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
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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
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23 * questions.
24 */
25
26package javax.sound.sampled;
27
28import 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 */
49public 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}
298