org.apache.commons.imaging.formats.png.chunks.PngChunkScal Maven / Gradle / Ivy
/*
* 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 org.apache.commons.imaging.ImageReadException;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import static org.apache.commons.imaging.common.BinaryFunctions.findNull;
public class PngChunkScal extends PngChunk {
public final double unitsPerPixelXAxis;
public final double unitsPerPixelYAxis;
public final int unitSpecifier;
public PngChunkScal(final int length, final int chunkType, final int crc, final byte[] bytes)
throws ImageReadException, IOException {
super(length, chunkType, crc, bytes);
unitSpecifier = bytes[0];
if (unitSpecifier != 1 && unitSpecifier != 2) {
throw new ImageReadException("PNG sCAL invalid unit specifier: " + unitSpecifier);
}
final int separator = findNull(bytes);
if (separator < 0) {
throw new ImageReadException("PNG sCAL x and y axis value separator not found.");
}
final int xIndex = 1;
final String xStr = new String(bytes, xIndex, separator - 1, StandardCharsets.ISO_8859_1);
unitsPerPixelXAxis = toDouble(xStr);
final int yIndex = separator + 1;
if (yIndex >= length) {
throw new ImageReadException("PNG sCAL chunk missing the y axis value.");
}
final String yStr = new String(bytes, yIndex, length - yIndex, StandardCharsets.ISO_8859_1);
unitsPerPixelYAxis = toDouble(yStr);
}
private double toDouble(final String str) throws ImageReadException {
try {
return Double.valueOf(str);
} catch (final NumberFormatException e) {
throw new ImageReadException("PNG sCAL error reading axis value - " + str);
}
}
}