1 | /*
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2 | * Copyright 2002-2015 Drew Noakes
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | * More information about this project is available at:
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17 | *
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18 | * https://drewnoakes.com/code/exif/
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19 | * https://github.com/drewnoakes/metadata-extractor
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20 | */
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21 | package com.drew.metadata.exif;
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22 |
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23 | import com.drew.imaging.jpeg.JpegSegmentMetadataReader;
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24 | import com.drew.imaging.jpeg.JpegSegmentType;
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25 | import com.drew.imaging.tiff.TiffProcessingException;
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26 | import com.drew.imaging.tiff.TiffReader;
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27 | import com.drew.lang.ByteArrayReader;
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28 | import com.drew.lang.annotations.NotNull;
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29 | import com.drew.metadata.Metadata;
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30 |
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31 | import java.io.IOException;
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32 | import java.util.Arrays;
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33 |
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34 | /**
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35 | * Decodes Exif binary data, populating a {@link Metadata} object with tag values in {@link ExifSubIFDDirectory},
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36 | * {@link ExifThumbnailDirectory}, {@link ExifInteropDirectory}, {@link GpsDirectory} and one of the many camera
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37 | * makernote directories.
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38 | *
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39 | * @author Drew Noakes https://drewnoakes.com
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40 | */
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41 | public class ExifReader implements JpegSegmentMetadataReader
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42 | {
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43 | /**
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44 | * The offset at which the TIFF data actually starts. This may be necessary when, for example, processing
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45 | * JPEG Exif data from APP0 which has a 6-byte preamble before starting the TIFF data.
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46 | */
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47 | private static final String JPEG_EXIF_SEGMENT_PREAMBLE = "Exif\0\0";
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48 |
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49 | private boolean _storeThumbnailBytes = true;
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50 |
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51 | public boolean isStoreThumbnailBytes()
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52 | {
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53 | return _storeThumbnailBytes;
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54 | }
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55 |
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56 | public void setStoreThumbnailBytes(boolean storeThumbnailBytes)
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57 | {
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58 | _storeThumbnailBytes = storeThumbnailBytes;
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59 | }
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60 |
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61 | @NotNull
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62 | public Iterable<JpegSegmentType> getSegmentTypes()
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63 | {
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64 | return Arrays.asList(JpegSegmentType.APP1);
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65 | }
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66 |
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67 | public boolean canProcess(@NotNull final byte[] segmentBytes, @NotNull final JpegSegmentType segmentType)
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68 | {
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69 | return segmentBytes.length >= JPEG_EXIF_SEGMENT_PREAMBLE.length() && new String(segmentBytes, 0, JPEG_EXIF_SEGMENT_PREAMBLE.length()).equalsIgnoreCase(JPEG_EXIF_SEGMENT_PREAMBLE);
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70 | }
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71 |
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72 | public void extract(@NotNull final byte[] segmentBytes, @NotNull final Metadata metadata, @NotNull final JpegSegmentType segmentType)
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73 | {
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74 | if (segmentBytes == null)
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75 | throw new NullPointerException("segmentBytes cannot be null");
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76 | if (metadata == null)
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77 | throw new NullPointerException("metadata cannot be null");
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78 | if (segmentType == null)
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79 | throw new NullPointerException("segmentType cannot be null");
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80 |
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81 | try {
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82 | ByteArrayReader reader = new ByteArrayReader(segmentBytes);
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83 |
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84 | //
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85 | // Check for the header preamble
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86 | //
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87 | try {
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88 | if (!reader.getString(0, JPEG_EXIF_SEGMENT_PREAMBLE.length()).equals(JPEG_EXIF_SEGMENT_PREAMBLE)) {
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89 | // TODO what do to with this error state?
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90 | System.err.println("Invalid JPEG Exif segment preamble");
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91 | return;
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92 | }
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93 | } catch (IOException e) {
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94 | // TODO what do to with this error state?
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95 | e.printStackTrace(System.err);
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96 | return;
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97 | }
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98 |
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99 | //
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100 | // Read the TIFF-formatted Exif data
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101 | //
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102 | new TiffReader().processTiff(
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103 | reader,
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104 | new ExifTiffHandler(metadata, _storeThumbnailBytes),
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105 | JPEG_EXIF_SEGMENT_PREAMBLE.length()
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106 | );
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107 |
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108 | } catch (TiffProcessingException e) {
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109 | // TODO what do to with this error state?
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110 | e.printStackTrace(System.err);
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111 | } catch (IOException e) {
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112 | // TODO what do to with this error state?
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113 | e.printStackTrace(System.err);
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114 | }
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115 | }
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116 | }
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