    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.webp.chunks;
    018
    019import java.io.IOException;
    020import java.io.PrintWriter;
    021
    022import org.apache.commons.imaging.ImagingException;
    023import org.apache.commons.imaging.internal.SafeOperations;
    024
    025/**
    026 * VP8L (lossless bitstream) chunk.
    027 *
    028 * <pre>{@code
    029 *  0                   1                   2                   3
    030 *  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
    031 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    032 * |                      ChunkHeader('VP8L')                      |
    033 * |                                                               |
    034 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    035 * :                           VP8L data                           :
    036 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    037 * }</pre>
    038 *
    039 * @see <a href="https://developers.google.com/speed/webp/docs/riff_container#simple_file_format_lossless">Simple File Format (Lossless)</a>
    040 * @since 1.0.0-alpha4
    041 */
    042public final class WebPChunkVp8l extends AbstractWebPChunk {
    043    private final int imageWidth;
    044    private final int imageHeight;
    045    private final boolean hasAlpha;
    046    private final int versionNumber;
    047
    048    /**
    049     * Create a VP8L chunk.
    050     *
    051     * @param type  chunk type.
    052     * @param size  chunk size.
    053     * @param bytes chunk data.
    054     * @throws ImagingException if the chunk data and the size provided do not match.
    055     */
    056    public WebPChunkVp8l(final int type, final int size, final byte[] bytes) throws ImagingException {
    057        super(type, size, bytes);
    058
    059        if (bytes[0] != 0x2f || size < 5) {
    060            throw new ImagingException("Invalid VP8L chunk");
    061        }
    062
    063        final int b1 = bytes[1] & 0xFF;
    064        final int b2 = bytes[2] & 0xFF;
    065        final int b3 = bytes[3] & 0xFF;
    066        final int b4 = bytes[4] & 0xFF;
    067
    068        this.imageWidth = b1 + ((b2 & 0b0011_1111) << 8) + 1;
    069        this.imageHeight = SafeOperations.add((b2 & 0b1100_0000) >> 6, b3 << 2, (b4 & 0b1111) << 8, 1);
    070        this.hasAlpha = (b4 & 0b0001_0000) != 0;
    071        this.versionNumber = b4 >> 5;
    072
    073        if (versionNumber != 0) {
    074            throw new ImagingException("VP8L version should be 0");
    075        }
    076    }
    077
    078    @Override
    079    public void dump(final PrintWriter pw, final int offset) throws ImagingException, IOException {
    080        super.dump(pw, offset);
    081        pw.println("  Version Number: " + getVersionNumber());
    082        pw.println("  Image Width: " + getImageWidth());
    083        pw.println("  Image Height: " + getImageHeight());
    084        pw.println("  Alpha: " + hasAlpha());
    085    }
    086
    087    /**
    088     * @return the image height.
    089     */
    090    public int getImageHeight() {
    091        return imageHeight;
    092    }
    093
    094    /**
    095     * @return the image width.
    096     */
    097    public int getImageWidth() {
    098        return imageWidth;
    099    }
    100
    101    /**
    102     * @return the version number.
    103     */
    104    public int getVersionNumber() {
    105        return versionNumber;
    106    }
    107
    108    /**
    109     * @return whether the image has an alpha channel or not.
    110     */
    111    public boolean hasAlpha() {
    112        return hasAlpha;
    113    }
    114}