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 }