J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 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 | } |