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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.jpeg;
import com.drew.imaging.jpeg.JpegSegmentMetadataReader;
import com.drew.imaging.jpeg.JpegSegmentType;
import com.drew.lang.SequentialByteArrayReader;
import com.drew.lang.SequentialReader;
import com.drew.lang.annotations.NotNull;
import com.drew.metadata.ErrorDirectory;
import com.drew.metadata.Metadata;
import java.io.IOException;
import java.util.Collections;
/**
* Decodes JPEG DNL data, adjusting the image height with information missing from the JPEG SOFx segment.
*
* @author Nadahar
*/
public class JpegDnlReader implements JpegSegmentMetadataReader
{
@NotNull
public Iterable<JpegSegmentType> getSegmentTypes()
{
return Collections.singletonList(JpegSegmentType.DNL);
}
public void readJpegSegments(@NotNull Iterable<byte[]> segments, @NotNull Metadata metadata, @NotNull JpegSegmentType segmentType)
{
for (byte[] segmentBytes : segments) {
extract(segmentBytes, metadata, segmentType);
}
}
public void extract(byte[] segmentBytes, Metadata metadata, JpegSegmentType segmentType)
{
JpegDirectory directory = metadata.getFirstDirectoryOfType(JpegDirectory.class);
if (directory == null) {
ErrorDirectory errorDirectory = new ErrorDirectory();
metadata.addDirectory(errorDirectory);
errorDirectory.addError("DNL segment found without SOFx - illegal JPEG format");
return;
}
SequentialReader reader = new SequentialByteArrayReader(segmentBytes);
try {
// Only set height from DNL if it's not already defined
Integer i = directory.getInteger(JpegDirectory.TAG_IMAGE_HEIGHT);
if (i == null || i == 0) {
directory.setInt(JpegDirectory.TAG_IMAGE_HEIGHT, reader.getUInt16());
}
} catch (IOException ex) {
directory.addError(ex.getMessage());
}
}
}
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