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.formats.png.chunks;
018
019import java.io.ByteArrayInputStream;
020import java.io.IOException;
021import java.nio.charset.StandardCharsets;
022import java.util.zip.InflaterInputStream;
023
024import org.apache.commons.imaging.ImagingException;
025import org.apache.commons.imaging.common.Allocator;
026import org.apache.commons.imaging.common.BinaryFunctions;
027import org.apache.commons.imaging.formats.png.AbstractPngText;
028import org.apache.commons.imaging.formats.png.PngConstants;
029import org.apache.commons.io.IOUtils;
030
031public final class PngChunkZtxt extends AbstractPngTextChunk {
032
033    private final String keyword;
034    private final String text;
035
036    public PngChunkZtxt(final int length, final int chunkType, final int crc, final byte[] bytes) throws ImagingException, IOException {
037        super(length, chunkType, crc, bytes);
038
039        int index = BinaryFunctions.indexOf0(bytes, "PNG zTXt chunk keyword is unterminated.");
040        keyword = new String(bytes, 0, index, StandardCharsets.ISO_8859_1);
041        index++;
042
043        final int compressionMethod = bytes[index++];
044        if (compressionMethod != PngConstants.COMPRESSION_DEFLATE_INFLATE) {
045            throw new ImagingException("PNG zTXt chunk has unexpected compression method: " + compressionMethod);
046        }
047
048        final int compressedTextLength = bytes.length - index;
049        final byte[] compressedText = Allocator.byteArray(compressedTextLength);
050        System.arraycopy(bytes, index, compressedText, 0, compressedTextLength);
051
052        text = new String(IOUtils.toByteArray(new InflaterInputStream(new ByteArrayInputStream(compressedText))), StandardCharsets.ISO_8859_1);
053    }
054
055    @Override
056    public AbstractPngText getContents() {
057        return new AbstractPngText.Ztxt(keyword, text);
058    }
059
060    /**
061     * Gets the keyword.
062     *
063     * @return the keyword.
064     */
065    @Override
066    public String getKeyword() {
067        return keyword;
068    }
069
070    /**
071     * Gets the text.
072     *
073     * @return the text.
074     */
075    @Override
076    public String getText() {
077        return text;
078    }
079
080}