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/*
* Copyright 2002-2017 Drew Noakes
*
* Licensed 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.
*
* More information about this project is available at:
*
* https://drewnoakes.com/code/exif/
* https://github.com/drewnoakes/metadata-extractor
*/
package com.drew.metadata.jfxx;
import com.drew.imaging.jpeg.JpegSegmentMetadataReader;
import com.drew.imaging.jpeg.JpegSegmentType;
import com.drew.lang.ByteArrayReader;
import com.drew.lang.RandomAccessReader;
import com.drew.lang.annotations.NotNull;
import com.drew.metadata.Metadata;
import com.drew.metadata.MetadataReader;
import java.io.IOException;
import java.util.Collections;
/**
* Reader for JFXX (JFIF extensions) data, found in the APP0 JPEG segment.
*
* <ul>
* <li>http://en.wikipedia.org/wiki/JPEG_File_Interchange_Format</li>
* <li>http://www.w3.org/Graphics/JPEG/jfif3.pdf</li>
* </ul>
*
* @author Drew Noakes
*/
public class JfxxReader implements JpegSegmentMetadataReader, MetadataReader
{
public static final String PREAMBLE = "JFXX";
@NotNull
public Iterable<JpegSegmentType> getSegmentTypes()
{
return Collections.singletonList(JpegSegmentType.APP0);
}
public void readJpegSegments(@NotNull Iterable<byte[]> segments, @NotNull Metadata metadata, @NotNull JpegSegmentType segmentType)
{
for (byte[] segmentBytes : segments) {
// Skip segments not starting with the required header
if (segmentBytes.length >= PREAMBLE.length() && PREAMBLE.equals(new String(segmentBytes, 0, PREAMBLE.length())))
extract(new ByteArrayReader(segmentBytes), metadata);
}
}
/**
* Performs the JFXX data extraction, adding found values to the specified
* instance of {@link Metadata}.
*/
public void extract(@NotNull final RandomAccessReader reader, @NotNull final Metadata metadata)
{
JfxxDirectory directory = new JfxxDirectory();
metadata.addDirectory(directory);
try {
// For JFXX, the tag number is also the offset into the segment
directory.setInt(JfxxDirectory.TAG_EXTENSION_CODE, reader.getUInt8(JfxxDirectory.TAG_EXTENSION_CODE));
} catch (IOException me) {
directory.addError(me.getMessage());
}
}
}
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