1 /*
2 * Copyright (c) 1999, 2017, 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 import java.util.EventObject;
29
30 /**
31 * The {@code LineEvent} class encapsulates information that a line sends its
32 * listeners whenever the line opens, closes, starts, or stops. Each of these
33 * four state changes is represented by a corresponding type of event. A
34 * listener receives the event as a parameter to its
35 * {@link LineListener#update update} method. By querying the event, the
36 * listener can learn the type of event, the line responsible for the event, and
37 * how much data the line had processed when the event occurred.
38 * <p>
39 * Although this class implements Serializable, attempts to serialize a
40 * {@code LineEvent} object will fail.
41 *
42 * @author Kara Kytle
43 * @see Line
44 * @see LineListener#update
45 * @since 1.3
46 *
47 * @serial exclude
48 */
49 public class LineEvent extends EventObject {
50
51 /**
52 * Use serialVersionUID from JDK 1.3 for interoperability.
53 */
54 private static final long serialVersionUID = -1274246333383880410L;
55
56 /**
57 * The kind of line event ({@code OPEN}, {@code CLOSE}, {@code START}, or
58 * {@code STOP}).
59 *
60 * @see #getType
61 * @serial
62 */
63 private final Type type;
64
65 /**
66 * The media position when the event occurred, expressed in sample frames.
67 * Note that this field is only relevant to certain events generated by data
68 * lines, such as {@code START} and {@code STOP}. For events generated by
69 * lines that do not count sample frames, and for any other events for which
70 * this value is not known, the position value should be
71 * {@link AudioSystem#NOT_SPECIFIED}.
72 *
73 * @see #getFramePosition
74 * @serial
75 */
76 private final long position;
77
78 /**
79 * Constructs a new event of the specified type, originating from the
80 * specified line.
81 *
82 * @param line the source of this event
83 * @param type the event type ({@code OPEN}, {@code CLOSE}, {@code START},
84 * or {@code STOP})
85 * @param position the number of sample frames that the line had already
86 * processed when the event occurred, or
87 * {@link AudioSystem#NOT_SPECIFIED}
88 * @throws IllegalArgumentException if {@code line} is {@code null}
89 */
90 public LineEvent(Line line, Type type, long position) {
91
92 super(line);
93 this.type = type;
94 this.position = position;
95 }
96
97 /**
98 * Obtains the audio line that is the source of this event.
99 *
100 * @return the line responsible for this event
101 */
102 public final Line getLine() {
103
104 return (Line)getSource();
105 }
106
107 /**
108 * Obtains the event's type.
109 *
110 * @return this event's type ({@link Type#OPEN}, {@link Type#CLOSE},
111 * {@link Type#START}, or {@link Type#STOP})
112 */
113 public final Type getType() {
114
115 return type;
116 }
117
118 /**
119 * Obtains the position in the line's audio data when the event occurred,
120 * expressed in sample frames. For example, if a source line had already
121 * played back 14 sample frames at the time it was paused, the pause event
122 * would report the line's position as 14. The next frame to be processed
123 * would be frame number 14 using zero-based numbering, or 15 using
124 * one-based numbering.
125 * <p>
126 * Note that this field is relevant only to certain events generated by data
127 * lines, such as {@code START} and {@code STOP}. For events generated by
128 * lines that do not count sample frames, and for any other events for which
129 * this value is not known, the position value should be
130 * {@link AudioSystem#NOT_SPECIFIED}.
131 *
132 * @return the line's position as a sample frame number
133 */
134 /*
135 * $$kk: 04.20.99: note to myself: should make sure our implementation is
136 * consistent with this.
137 * which is a reasonable definition....
138 */
139 public final long getFramePosition() {
140
141 return position;
142 }
143
144 /**
145 * Obtains a string representation of the event. The contents of the string
146 * may vary between implementations of Java Sound.
