1 /*
2 * Copyright 2000 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.imageio;
27
28 import javax.imageio.metadata.IIOMetadata;
29
30 /**
31 * An interface providing metadata transcoding capability.
32 *
33 * <p> Any image may be transcoded (written to a different format
34 * than the one it was originally stored in) simply by performing
35 * a read operation followed by a write operation. However, loss
36 * of data may occur in this process due to format differences.
37 *
38 * <p> In general, the best results will be achieved when
39 * format-specific metadata objects can be created to encapsulate as
40 * much information about the image and its associated metadata as
41 * possible, in terms that are understood by the specific
42 * <code>ImageWriter</code> used to perform the encoding.
43 *
44 * <p> An <code>ImageTranscoder</code> may be used to convert the
45 * <code>IIOMetadata</code> objects supplied by the
46 * <code>ImageReader</code> (representing per-stream and per-image
47 * metadata) into corresponding objects suitable for encoding by a
48 * particular <code>ImageWriter</code>. In the case where the methods
49 * of this interface are being called directly on an
50 * <code>ImageWriter</code>, the output will be suitable for that
51 * writer.
52 *
53 * <p> The internal details of converting an <code>IIOMetadata</code>
54 * object into a writer-specific format will vary according to the
55 * context of the operation. Typically, an <code>ImageWriter</code>
56 * will inspect the incoming object to see if it implements additional
57 * interfaces with which the writer is familiar. This might be the
58 * case, for example, if the object was obtained by means of a read
59 * operation on a reader plug-in written by the same vendor as the
60 * writer. In this case, the writer may access the incoming object by
61 * means of its plug-in specific interfaces. In this case, the
62 * re-encoding may be close to lossless if the image file format is
63 * kept constant. If the format is changing, the writer may still
64 * attempt to preserve as much information as possible.
65 *
66 * <p> If the incoming object does not implement any additional
67 * interfaces known to the writer, the writer has no choice but to
68 * access it via the standard <code>IIOMetadata</code> interfaces such
69 * as the tree view provided by <code>IIOMetadata.getAsTree</code>.
70 * In this case, there is likely to be significant loss of
71 * information.
72 *
73 * <p> An independent <code>ImageTranscoder</code> essentially takes
74 * on the same role as the writer plug-in in the above examples. It
75 * must be familiar with the private interfaces used by both the
76 * reader and writer plug-ins, and manually instantiate an object that
77 * will be usable by the writer. The resulting metadata objects may
78 * be used by the writer directly.
79 *
80 * <p> No independent implementations of <code>ImageTranscoder</code>
81 * are provided as part of the standard API. Instead, the intention
82 * of this interface is to provide a way for implementations to be
83 * created and discovered by applications as the need arises.
84 *
85 */
86 public interface ImageTranscoder {
87
88 /**
89 * Returns an <code>IIOMetadata</code> object that may be used for
90 * encoding and optionally modified using its document interfaces
91 * or other interfaces specific to the writer plug-in that will be
92 * used for encoding.
93 *
94 * <p> An optional <code>ImageWriteParam</code> may be supplied
95 * for cases where it may affect the structure of the stream
96 * metadata.
97 *
98 * <p> If the supplied <code>ImageWriteParam</code> contains
99 * optional setting values not understood by this writer or
100 * transcoder, they will be ignored.
101 *
102 * @param inData an <code>IIOMetadata</code> object representing
103 * stream metadata, used to initialize the state of the returned
104 * object.
105 * @param param an <code>ImageWriteParam</code> that will be used to
106 * encode the image, or <code>null</code>.
107 *
108 * @return an <code>IIOMetadata</code> object, or
109 * <code>null</code> if the plug-in does not provide metadata
110 * encoding capabilities.
111 *
112 * @exception IllegalArgumentException if <code>inData</code> is
113 * <code>null</code>.
114 */
115 IIOMetadata convertStreamMetadata(IIOMetadata inData,
116 ImageWriteParam param);
117
118 /**
119 * Returns an <code>IIOMetadata</code> object that may be used for
120 * encoding and optionally modified using its document interfaces
121 * or other interfaces specific to the writer plug-in that will be
122 * used for encoding.
123 *
124 * <p> An optional <code>ImageWriteParam</code> may be supplied
125 * for cases where it may affect the structure of the image
126 * metadata.
127 *
128 * <p> If the supplied <code>ImageWriteParam</code> contains
129 * optional setting values not understood by this writer or
130 * transcoder, they will be ignored.
131 *
132 * @param inData an <code>IIOMetadata</code> object representing
133 * image metadata, used to initialize the state of the returned
134 * object.
135 * @param imageType an <code>ImageTypeSpecifier</code> indicating
136 * the layout and color information of the image with which the
137 * metadata will be associated.
138 * @param param an <code>ImageWriteParam</code> that will be used to
139 * encode the image, or <code>null</code>.
140 *
141 * @return an <code>IIOMetadata</code> object,
142 * or <code>null</code> if the plug-in does not provide
143 * metadata encoding capabilities.
144 *
145 * @exception IllegalArgumentException if either of
146 * <code>inData</code> or <code>imageType</code> is
147 * <code>null</code>.
148 */
149 IIOMetadata convertImageMetadata(IIOMetadata inData,
150 ImageTypeSpecifier imageType,
151 ImageWriteParam param);
152 }
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