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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.exif;
import com.drew.imaging.jpeg.JpegSegmentMetadataReader;
import com.drew.imaging.jpeg.JpegSegmentType;
import com.drew.imaging.tiff.TiffProcessingException;
import com.drew.imaging.tiff.TiffReader;
import com.drew.lang.ByteArrayReader;
import com.drew.lang.RandomAccessReader;
import com.drew.lang.annotations.NotNull;
import com.drew.lang.annotations.Nullable;
import com.drew.metadata.Directory;
import com.drew.metadata.Metadata;
import java.io.IOException;
import java.util.Collections;
/**
* Decodes Exif binary data, populating a {@link Metadata} object with tag values in {@link ExifSubIFDDirectory},
* {@link ExifThumbnailDirectory}, {@link ExifInteropDirectory}, {@link GpsDirectory} and one of the many camera
* makernote directories.
*
* @author Drew Noakes https://drewnoakes.com
*/
@SuppressWarnings("WeakerAccess")
public class ExifReader implements JpegSegmentMetadataReader
{
/** Exif data stored in JPEG files' APP1 segment are preceded by this six character preamble. */
public static final String JPEG_SEGMENT_PREAMBLE = "Exif\0\0";
@NotNull
public Iterable<JpegSegmentType> getSegmentTypes()
{
return Collections.singletonList(JpegSegmentType.APP1);
}
public void readJpegSegments(@NotNull final Iterable<byte[]> segments, @NotNull final Metadata metadata, @NotNull final JpegSegmentType segmentType)
{
assert(segmentType == JpegSegmentType.APP1);
for (byte[] segmentBytes : segments) {
// Filter any segments containing unexpected preambles
if (segmentBytes.length < JPEG_SEGMENT_PREAMBLE.length() || !new String(segmentBytes, 0, JPEG_SEGMENT_PREAMBLE.length()).equals(JPEG_SEGMENT_PREAMBLE))
continue;
extract(new ByteArrayReader(segmentBytes), metadata, JPEG_SEGMENT_PREAMBLE.length());
}
}
/** Reads TIFF formatted Exif data from start of the specified {@link RandomAccessReader}. */
public void extract(@NotNull final RandomAccessReader reader, @NotNull final Metadata metadata)
{
extract(reader, metadata, 0);
}
/** Reads TIFF formatted Exif data a specified offset within a {@link RandomAccessReader}. */
public void extract(@NotNull final RandomAccessReader reader, @NotNull final Metadata metadata, int readerOffset)
{
extract(reader, metadata, readerOffset, null);
}
/** Reads TIFF formatted Exif data at a specified offset within a {@link RandomAccessReader}. */
public void extract(@NotNull final RandomAccessReader reader, @NotNull final Metadata metadata, int readerOffset, @Nullable Directory parentDirectory)
{
ExifTiffHandler exifTiffHandler = new ExifTiffHandler(metadata, parentDirectory);
try {
// Read the TIFF-formatted Exif data
new TiffReader().processTiff(
reader,
exifTiffHandler,
readerOffset
);
} catch (TiffProcessingException e) {
exifTiffHandler.error("Exception processing TIFF data: " + e.getMessage());
// TODO what do to with this error state?
e.printStackTrace(System.err);
} catch (IOException e) {
exifTiffHandler.error("Exception processing TIFF data: " + e.getMessage());
// TODO what do to with this error state?
e.printStackTrace(System.err);
}
}
}
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