    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.imaging.common;
    018
    019import java.io.ByteArrayOutputStream;
    020import java.io.IOException;
    021import java.util.zip.DataFormatException;
    022import java.util.zip.DeflaterOutputStream;
    023import java.util.zip.Inflater;
    024
    025import org.apache.commons.imaging.ImageReadException;
    026import org.apache.commons.imaging.ImageWriteException;
    027
    028/**
    029 * <p>
    030 * Utility class to compress/decompress bytes using the ZLIB deflate/inflate
    031 * compression.
    032 * </p>
    033 *
    034 * <p>
    035 * <a href="http://www.ietf.org/rfc/rfc1951.txt">RFC 1951 - DEFLATE Compressed
    036 * Data Format Specification version 1.3</a>
    037 * </p>
    038 */
    039public class ZlibDeflate {
    040
    041    /**
    042     * Compress the byte[] using ZLIB deflate decompression.
    043     *
    044     * @param bytes The bytes to decompress
    045     * @param expectedSize The expected size of the decompressed byte[].
    046     *
    047     * @return The decompressed bytes.
    048     * @throws ImageReadException if the bytes could not be decompressed.
    049     * @see Inflater
    050     */
    051    public static byte[] decompress(final byte[] bytes, final int expectedSize) throws ImageReadException {
    052        try {
    053            final Inflater inflater = new Inflater();
    054            inflater.setInput(bytes);
    055            final byte[] result = new byte[expectedSize];
    056            inflater.inflate(result);
    057            return result;
    058        } catch (final DataFormatException e) {
    059            throw new ImageReadException("Unable to decompress image", e);
    060        }
    061    }
    062
    063    /**
    064     * Compress the byte[] using ZLIB deflate compression.
    065     *
    066     * @param bytes The bytes to compress
    067     *
    068     * @return The compressed bytes.
    069     * @throws ImageWriteException if the bytes could not be compressed.
    070     * @see DeflaterOutputStream
    071     */
    072    public static byte[] compress(final byte[] bytes) throws ImageWriteException {
    073        final ByteArrayOutputStream out = new ByteArrayOutputStream(bytes.length / 2);
    074        try (DeflaterOutputStream compressOut = new DeflaterOutputStream(out)) {
    075            compressOut.write(bytes);
    076        } catch (final IOException e) {
    077            throw new ImageWriteException("Unable to compress image", e);
    078        }
    079        return out.toByteArray();
    080    }
    081
    082}