1 /**
2 * Copyright 2011, Aiki IT, FotoRenamer
3 * <p/>
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 * <p/>
8 * http://www.apache.org/licenses/LICENSE-2.0
9 * <p/>
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package de.aikiit.fotorenamer.image;
17
18 import com.google.common.base.Strings;
19 import org.apache.commons.imaging.ImageReadException;
20 import org.apache.commons.imaging.Imaging;
21 import org.apache.commons.imaging.common.ImageMetadata;
22 import org.apache.commons.imaging.formats.jpeg.JpegImageMetadata;
23 import org.apache.commons.imaging.formats.tiff.TiffField;
24 import org.apache.commons.imaging.formats.tiff.constants.ExifTagConstants;
25 import org.apache.commons.imaging.formats.tiff.taginfos.TagInfo;
26 import org.apache.log4j.Logger;
27
28 import java.io.File;
29 import java.io.IOException;
30
31 /**
32 * Helper class to extract metadata from given images. This class uses Apache
33 * Sanslean to perform the metadata extraction itself.
34 */
35 final class MetaDataExtractor {
36 /**
37 * This class' logger.
38 */
39 private static final Logger LOG = Logger.getLogger(MetaDataExtractor.class);
40
41 /**
42 * Constant for an empty string.
43 */
44 private static final String EMPTY_STRING = "";
45
46 /**
47 * Constant for a blank character.
48 */
49 private static final String SPACE = " ";
50
51 /**
52 * Constant for an underscore character.
53 */
54 private static final String UNDERSCORE = "_";
55
56 /**
57 * Constant for a colon.
58 */
59 private static final String COLON = ":";
60
61 /**
62 * Constant for an apostrophe.
63 */
64 private static final String APOSTROPHE = "'";
65
66 /**
67 * Constant to describe a valid length of an EXIF date (currently 21).
68 */
69 private static final int VALID_EXIF_DATE_LENGTH = 21;
70
71 /**
72 * Constructor is not visible to avoid instantiation.
73 */
74 private MetaDataExtractor() {
75 // prevent instantiation of this utility class
76 }
77
78 /**
79 * Returns the requested tag as String from the image file.
80 *
81 * @param image Image file to extract Metadata from.
82 * @param tag Tag to extract from the given file, @see TiffConstants
83 * @return Returns exif tag value, in case of any errors the value is an
84 * empty String.
85 * @throws IOException if file cannot be accessed.
86 * @throws ImageReadException if an error occurred during image processing.
87 */
88 public static String getExifMetadata(final File image,
89 final TagInfo tag)
90 throws IOException, ImageReadException {
91 assert image != null : "Parameter image must not be null";
92 assert tag != null : "Parameter tag must not be null";
93
94 String result = EMPTY_STRING;
95 ImageMetadata metadata = Imaging.getMetadata(image);
96
97 if (metadata instanceof JpegImageMetadata) {
98 JpegImageMetadata jpegMetadata = (JpegImageMetadata) metadata;
99 TiffField field = jpegMetadata.findEXIFValueWithExactMatch(tag);
100 if (field != null) {
101 result = field.getValueDescription();
102 LOG.info("extraction of " + tag.getDescription()
103 + " yields " + result);
104 }
105 }
106 return result == null ? EMPTY_STRING : result;
107 }
108
109 /**
110 * Helper to extract the date this image was created to be used during the
111 * renaming process.
112 * <br>
113 * In the EXIF standard itself the following convention for dates as is
114 * defined: <i> D. Other Tags DateTime The date and time of image creation.
115 * In this standard it is the date and time the file was changed. The format
116 * is "YYYY:MM:DD HH:MM:SS" with time shown in 24-hour format, and the date
117 * and time separated by one blank character [20.H]. When the date and time
118 * are unknown, all the character spaces except colons (":") may be filled
119 * with blank characters, or else the Interoperability field may be filled
120 * with blank characters. The character string length is 20 bytes including
121 * NULL for termination. When the field is left blank, it is treated as
122 * unknown. Tag = 306 (132.H) Type = ASCII Count = 20 Default = none </i>
123 * <p>
124 * If the extracted date value is empty - no new file name is generated.
125 *
126 * @param image Image to extract metadata from.
127 * @return the date this image was created if found, format is
128 * @throws ImageReadException If image cannot be read.
129 * @throws IOException If an error occurs when accessing the image's
130 * metadata.
131 * @see <a href="http://www.exif.org/samples/canon-ixus.html">Canon EXIF
132 * example page</a>
133 * @see <a href="http://www.exif.org/specifications.html">EXIF
134 * specifications</a>
135 * @see <a href="http://www.exif.org/Exif2-2.PDF">EXIF2-2.pdf
136 * specification</a>
137 */
138 public static String generateCreationDateInCorrectFormat(final File image)
139 throws ImageReadException, IOException {
140
141 String dateValue =
142 getExifMetadata(image, ExifTagConstants.EXIF_TAG_DATE_TIME_ORIGINAL);
143
144 LOG.info("EXIF date value is: " + dateValue);
145
146 // Invalid length of EXIF metadata, not complying to the standard.
147 if (Strings.isNullOrEmpty(dateValue) || dateValue.length() != VALID_EXIF_DATE_LENGTH) {
148 LOG.info("No valid creation date extracted from file " + image);
149 return EMPTY_STRING;
150 }
151
152 // Date parsing with apache.DateUtils or JDK-DateFormats
153 // does not work due to '-signs in the date string
154 // (unparseable pattern is "'yyyy:MM:dd HH:mm:ss'")
155 // replace special characters to extract digits only
156 dateValue = dateValue.replaceAll(APOSTROPHE, EMPTY_STRING);
157 dateValue = dateValue.replaceAll(COLON, EMPTY_STRING);
158 dateValue = dateValue.replaceAll(SPACE, UNDERSCORE);
159 dateValue += UNDERSCORE;
160 //convert '2011:01:30 13:11:02' to "yyyyMMdd_HHmm_"+fileName
161 dateValue += image.getName();
162
163 LOG.info("Target filename is: " + dateValue);
164 return dateValue;
165 }
166 }