changed,
 143                         Container changedParent)
 144   {
 145     this(source, id, changed, changedParent, 0);
 146   }
 147
 148   /**
 149    * Initializes a new instance of <code>HierarchyEvent</code> with the
 150    * specified parameters. Note that an invalid id leads to unspecified
 151    * results.
 152    *
 153    * @param source the component whose hierarchy changed
 154    * @param id the event id
 155    * @param changed the top component in the tree of changed hierarchy
 156    * @param changedParent the updated parent of this object
 157    * @param changeFlags the bitmask of specific HIERARCHY_CHANGED events
 158    * @throws IllegalArgumentException if source is null
 159    */
 160   public HierarchyEvent(Component source, int id, Component changed,
 161                         Container changedParent, long changeFlags)
 162   {
 163     super(source, id);
 164     this.changed = changed;
 165     this.changedParent = changedParent;
 166     this.changeFlags = changeFlags;
 167   }
 168
 169   /**
 170    * This method returns the event source as a <code>Component</code>. If the
 171    * source has subsequently been modified to a non-Component, this returns
 172    * null.
 173    *
 174    * @return the event source as a <code>Component</code>, or null
 175    */
 176   public Component getComponent()
 177   {
 178     return source instanceof Component ? (Component) source : null;
 179   }
 180
 181   /**
 182    * Returns the component at the top of the hierarchy which changed.
 183    *
 184    * @return the top changed component
 185    */
 186   public Component getChanged()
 187   {
 188     return changed;
 189   }
 190
 191   /**
 192    * Returns the parent of the component listed in <code>getChanged()</code>.
 193    * If the cause of this event was <code>Container.add</code>, this is the
 194    * new parent; if the cause was <code>Container.remove</code>, this is the
 195    * old parent; otherwise it is the unchanged parent.
 196    *
 197    * @return the parent container of the changed component
 198    */
 199   public Container getChangedParent()
 200   {
 201     return changedParent;
 202   }
 203
 204   /**
 205    * If this is a HIERARCHY_CHANGED event, this returns a bitmask of the
 206    * types of changes that took place.
 207    *
 208    * @return the bitwise or of hierarchy change types, or 0
 209    * @see #PARENT_CHANGED
 210    * @see #DISPLAYABILITY_CHANGED
 211    * @see #SHOWING_CHANGED
 212    */
 213   public long getChangeFlags()
 214   {
 215     return changeFlags;
 216   }
 217
 218   /**
 219    * This method returns a string identifying this event. This is the field
 220    * name of the id type, followed by a parenthesized listing of the changed
 221    * component and its parent container. In addition, if the type is
 222    * HIERARCHY_CHANGED, the flags preceed the changed component, in the
 223    * order PARENT_CHANGED, DISPLAYABILITY_CHANGED, and SHOWING_CHANGED.
 224    *
 225    * @return a string identifying this event
 226    */
 227   public String paramString()
 228   {
 229     StringBuffer r = new StringBuffer();
 230     switch (id)
 231       {
 232       case HIERARCHY_CHANGED:
 233         r.append("HIERARCHY_CHANGED (");
 234         if ((changeFlags & PARENT_CHANGED) != 0)
 235           r.append("PARENT_CHANGED,");
 236         if ((changeFlags & DISPLAYABILITY_CHANGED) != 0)
 237           r.append("DISPLAYABILITY_CHANGED,");
 238         if ((changeFlags & SHOWING_CHANGED) != 0)
 239           r.append("SHOWING_CHANGED,");
 240         break;
 241       case ANCESTOR_MOVED:
 242         r.append("ANCESTOR_MOVED (");
 243         break;
 244       case ANCESTOR_RESIZED:
 245         r.append("ANCESTOR_RESIZED (");
 246         break;
 247       default:
 248         return "unknown type";
 249       }
 250     r.append(changed).append(',').append(changedParent).append(')');
 251     return r.toString();
 252   }
 253 } // class HierarchyEvent