1 /*
2 * Copyright (c) 1999, 2020, 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 @SuppressWarnings("serial") // Not statically typed as Serializable
64 private final Type type;
65
66 /**
67 * The media position when the event occurred, expressed in sample frames.
68 * Note that this field is only relevant to certain events generated by data
69 * lines, such as {@code START} and {@code STOP}. For events generated by
70 * lines that do not count sample frames, and for any other events for which
71 * this value is not known, the position value should be
72 * {@link AudioSystem#NOT_SPECIFIED}.
73 *
74 * @see #getFramePosition
75 * @serial
76 */
77 private final long position;
78
79 /**
80 * Constructs a new event of the specified type, originating from the
81 * specified line.
82 *
83 * @param line the source of this event
84 * @param type the event type ({@code OPEN}, {@code CLOSE}, {@code START},
85 * or {@code STOP})
86 * @param position the number of sample frames that the line had already
87 * processed when the event occurred, or
88 * {@link AudioSystem#NOT_SPECIFIED}
89 * @throws IllegalArgumentException if {@code line} is {@code null}
90 */
91 public LineEvent(Line line, Type type, long position) {
92
93 super(line);
94 this.type = type;
95 this.position = position;
96 }
97
98 /**
99 * Obtains the audio line that is the source of this event.
100 *
101 * @return the line responsible for this event
102 */
103 public final Line getLine() {
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 return type;
115 }
116
117 /**
118 * Obtains the position in the line's audio data when the event occurred,
119 * expressed in sample frames. For example, if a source line had already
120 * played back 14 sample frames at the time it was paused, the pause event
121 * would report the line's position as 14. The next frame to be processed
122 * would be frame number 14 using zero-based numbering, or 15 using
123 * one-based numbering.
124 * <p>
125 * Note that this field is relevant only to certain events generated by data
126 * lines, such as {@code START} and {@code STOP}. For events generated by
127 * lines that do not count sample frames, and for any other events for which
128 * this value is not known, the position value should be
129 * {@link AudioSystem#NOT_SPECIFIED}.
130 *
131 * @return the line's position as a sample frame number
132 */
133 /*
134 * $$kk: 04.20.99: note to myself: should make sure our implementation is
135 * consistent with this.
136 * which is a reasonable definition....
137 */
138 public final long getFramePosition() {
139 return position;
140 }
141
142 /**
143 * Returns a string representation of the event.
144 *
145 * @return a string representation of the event
146 */
147 @Override
148 public String toString() {
149 return String.format("%s event from line %s", type, getLine());
150 }
151
152 /**
153 * The LineEvent.Type inner class identifies what kind of event occurred on
154 * a line. Static instances are provided for the common types (OPEN, CLOSE,
155 * START, and STOP).
156 *
157 * @see LineEvent#getType()
158 */
159 public static class Type {
160
161 /**
162 * Type name.
163 */
164 private final String name;
165
166 /**
167 * Constructs a new event type.
168 *
169 * @param name name of the type
170 */
171 protected Type(String name) {
172 this.name = name;
173 }
174
175 //$$fb 2002-11-26: fix for 4695001: SPEC: description of equals() method contains typo
176
177 /**
178 * Indicates whether the specified object is equal to this event type,
179 * returning {@code true} if the objects are the same.
180 *
181 * @param obj the reference object with which to compare
182 * @return {@code true} if the specified object is equal to this event
183 * type; {@code false} otherwise
184 */
185 @Override
186 public final boolean equals(Object obj) {
187 return super.equals(obj);
188 }
189
190 /**
191 * Returns a hash code value for this event type.
192 *
193 * @return a hash code value for this event type
194 */
195 @Override
196 public final int hashCode() {
197 return super.hashCode();
198 }
199
200 /**
201 * Returns type's name as the string representation of the event type.
202 *
203 * @return a string representation of the event type
204 */
205 @Override
206 public String toString() {
207 return name;
208 }
209
210 // LINE EVENT TYPE DEFINES
211
212 /**
213 * A type of event that is sent when a line opens, reserving system
214 * resources for itself.
215 *
216 * @see #CLOSE
217 * @see Line#open
218 */
219 public static final Type OPEN = new Type("Open");
220
221 /**
222 * A type of event that is sent when a line closes, freeing the system
223 * resources it had obtained when it was opened.
224 *
225 * @see #OPEN
226 * @see Line#close
227 */
228 public static final Type CLOSE = new Type("Close");
229
230 /**
231 * A type of event that is sent when a line begins to engage in active
232 * input or output of audio data in response to a
233 * {@link DataLine#start start} request.
234 *
235 * @see #STOP
236 * @see DataLine#start
237 */
238 public static final Type START = new Type("Start");
239
240 /**
241 * A type of event that is sent when a line ceases active input or
242 * output of audio data in response to a {@link DataLine#stop stop}
243 * request, or because the end of media has been reached.
244 *
245 * @see #START
246 * @see DataLine#stop
247 */
248 public static final Type STOP = new Type("Stop");
249
250 /**
251 * A type of event that is sent when a line ceases to engage in active
252 * input or output of audio data because the end of media has been
253 * reached.
254 */
255 /*
256 * ISSUE: we may want to get rid of this. Is JavaSound responsible for
257 * reporting this??
258 *
259 * [If it's decided to keep this API, the docs will need to be updated
260 * to include mention of EOM events elsewhere.]
261 */
262 //public static final Type EOM = new Type("EOM");
263
264 /**
265 * A type of event that is sent when a line begins to engage in active
266 * input or output of audio data. Examples of when this happens are when
267 * a source line begins or resumes writing data to its mixer, and when a
268 * target line begins or resumes reading data from its mixer.
269 *
270 * @see #STOP
271 * @see SourceDataLine#write
272 * @see TargetDataLine#read
273 * @see DataLine#start
274 */
275 //public static final Type ACTIVE = new Type("ACTIVE");
276
277 /**
278 * A type of event that is sent when a line ceases active input or
279 * output of audio data.
280 *
281 * @see #START
282 * @see DataLine#stop
283 */
284 //public static final Type INACTIVE = new Type("INACTIVE");
285 }
286 }