    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.jpeg.segments;
    018
    019import static org.apache.commons.imaging.common.BinaryFunctions.read2Bytes;
    020import static org.apache.commons.imaging.common.BinaryFunctions.readByte;
    021import static org.apache.commons.imaging.common.BinaryFunctions.readBytes;
    022import static org.apache.commons.imaging.common.BinaryFunctions.skipBytes;
    023
    024import java.io.ByteArrayInputStream;
    025import java.io.IOException;
    026import java.io.InputStream;
    027
    028import org.apache.commons.imaging.ImageReadException;
    029import org.apache.commons.imaging.formats.jpeg.JpegConstants;
    030
    031public class JfifSegment extends Segment {
    032    public final int jfifMajorVersion;
    033    public final int jfifMinorVersion;
    034    public final int densityUnits;
    035    public final int xDensity;
    036    public final int yDensity;
    037
    038    public final int xThumbnail;
    039    public final int yThumbnail;
    040    public final int thumbnailSize;
    041
    042    @Override
    043    public String getDescription() {
    044        return "JFIF (" + getSegmentType() + ")";
    045    }
    046
    047    public JfifSegment(final int marker, final byte[] segmentData)
    048            throws ImageReadException, IOException {
    049        this(marker, segmentData.length, new ByteArrayInputStream(segmentData));
    050    }
    051
    052    public JfifSegment(final int marker, final int markerLength, final InputStream is)
    053            throws ImageReadException, IOException {
    054        super(marker, markerLength);
    055
    056        final byte[] signature = readBytes(is, JpegConstants.JFIF0_SIGNATURE.size());
    057        if (!JpegConstants.JFIF0_SIGNATURE.equals(signature)
    058                && !JpegConstants.JFIF0_SIGNATURE_ALTERNATIVE.equals(signature)) {
    059            throw new ImageReadException(
    060                    "Not a Valid JPEG File: missing JFIF string");
    061        }
    062
    063        jfifMajorVersion = readByte("JFIF_major_version", is,
    064                "Not a Valid JPEG File");
    065        jfifMinorVersion = readByte("JFIF_minor_version", is,
    066                "Not a Valid JPEG File");
    067        densityUnits = readByte("density_units", is, "Not a Valid JPEG File");
    068        xDensity = read2Bytes("x_density", is, "Not a Valid JPEG File", getByteOrder());
    069        yDensity = read2Bytes("y_density", is, "Not a Valid JPEG File", getByteOrder());
    070
    071        xThumbnail = readByte("x_thumbnail", is, "Not a Valid JPEG File");
    072        yThumbnail = readByte("y_thumbnail", is, "Not a Valid JPEG File");
    073        thumbnailSize = xThumbnail * yThumbnail;
    074        if (thumbnailSize > 0) {
    075            skipBytes(is, thumbnailSize,
    076                    "Not a Valid JPEG File: missing thumbnail");
    077
    078        }
    079    }
    080
    081}