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 @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 * $$kk: 04.20.99: note to myself: should make sure our implementation is 135 * consistent with this. 136 * which is a reasonable definition.... 137 */ 138 public final long getFramePosition() { 139 return position; 140 } 141 142 /** 143 * Obtains a string representation of the event. The contents of the string 144 * may vary between implementations of Java Sound. 145 * 146 * @return a string describing the event 147 */ 148 @Override 149 public String toString() { 150 String sType = ""; 151 if (type != null) sType = type.toString()+" "; 152 String sLine; 153 if (getLine() == null) { 154 sLine = "null"; 155 } else { 156 sLine = getLine().toString(); 157 } 158 return new String(sType + "event from line " + sLine); 159 } 160 161 /** 162 * The LineEvent.Type inner class identifies what kind of event occurred on 163 * a line. Static instances are provided for the common types (OPEN, CLOSE, 164 * START, and STOP). 165 * 166 * @see LineEvent#getType() 167 */ 168 public static class Type { 169 170 /** 171 * Type name. 172 */ 173 private final String name; 174 175 /** 176 * Constructs a new event type. 177 * 178 * @param name name of the type 179 */ 180 protected Type(String name) { 181 this.name = name; 182 } 183 184 //$$fb 2002-11-26: fix for 4695001: SPEC: description of equals() method contains typo 185 186 /** 187 * Indicates whether the specified object is equal to this event type, 188 * returning {@code true} if the objects are the same. 189 * 190 * @param obj the reference object with which to compare 191 * @return {@code true} if the specified object is equal to this event 192 * type; {@code false} otherwise 193 */ 194 @Override 195 public final boolean equals(Object obj) { 196 return super.equals(obj); 197 } 198 199 /** 200 * Returns a hash code value for this event type. 201 * 202 * @return a hash code value for this event type 203 */ 204 @Override 205 public final int hashCode() { 206 return super.hashCode(); 207 } 208 209 /** 210 * Returns the type name as the string representation. 211 * 212 * @return the type name as the string representation 213 */ 214 @Override 215 public String toString() { 216 return name; 217 } 218 219 // LINE EVENT TYPE DEFINES 220 221 /** 222 * A type of event that is sent when a line opens, reserving system 223 * resources for itself. 224 * 225 * @see #CLOSE 226 * @see Line#open 227 */ 228 public static final Type OPEN = new Type("Open"); 229 230 /** 231 * A type of event that is sent when a line closes, freeing the system 232 * resources it had obtained when it was opened. 233 * 234 * @see #OPEN 235 * @see Line#close 236 */ 237 public static final Type CLOSE = new Type("Close"); 238 239 /** 240 * A type of event that is sent when a line begins to engage in active 241 * input or output of audio data in response to a 242 * {@link DataLine#start start} request. 243 * 244 * @see #STOP 245 * @see DataLine#start 246 */ 247 public static final Type START = new Type("Start"); 248 249 /** 250 * A type of event that is sent when a line ceases active input or 251 * output of audio data in response to a {@link DataLine#stop stop} 252 * request, or because the end of media has been reached. 253 * 254 * @see #START 255 * @see DataLine#stop 256 */ 257 public static final Type STOP = new Type("Stop"); 258 259 /** 260 * A type of event that is sent when a line ceases to engage in active 261 * input or output of audio data because the end of media has been 262 * reached. 263 */ 264 /* 265 * ISSUE: we may want to get rid of this. Is JavaSound responsible for 266 * reporting this?? 267 * 268 * [If it's decided to keep this API, the docs will need to be updated 269 * to include mention of EOM events elsewhere.] 270 */ 271 //public static final Type EOM = new Type("EOM"); 272 273 /** 274 * A type of event that is sent when a line begins to engage in active 275 * input or output of audio data. Examples of when this happens are when 276 * a source line begins or resumes writing data to its mixer, and when a 277 * target line begins or resumes reading data from its mixer. 278 * 279 * @see #STOP 280 * @see SourceDataLine#write 281 * @see TargetDataLine#read 282 * @see DataLine#start 283 */ 284 //public static final Type ACTIVE = new Type("ACTIVE"); 285 286 /** 287 * A type of event that is sent when a line ceases active input or 288 * output of audio data. 289 * 290 * @see #START 291 * @see DataLine#stop 292 */ 293 //public static final Type INACTIVE = new Type("INACTIVE"); 294 } 295 }