001 /*
002 * Copyright 2000-2004 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package javax.imageio.spi;
027
028 import java.io.File;
029 import java.io.IOException;
030 import javax.imageio.stream.ImageOutputStream;
031
032 /**
033 * The service provider interface (SPI) for
034 * <code>ImageOutputStream</code>s. For more information on service
035 * provider interfaces, see the class comment for the
036 * <code>IIORegistry</code> class.
037 *
038 * <p> This interface allows arbitrary objects to be "wrapped" by
039 * instances of <code>ImageOutputStream</code>. For example, a
040 * particular <code>ImageOutputStreamSpi</code> might allow a generic
041 * <code>OutputStream</code> to be used as a destination; another
042 * might output to a <code>File</code> or to a device such as a serial
043 * port.
044 *
045 * <p> By treating the creation of <code>ImageOutputStream</code>s as
046 * a pluggable service, it becomes possible to handle future output
047 * destinations without changing the API. Also, high-performance
048 * implementations of <code>ImageOutputStream</code> (for example,
049 * native implementations for a particular platform) can be installed
050 * and used transparently by applications.
051 *
052 * @see IIORegistry
053 * @see javax.imageio.stream.ImageOutputStream
054 *
055 * @version 0.5
056 */
057 public abstract class ImageOutputStreamSpi extends IIOServiceProvider {
058
059 /**
060 * A <code>Class</code> object indicating the legal object type
061 * for use by the <code>createInputStreamInstance</code> method.
062 */
063 protected Class<?> outputClass;
064
065 /**
066 * Constructs a blank <code>ImageOutputStreamSpi</code>. It is up
067 * to the subclass to initialize instance variables and/or
068 * override method implementations in order to provide working
069 * versions of all methods.
070 */
071 protected ImageOutputStreamSpi() {
072 }
073
074 /**
075 * Constructs an <code>ImageOutputStreamSpi</code> with a given
076 * set of values.
077 *
078 * @param vendorName the vendor name.
079 * @param version a version identifier.
080 * @param outputClass a <code>Class</code> object indicating the
081 * legal object type for use by the
082 * <code>createOutputStreamInstance</code> method.
083 *
084 * @exception IllegalArgumentException if <code>vendorName</code>
085 * is <code>null</code>.
086 * @exception IllegalArgumentException if <code>version</code>
087 * is <code>null</code>.
088 */
089 public ImageOutputStreamSpi(String vendorName, String version,
090 Class<?> outputClass) {
091 super (vendorName, version);
092 this .outputClass = outputClass;
093 }
094
095 /**
096 * Returns a <code>Class</code> object representing the class or
097 * interface type that must be implemented by an output
098 * destination in order to be "wrapped" in an
099 * <code>ImageOutputStream</code> via the
100 * <code>createOutputStreamInstance</code> method.
101 *
102 * <p> Typical return values might include
103 * <code>OutputStream.class</code> or <code>File.class</code>, but
104 * any class may be used.
105 *
106 * @return a <code>Class</code> variable.
107 *
108 * @see #createOutputStreamInstance(Object, boolean, File)
109 */
110 public Class<?> getOutputClass() {
111 return outputClass;
112 }
113
114 /**
115 * Returns <code>true</code> if the <code>ImageOutputStream</code>
116 * implementation associated with this service provider can
117 * optionally make use of a cache <code>File</code> for improved
118 * performance and/or memory footrprint. If <code>false</code>,
119 * the value of the <code>cacheFile</code> argument to
120 * <code>createOutputStreamInstance</code> will be ignored.
121 *
122 * <p> The default implementation returns <code>false</code>.
123 *
124 * @return <code>true</code> if a cache file can be used by the
125 * output streams created by this service provider.
126 */
127 public boolean canUseCacheFile() {
128 return false;
129 }
130
131 /**
132 * Returns <code>true</code> if the <code>ImageOutputStream</code>
133 * implementation associated with this service provider requires
134 * the use of a cache <code>File</code>.
135 *
136 * <p> The default implementation returns <code>false</code>.
137 *
138 * @return <code>true</code> if a cache file is needed by the
139 * output streams created by this service provider.
140 */
141 public boolean needsCacheFile() {
142 return false;
143 }
144
145 /**
146 * Returns an instance of the <code>ImageOutputStream</code>
147 * implementation associated with this service provider. If the
148 * use of a cache file is optional, the <code>useCache</code>
149 * parameter will be consulted. Where a cache is required, or
150 * not applicable, the value of <code>useCache</code> will be ignored.
151 *
152 * @param output an object of the class type returned by
153 * <code>getOutputClass</code>.
154 * @param useCache a <code>boolean</code> indicating whether a
155 * cache file should be used, in cases where it is optional.
156 * @param cacheDir a <code>File</code> indicating where the
157 * cache file should be created, or <code>null</code> to use the
158 * system directory.
159 *
160 * @return an <code>ImageOutputStream</code> instance.
161 *
162 * @exception IllegalArgumentException if <code>output</code> is
163 * not an instance of the correct class or is <code>null</code>.
164 * @exception IllegalArgumentException if a cache file is needed,
165 * but <code>cacheDir</code> is non-<code>null</code> and is not a
166 * directory.
167 * @exception IOException if a cache file is needed but cannot be
168 * created.
169 *
170 * @see #getOutputClass
171 */
172 public abstract ImageOutputStream createOutputStreamInstance(
173 Object output, boolean useCache, File cacheDir)
174 throws IOException;
175
176 /**
177 * Returns an instance of the <code>ImageOutputStream</code>
178 * implementation associated with this service provider. A cache
179 * file will be created in the system-dependent default
180 * temporary-file directory, if needed.
181 *
182 * @param output an object of the class type returned by
183 * <code>getOutputClass</code>.
184 *
185 * @return an <code>ImageOutputStream</code> instance.
186 *
187 * @exception IllegalArgumentException if <code>output</code> is
188 * not an instance of the correct class or is <code>null</code>.
189 * @exception IOException if a cache file is needed but cannot be
190 * created.
191 *
192 * @see #getOutputClass()
193 */
194 public ImageOutputStream createOutputStreamInstance(Object output)
195 throws IOException {
196 return createOutputStreamInstance(output, true, null);
197 }
198 }
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