PngChunkItxt.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.commons.imaging.formats.png.chunks;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.zip.InflaterInputStream;
import org.apache.commons.imaging.ImagingException;
import org.apache.commons.imaging.common.Allocator;
import org.apache.commons.imaging.common.BinaryFunctions;
import org.apache.commons.imaging.formats.png.AbstractPngText;
import org.apache.commons.imaging.formats.png.PngConstants;
import org.apache.commons.io.IOUtils;
public class PngChunkItxt extends AbstractPngTextChunk {
private final String keyword;
private final String text;
/**
* The language tag defined in [RFC-3066] indicates the human language used by the translated keyword and the text. Unlike the keyword, the language tag is
* case-insensitive. It is an ISO 646.IRV:1991 [ISO 646] string consisting of hyphen-separated words of 1-8 alphanumeric characters each (for example cn,
* en-uk, no-bok, x-klingon, x-KlInGoN). If the first word is two or three letters long, it is an ISO language code [ISO-639]. If the language tag is empty,
* the language is unspecified.
*/
private final String languageTag;
private final String translatedKeyword;
public PngChunkItxt(final int length, final int chunkType, final int crc, final byte[] bytes) throws ImagingException, IOException {
super(length, chunkType, crc, bytes);
int terminator = BinaryFunctions.findNull(bytes, "PNG iTXt chunk keyword is not terminated.");
keyword = new String(bytes, 0, terminator, StandardCharsets.ISO_8859_1);
int index = terminator + 1;
final int compressionFlag = bytes[index++];
if (compressionFlag != 0 && compressionFlag != 1) {
throw new ImagingException("PNG iTXt chunk has invalid compression flag: " + compressionFlag);
}
final boolean compressed = compressionFlag == 1;
final int compressionMethod = bytes[index++];
if (compressed && compressionMethod != PngConstants.COMPRESSION_DEFLATE_INFLATE) {
throw new ImagingException("PNG iTXt chunk has unexpected compression method: " + compressionMethod);
}
terminator = BinaryFunctions.findNull(bytes, index, "PNG iTXt chunk language tag is not terminated.");
languageTag = new String(bytes, index, terminator - index, StandardCharsets.ISO_8859_1);
index = terminator + 1;
terminator = BinaryFunctions.findNull(bytes, index, "PNG iTXt chunk translated keyword is not terminated.");
translatedKeyword = new String(bytes, index, terminator - index, StandardCharsets.UTF_8);
index = terminator + 1;
if (compressed) {
final int compressedTextLength = bytes.length - index;
final byte[] compressedText = Allocator.byteArray(compressedTextLength);
System.arraycopy(bytes, index, compressedText, 0, compressedTextLength);
text = new String(IOUtils.toByteArray(new InflaterInputStream(new ByteArrayInputStream(compressedText))), StandardCharsets.UTF_8);
} else {
text = new String(bytes, index, bytes.length - index, StandardCharsets.UTF_8);
}
}
@Override
public AbstractPngText getContents() {
return new AbstractPngText.Itxt(keyword, text, languageTag, translatedKeyword);
}
/**
* @return Gets the keyword.
*/
@Override
public String getKeyword() {
return keyword;
}
/**
* @return Gets the text.
*/
@Override
public String getText() {
return text;
}
public String getTranslatedKeyword() {
return translatedKeyword;
}
}