WebPChunk.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.webp.chunks;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.ByteOrder;
import java.nio.charset.StandardCharsets;
import org.apache.commons.imaging.ImagingException;
import org.apache.commons.imaging.common.BinaryFileParser;
import org.apache.commons.imaging.internal.SafeOperations;
/**
* A WebP image is composed of several chunks. This is the base class for the chunks, used by the parser.
*
* @see <a href="https://developers.google.com/speed/webp/docs/riff_container">WebP Container Specification</a>
* @since 1.0-alpha4
*/
public abstract class WebPChunk extends BinaryFileParser {
private final int type;
private final int size;
protected final byte[] bytes;
private final int chunkSize;
/**
* Create a new WebP chunk.
*
* @param type chunk type.
* @param size chunk size.
* @param bytes chunk data.
* @throws ImagingException if the chunk data and the size provided do not match.
*/
WebPChunk(final int type, final int size, final byte[] bytes) throws ImagingException {
super(ByteOrder.LITTLE_ENDIAN);
if (size != bytes.length) {
throw new ImagingException("Chunk size must match bytes length");
}
this.type = type;
this.size = size;
this.bytes = bytes;
// if chunk size is odd, a single padding byte is added
final int padding = size % 2 != 0 ? 1 : 0;
// Chunk FourCC (4 bytes) + Chunk Size (4 bytes) + Chunk Payload (n bytes) + Padding
this.chunkSize = SafeOperations.add(4, 4, size, padding);
}
/**
* Print the chunk to the given stream.
*
* @param pw a stream to write to.
* @param offset chunk offset.
* @throws ImagingException if the image is invalid.
* @throws IOException if it fails to write to the given stream.
*/
public void dump(final PrintWriter pw, final int offset) throws ImagingException, IOException {
pw.printf("Chunk %s at offset %s, length %d%n, payload size %d%n", getTypeDescription(), offset >= 0 ? String.valueOf(offset) : "unknown",
getChunkSize(), getPayloadSize());
}
/**
* @return a copy of the chunk data as bytes.
*/
public byte[] getBytes() {
return bytes.clone();
}
/**
* @return the chunk size.
*/
public int getChunkSize() {
return chunkSize;
}
/**
* @return the payload size.
*/
public int getPayloadSize() {
return size;
}
/**
* @return the chunk type.
*/
public int getType() {
return type;
}
/**
* @return the description of the chunk type.
*/
public String getTypeDescription() {
return new String(new byte[] { (byte) (type & 0xff), (byte) (type >> 8 & 0xff), (byte) (type >> 16 & 0xff), (byte) (type >> 24 & 0xff) },
StandardCharsets.UTF_8);
}
}