sources/org/apache/batik/ext/awt/image/codec/util/ImageDecoder.java

/*

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */
package org.apache.batik.ext.awt.image.codec.util;

import java.awt.image.Raster;
import java.awt.image.RenderedImage;
import java.io.IOException;

/**
 * An interface describing objects that transform an InputStream into a
 * BufferedImage or Raster.
 *
 * @version $Id$
 */
public interface ImageDecoder {

    /**
     * Returns the current parameters as an instance of the
     * ImageDecodeParam interface.  Concrete implementations of this
     * interface will return corresponding concrete implementations of
     * the ImageDecodeParam interface.  For example, a JPEGImageDecoder
     * will return an instance of JPEGDecodeParam.
     */
    ImageDecodeParam getParam();

    /**
     * Sets the current parameters to an instance of the
     * ImageDecodeParam interface.  Concrete implementations
     * of ImageDecoder may throw a RuntimeException if the
     * param argument is not an instance of the appropriate
     * subclass or subinterface.  For example, a JPEGImageDecoder
     * will expect param to be an instance of JPEGDecodeParam.
     */
    void setParam(ImageDecodeParam param);

    /** Returns the SeekableStream associated with this ImageDecoder. */
    SeekableStream getInputStream();

    /** Returns the number of pages present in the current stream. */
    int getNumPages() throws IOException;

    /**
     * Returns a Raster that contains the decoded contents of the
     * SeekableStream associated with this ImageDecoder.  Only
     * the first page of a multi-page image is decoded.
     */
    Raster decodeAsRaster() throws IOException;

    /**
     * Returns a Raster that contains the decoded contents of the
     * SeekableStream associated with this ImageDecoder.
     * The given page of a multi-page image is decoded.  If
     * the page does not exist, an IOException will be thrown.
     * Page numbering begins at zero.
     *
     * @param page The page to be decoded.
     */
    Raster decodeAsRaster(int page) throws IOException;

    /**
     * Returns a RenderedImage that contains the decoded contents of the
     * SeekableStream associated with this ImageDecoder.  Only
     * the first page of a multi-page image is decoded.
     */
    RenderedImage decodeAsRenderedImage() throws IOException;

    /**
     * Returns a RenderedImage that contains the decoded contents of the
     * SeekableStream associated with this ImageDecoder.
     * The given page of a multi-page image is decoded.  If
     * the page does not exist, an IOException will be thrown.
     * Page numbering begins at zero.
     *
     * @param page The page to be decoded.
     */
    RenderedImage decodeAsRenderedImage(int page) throws IOException;
}