001 /* HierarchyEvent.java -- generated for a change in hierarchy
002 Copyright (C) 2000, 2002 Free Software Foundation
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
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017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt.event;
040
041 import java.awt.AWTEvent;
042 import java.awt.Component;
043 import java.awt.Container;
044
045 /**
046 * This class represents an event generated for an ancestor component which
047 * may affect this component. These events normally do not need to be handled
048 * by the application, since the AWT system automatically takes care of them.
049 *
050 * <p>There are two types of hierarchy events. The first type is handled by
051 * HierarchyListener, and includes addition or removal of an ancestor, or
052 * an ancestor changing its on-screen status (visible and/or displayble). The
053 * second type is handled by HierarchyBoundsListener, and includes resizing
054 * or moving of an ancestor.
055 *
056 * @author Bryce McKinlay
057 * @see HierarchyListener
058 * @see HierarchyBoundsAdapter
059 * @see HierarchyBoundsListener
060 * @since 1.3
061 * @status updated to 1.4
062 */
063 public class HierarchyEvent extends AWTEvent
064 {
065 /**
066 * Compatible with JDK 1.3+.
067 */
068 private static final long serialVersionUID = -5337576970038043990L;
069
070 /** This is the first id in the range of ids used by this class. */
071 public static final int HIERARCHY_FIRST = 1400;
072
073 /** This id indicates that the hierarchy tree changed. */
074 public static final int HIERARCHY_CHANGED = 1400;
075
076 /** This id indicates that an ancestor was moved. */
077 public static final int ANCESTOR_MOVED = 1401;
078
079 /** This id indicates that an ancestor was resized. */
080 public static final int ANCESTOR_RESIZED = 1402;
081
082 /** This is the last id in the range of ids used by this class. */
083 public static final int HIERARCHY_LAST = 1402;
084
085 /** This indicates that the HIERARCHY_CHANGED is a changed parent. */
086 public static final int PARENT_CHANGED = 1;
087
088 /**
089 * This indicates that the HIERARCHY_CHANGED is caused by a change in
090 * displayability.
091 *
092 * @see Component#isDisplayable()
093 * @see Component#addNotify()
094 * @see Component#removeNotify()
095 */
096 public static final int DISPLAYABILITY_CHANGED = 2;
097
098 /**
099 * 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