1 /*
2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.sound.sampled;
27
28 /**
29 * The <code>LineEvent</code> class encapsulates information that a line
30 * sends its listeners whenever the line opens, closes, starts, or stops.
31 * Each of these four state changes is represented by a corresponding
32 * type of event. A listener receives the event as a parameter to its
33 * {@link LineListener#update update} method. By querying the event,
34 * the listener can learn the type of event, the line responsible for
35 * the event, and how much data the line had processed when the event occurred.
36 *
37 * <p>Although this class implements Serializable, attempts to
38 * serialize a <code>LineEvent</code> object will fail.
39 *
40 * @author Kara Kytle
41 *
42 * @see Line
43 * @see LineListener#update
44 * @since 1.3
45 *
46 * @serial exclude
47 */
48 public class LineEvent extends java.util.EventObject {
49 private static final long serialVersionUID = -1274246333383880410L;
50
51 // INSTANCE VARIABLES
52
53 /**
54 * The kind of line event (<code>OPEN</code>, <code>CLOSE</code>,
55 * <code>START</code>, or <code>STOP</code>).
56 * @see #getType
57 * @serial
58 */
59 private final Type type;
60
61 /**
62 * The media position when the event occurred, expressed in sample frames.
63 * Note that this field is only relevant to certain events generated by
64 * data lines, such as <code>START</code> and <code>STOP</code>. For
65 * events generated by lines that do not count sample frames, and for any
66 * other events for which this value is not known, the position value
67 * should be {@link AudioSystem#NOT_SPECIFIED}.
68 * @serial
69 * @see #getFramePosition
70 */
71 private final long position;
72
73
74 /**
75 * Constructs a new event of the specified type, originating from the specified line.
76 * @param line the source of this event
77 * @param type the event type (<code>OPEN</code>, <code>CLOSE</code>, <code>START</code>, or <code>STOP</code>)
78 * @param position the number of sample frames that the line had already processed when the event occurred,
79 * or {@link AudioSystem#NOT_SPECIFIED}
80 *
81 * @throws IllegalArgumentException if <code>line</code> is
82 * <code>null</code>.
83 */
84 public LineEvent(Line line, Type type, long position) {
85
86 super(line);
87 this.type = type;
88 this.position = position;
89 }
90
91 /**
92 * Obtains the audio line that is the source of this event.
93 * @return the line responsible for this event
94 */
95 public final Line getLine() {
96
97 return (Line)getSource();
98 }
99
100
101 /**
102 * Obtains the event's type.
103 * @return this event's type ({@link Type#OPEN}, {@link Type#CLOSE},
104 * {@link Type#START}, or {@link Type#STOP})
105 */
106 public final Type getType() {
107
108 return type;
109 }
110
111 /**
112 * Obtains the position in the line's audio data when the event occurred, expressed in sample frames.
113 * For example, if a source line had already played back 14 sample frames at the time it was
114 * paused, the pause event would report the line's position as 14. The next frame to be processed
115 * would be frame number 14 using zero-based numbering, or 15 using one-based numbering.
116 * <p>
117 * Note that this field is relevant only to certain events generated by
118 * data lines, such as <code>START</code> and <code>STOP</code>. For
119 * events generated by lines that do not count sample frames, and for any
120 * other events for which this value is not known, the position value
121 * should be {@link AudioSystem#NOT_SPECIFIED}.
122 *
123 * @return the line's position as a sample frame number
124 */
125 /*
126 * $$kk: 04.20.99: note to myself: should make sure our implementation is consistent with this.
127 * which is a reasonable definition....
128 */
129 public final long getFramePosition() {
130
131 return position;
132 }
133
134 /**
135 * Obtains a string representation of the event. The contents of the string may vary
136 * between implementations of Java Sound.
137 * @return a string describing the event.
138 */
139 public String toString() {
140 String sType = "";
141 if (type != null) sType = type.toString()+" ";
142 String sLine;
143 if (getLine() == null) {
144 sLine = "null";
145 } else {
146 sLine = getLine().toString();
147 }
148 return new String(sType + "event from line " + sLine);
149 }
150
151
152 /**
153 * The LineEvent.Type inner class identifies what kind of event occurred on a line.
154 * Static instances are provided for the common types (OPEN, CLOSE, START, and STOP).
155 *
156 * @see LineEvent#getType()
157 */
158 public static class Type {
159
160
161 /**
162 * Type name.
163 */
164 // $$kk: 03.25.99: why can't this be final??
165 private /*final*/ String name;
166
167 /**
168 * Constructs a new event type.
169 * @param name name of the type
170 */
171 protected Type(String name) {
172 this.name = name;
173 }
174
175
176 //$$fb 2002-11-26: fix for 4695001: SPEC: description of equals() method contains typo
177 /**
178 * Indicates whether the specified object is equal to this event type,
179 * returning <code>true</code> if the objects are identical.
180 * @param obj the reference object with which to compare
181 * @return <code>true</code> if this event type is the same as
182 * <code>obj</code>; <code>false</code> otherwise
183 */
184 public final boolean equals(Object obj) {
185 return super.equals(obj);
186 }
187
188
189 /**
190 * Finalizes the hashcode method.
191 */
192 public final int hashCode() {
193 return super.hashCode();
194 }
195
196
197 /**
198 * Returns the type name as the string representation.
199 */
200 public String toString() {
201 return name;
202 }
203
204
205 // LINE EVENT TYPE DEFINES
206
207 /**
208 * A type of event that is sent when a line opens, reserving system
209 * resources for itself.
210 * @see #CLOSE
211 * @see Line#open
212 */
213 public static final Type OPEN = new Type("Open");
214
215
216 /**
217 * A type of event that is sent when a line closes, freeing the system
218 * resources it had obtained when it was opened.
219 * @see #OPEN
220 * @see Line#close
221 */
222 public static final Type CLOSE = new Type("Close");
223
224
225 /**
226 * A type of event that is sent when a line begins to engage in active
227 * input or output of audio data in response to a
228 * {@link DataLine#start start} request.
229 * @see #STOP
230 * @see DataLine#start
231 */
232 public static final Type START = new Type("Start");
233
234
235 /**
236 * A type of event that is sent when a line ceases active input or output
237 * of audio data in response to a {@link DataLine#stop stop} request,
238 * or because the end of media has been reached.
239 * @see #START
240 * @see DataLine#stop
241 */
242 public static final Type STOP = new Type("Stop");
243
244
245 /**
246 * A type of event that is sent when a line ceases to engage in active
247 * input or output of audio data because the end of media has been reached.
248 */
249 /*
250 * ISSUE: we may want to get rid of this. Is JavaSound
251 * responsible for reporting this??
252 *
253 * [If it's decided to keep this API, the docs will need to be updated to include mention
254 * of EOM events elsewhere.]
255 */
256 //public static final Type EOM = new Type("EOM");
257
258
259 /**
260 * A type of event that is sent when a line begins to engage in active
261 * input or output of audio data. Examples of when this happens are
262 * when a source line begins or resumes writing data to its mixer, and
263 * when a target line begins or resumes reading data from its mixer.
264 * @see #STOP
265 * @see SourceDataLine#write
266 * @see TargetDataLine#read
267 * @see DataLine#start
268 */
269 //public static final Type ACTIVE = new Type("ACTIVE");
270
271
272 /**
273 * A type of event that is sent when a line ceases active input or output
274 * of audio data.
275 * @see #START
276 * @see DataLine#stop
277 */
278 //public static final Type INACTIVE = new Type("INACTIVE");
279
280 } // class Type
281
282 } // class LineEvent