147 *
148 * @return a string describing the event
149 */
150 @Override
151 public String toString() {
152 String sType = "";
153 if (type != null) sType = type.toString()+" ";
154 String sLine;
155 if (getLine() == null) {
156 sLine = "null";
157 } else {
158 sLine = getLine().toString();
159 }
160 return new String(sType + "event from line " + sLine);
161 }
162
163 /**
164 * The LineEvent.Type inner class identifies what kind of event occurred on
165 * a line. Static instances are provided for the common types (OPEN, CLOSE,
166 * START, and STOP).
167 *
168 * @see LineEvent#getType()
169 */
170 public static class Type {
171
172 /**
173 * Type name.
174 */
175 private final String name;
176
177 /**
178 * Constructs a new event type.
179 *
180 * @param name name of the type
181 */
182 protected Type(String name) {
183 this.name = name;
184 }
185
186 //$$fb 2002-11-26: fix for 4695001: SPEC: description of equals() method contains typo
187
188 /**
189 * Indicates whether the specified object is equal to this event type,
190 * returning {@code true} if the objects are the same.
191 *
192 * @param obj the reference object with which to compare
193 * @return {@code true} if the specified object is equal to this event
194 * type; {@code false} otherwise
195 */
196 @Override
197 public final boolean equals(Object obj) {
198 return super.equals(obj);
199 }
200
201 /**
202 * Returns a hash code value for this event type.
203 *
204 * @return a hash code value for this event type
205 */
206 @Override
207 public final int hashCode() {
208 return super.hashCode();
209 }
210
211 /**
212 * Returns the type name as the string representation.
213 *
214 * @return the type name as the string representation
215 */
216 @Override
217 public String toString() {
218 return name;
219 }
220
221 // LINE EVENT TYPE DEFINES
222
223 /**
224 * A type of event that is sent when a line opens, reserving system
225 * resources for itself.
226 *
227 * @see #CLOSE
228 * @see Line#open
229 */
230 public static final Type OPEN = new Type("Open");
231
232 /**
233 * A type of event that is sent when a line closes, freeing the system
234 * resources it had obtained when it was opened.
235 *
236 * @see #OPEN
237 * @see Line#close
238 */
239 public static final Type CLOSE = new Type("Close");
240
241 /**
242 * A type of event that is sent when a line begins to engage in active
243 * input or output of audio data in response to a
244 * {@link DataLine#start start} request.
245 *
246 * @see #STOP
247 * @see DataLine#start
248 */
249 public static final Type START = new Type("Start");
250
251 /**
252 * A type of event that is sent when a line ceases active input or
253 * output of audio data in response to a {@link DataLine#stop stop}
254 * request, or because the end of media has been reached.
255 *
256 * @see #START
257 * @see DataLine#stop
258 */
259 public static final Type STOP = new Type("Stop");
260
261 /**
262 * A type of event that is sent when a line ceases to engage in active
263 * input or output of audio data because the end of media has been
264 * reached.
265 */
266 /*
267 * ISSUE: we may want to get rid of this. Is JavaSound responsible for
268 * reporting this??
269 *
270 * [If it's decided to keep this API, the docs will need to be updated
271 * to include mention of EOM events elsewhere.]
272 */
273 //public static final Type EOM = new Type("EOM");
274
275 /**
276 * A type of event that is sent when a line begins to engage in active
277 * input or output of audio data. Examples of when this happens are when
278 * a source line begins or resumes writing data to its mixer, and when a
279 * target line begins or resumes reading data from its mixer.
280 *
281 * @see #STOP
282 * @see SourceDataLine#write
283 * @see TargetDataLine#read
284 * @see DataLine#start
285 */
286 //public static final Type ACTIVE = new Type("ACTIVE");
287
288 /**
289 * A type of event that is sent when a line ceases active input or
290 * output of audio data.
291 *
292 * @see #START
293 * @see DataLine#stop
294 */
295 //public static final Type INACTIVE = new Type("INACTIVE");
296 }
297 }