1 /* 2 * Copyright (c) 1999, 2018, 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 return (Line)getSource(); 104 } 105 106 /** 107 * Obtains the event's type. 108 * 109 * @return this event's type ({@link Type#OPEN}, {@link Type#CLOSE}, 110 * {@link Type#START}, or {@link Type#STOP}) 111 */ 112 public final Type getType() { 113 return type; 114 } 115 116 /** 117 * Obtains the position in the line's audio data when the event occurred, 118 * expressed in sample frames. For example, if a source line had already 119 * played back 14 sample frames at the time it was paused, the pause event 120 * would report the line's position as 14. The next frame to be processed 121 * would be frame number 14 using zero-based numbering, or 15 using 122 * one-based numbering. 123 * <p> 124 * Note that this field is relevant only to certain events generated by data 125 * lines, such as {@code START} and {@code STOP}. For events generated by 126 * lines that do not count sample frames, and for any other events for which 127 * this value is not known, the position value should be 128 * {@link AudioSystem#NOT_SPECIFIED}. 129 * 130 * @return the line's position as a sample frame number 131 */ 132 /* 133 * $$kk: 04.20.99: note to myself: should make sure our implementation is 134 * consistent with this. 135 * which is a reasonable definition.... 136 */ 137 public final long getFramePosition() { 138 return position; 139 } 140 141 /** 142 * Obtains a string representation of the event. The contents of the string 143 * may vary between implementations of Java Sound. 144 * 145 * @return a string describing the event 146 */ 147 @Override 148 public String toString() { 149 String sType = ""; 150 if (type != null) sType = type.toString()+" "; 151 String sLine; 152 if (getLine() == null) { 153 sLine = "null"; 154 } else { 155 sLine = getLine().toString(); 156 } 157 return new String(sType + "event from line " + sLine); 158 } 159 160 /** 161 * The LineEvent.Type inner class identifies what kind of event occurred on 162 * a line. Static instances are provided for the common types (OPEN, CLOSE, 163 * START, and STOP). 164 * 165 * @see LineEvent#getType() 166 */ 167 public static class Type { 168 169 /** 170 * Type name. 171 */ 172 private final String name; 173 174 /** 175 * Constructs a new event type. 176 * 177 * @param name name of the type 178 */ 179 protected Type(String name) { 180 this.name = name; 181 } 182 183 //$$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 the same. 188 * 189 * @param obj the reference object with which to compare 190 * @return {@code true} if the specified object is equal to this event 191 * type; {@code false} otherwise 192 */ 193 @Override 194 public final boolean equals(Object obj) { 195 return super.equals(obj); 196 } 197 198 /** 199 * Returns a hash code value for this event type. 200 * 201 * @return a hash code value for this event type 202 */ 203 @Override 204 public final int hashCode() { 205 return super.hashCode(); 206 } 207 208 /** 209 * Returns the type name as the string representation. 210 * 211 * @return the type name as the string representation 212 */ 213 @Override 214 public String toString() { 215 return name; 216 } 217 218 // LINE EVENT TYPE DEFINES 219 220 /** 221 * A type of event that is sent when a line opens, reserving system 222 * resources for itself. 223 * 224 * @see #CLOSE 225 * @see Line#open 226 */ 227 public static final Type OPEN = new Type("Open"); 228 229 /** 230 * A type of event that is sent when a line closes, freeing the system 231 * resources it had obtained when it was opened. 232 * 233 * @see #OPEN 234 * @see Line#close 235 */ 236 public static final Type CLOSE = new Type("Close"); 237 238 /** 239 * A type of event that is sent when a line begins to engage in active 240 * input or output of audio data in response to a 241 * {@link DataLine#start start} request. 242 * 243 * @see #STOP 244 * @see DataLine#start 245 */ 246 public static final Type START = new Type("Start"); 247 248 /** 249 * A type of event that is sent when a line ceases active input or 250 * output of audio data in response to a {@link DataLine#stop stop} 251 * request, or because the end of media has been reached. 252 * 253 * @see #START 254 * @see DataLine#stop 255 */ 256 public static final Type STOP = new Type("Stop"); 257 258 /** 259 * A type of event that is sent when a line ceases to engage in active 260 * input or output of audio data because the end of media has been 261 * reached. 262 */ 263 /* 264 * ISSUE: we may want to get rid of this. Is JavaSound responsible for 265 * reporting this?? 266 * 267 * [If it's decided to keep this API, the docs will need to be updated 268 * to include mention of EOM events elsewhere.] 269 */ 270 //public static final Type EOM = new Type("EOM"); 271 272 /** 273 * A type of event that is sent when a line begins to engage in active 274 * input or output of audio data. Examples of when this happens are when 275 * a source line begins or resumes writing data to its mixer, and when a 276 * target line begins or resumes reading data from its mixer. 277 * 278 * @see #STOP 279 * @see SourceDataLine#write 280 * @see TargetDataLine#read 281 * @see DataLine#start 282 */ 283 //public static final Type ACTIVE = new Type("ACTIVE"); 284 285 /** 286 * A type of event that is sent when a line ceases active input or 287 * output of audio data. 288 * 289 * @see #START 290 * @see DataLine#stop 291 */ 292 //public static final Type INACTIVE = new Type("INACTIVE"); 293 } 294 }