/*
 * 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.
 */

/* $Id$ */

package org.apache.xmlgraphics.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.
 *
 */
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;
}
