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}