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