WebPChunkVp8l.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 org.apache.commons.imaging.ImagingException;
import org.apache.commons.imaging.internal.SafeOperations;
/**
* VP8L (lossless bitstream) chunk.
*
* <pre>{@code
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | ChunkHeader('VP8L') |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* : VP8L data :
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* }</pre>
*
* @see <a href="https://developers.google.com/speed/webp/docs/riff_container#simple_file_format_lossless">Simple File Format (Lossless)</a>
* @since 1.0-alpha4
*/
public final class WebPChunkVp8l extends WebPChunk {
private final int imageWidth;
private final int imageHeight;
private final boolean hasAlpha;
private final int versionNumber;
/**
* Create a VP8L 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.
*/
public WebPChunkVp8l(final int type, final int size, final byte[] bytes) throws ImagingException {
super(type, size, bytes);
if (bytes[0] != 0x2f || size < 5) {
throw new ImagingException("Invalid VP8L chunk");
}
final int b1 = bytes[1] & 0xFF;
final int b2 = bytes[2] & 0xFF;
final int b3 = bytes[3] & 0xFF;
final int b4 = bytes[4] & 0xFF;
this.imageWidth = b1 + ((b2 & 0b0011_1111) << 8) + 1;
this.imageHeight = SafeOperations.add((b2 & 0b1100_0000) >> 6, b3 << 2, (b4 & 0b1111) << 8, 1);
this.hasAlpha = (b4 & 0b0001_0000) != 0;
this.versionNumber = b4 >> 5;
if (versionNumber != 0) {
throw new ImagingException("VP8L version should be 0");
}
}
@Override
public void dump(final PrintWriter pw, final int offset) throws ImagingException, IOException {
super.dump(pw, offset);
pw.println(" Version Number: " + getVersionNumber());
pw.println(" Image Width: " + getImageWidth());
pw.println(" Image Height: " + getImageHeight());
pw.println(" Alpha: " + hasAlpha());
}
/**
* @return the image height.
*/
public int getImageHeight() {
return imageHeight;
}
/**
* @return the image width.
*/
public int getImageWidth() {
return imageWidth;
}
/**
* @return the version number.
*/
public int getVersionNumber() {
return versionNumber;
}
/**
* @return whether the image has an alpha channel or not.
*/
public boolean hasAlpha() {
return hasAlpha;
}
}