Java tutorial
/* * Copyright (c) 2000, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.imageio; import javax.imageio.metadata.IIOMetadata; /** * An interface providing metadata transcoding capability. * * <p> Any image may be transcoded (written to a different format * than the one it was originally stored in) simply by performing * a read operation followed by a write operation. However, loss * of data may occur in this process due to format differences. * * <p> In general, the best results will be achieved when * format-specific metadata objects can be created to encapsulate as * much information about the image and its associated metadata as * possible, in terms that are understood by the specific * {@code ImageWriter} used to perform the encoding. * * <p> An {@code ImageTranscoder} may be used to convert the * {@code IIOMetadata} objects supplied by the * {@code ImageReader} (representing per-stream and per-image * metadata) into corresponding objects suitable for encoding by a * particular {@code ImageWriter}. In the case where the methods * of this interface are being called directly on an * {@code ImageWriter}, the output will be suitable for that * writer. * * <p> The internal details of converting an {@code IIOMetadata} * object into a writer-specific format will vary according to the * context of the operation. Typically, an {@code ImageWriter} * will inspect the incoming object to see if it implements additional * interfaces with which the writer is familiar. This might be the * case, for example, if the object was obtained by means of a read * operation on a reader plug-in written by the same vendor as the * writer. In this case, the writer may access the incoming object by * means of its plug-in specific interfaces. In this case, the * re-encoding may be close to lossless if the image file format is * kept constant. If the format is changing, the writer may still * attempt to preserve as much information as possible. * * <p> If the incoming object does not implement any additional * interfaces known to the writer, the writer has no choice but to * access it via the standard {@code IIOMetadata} interfaces such * as the tree view provided by {@code IIOMetadata.getAsTree}. * In this case, there is likely to be significant loss of * information. * * <p> An independent {@code ImageTranscoder} essentially takes * on the same role as the writer plug-in in the above examples. It * must be familiar with the private interfaces used by both the * reader and writer plug-ins, and manually instantiate an object that * will be usable by the writer. The resulting metadata objects may * be used by the writer directly. * * <p> No independent implementations of {@code ImageTranscoder} * are provided as part of the standard API. Instead, the intention * of this interface is to provide a way for implementations to be * created and discovered by applications as the need arises. * */ public interface ImageTranscoder { /** * Returns an {@code IIOMetadata} object that may be used for * encoding and optionally modified using its document interfaces * or other interfaces specific to the writer plug-in that will be * used for encoding. * * <p> An optional {@code ImageWriteParam} may be supplied * for cases where it may affect the structure of the stream * metadata. * * <p> If the supplied {@code ImageWriteParam} contains * optional setting values not understood by this writer or * transcoder, they will be ignored. * * @param inData an {@code IIOMetadata} object representing * stream metadata, used to initialize the state of the returned * object. * @param param an {@code ImageWriteParam} that will be used to * encode the image, or {@code null}. * * @return an {@code IIOMetadata} object, or * {@code null} if the plug-in does not provide metadata * encoding capabilities. * * @exception IllegalArgumentException if {@code inData} is * {@code null}. */ IIOMetadata convertStreamMetadata(IIOMetadata inData, ImageWriteParam param); /** * Returns an {@code IIOMetadata} object that may be used for * encoding and optionally modified using its document interfaces * or other interfaces specific to the writer plug-in that will be * used for encoding. * * <p> An optional {@code ImageWriteParam} may be supplied * for cases where it may affect the structure of the image * metadata. * * <p> If the supplied {@code ImageWriteParam} contains * optional setting values not understood by this writer or * transcoder, they will be ignored. * * @param inData an {@code IIOMetadata} object representing * image metadata, used to initialize the state of the returned * object. * @param imageType an {@code ImageTypeSpecifier} indicating * the layout and color information of the image with which the * metadata will be associated. * @param param an {@code ImageWriteParam} that will be used to * encode the image, or {@code null}. * * @return an {@code IIOMetadata} object, * or {@code null} if the plug-in does not provide * metadata encoding capabilities. * * @exception IllegalArgumentException if either of * {@code inData} or {@code imageType} is * {@code null}. */ IIOMetadata convertImageMetadata(IIOMetadata inData, ImageTypeSpecifier imageType, ImageWriteParam param); }