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1 /*! \file exif-entry.h
2  *  \brief Handling EXIF entries
3  */
4 /*
5  * Copyright (c) 2001 Lutz Mueller <lutz@users.sourceforge.net>
6  *
7  * This library is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2 of the License, or (at your option) any later version.
11  *
12  * This library is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this library; if not, write to the
19  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
20  * Boston, MA  02110-1301  USA.
21  */
22 
23 #ifndef __EXIF_ENTRY_H__
24 #define __EXIF_ENTRY_H__
25 
26 #ifdef __cplusplus
27 extern "C" {
28 #endif /* __cplusplus */
29 
30 /*! Data found in one EXIF tag.
31  * The #exif_entry_get_value function can provide access to the
32  * formatted contents, or the struct members can be used directly to
33  * access the raw contents.
34  */
35 typedef struct _ExifEntry        ExifEntry;
36 typedef struct _ExifEntryPrivate ExifEntryPrivate;
37 
38 #include <libexif/exif-content.h>
39 #include <libexif/exif-format.h>
40 #include <libexif/exif-mem.h>
41 
42 /*! Data found in one EXIF tag */
43 struct _ExifEntry {
44 	/*! EXIF tag for this entry */
45         ExifTag tag;
46 
47 	/*! Type of data in this entry */
48         ExifFormat format;
49 
50 	/*! Number of elements in the array, if this is an array entry.
51 	 * Contains 1 for non-array data types. */
52         unsigned long components;
53 
54 	/*! Pointer to the raw EXIF data for this entry. It is allocated
55 	 * by #exif_entry_initialize and is NULL beforehand. Data contained
56 	 * here may be manipulated using the functions in exif-utils.h */
57         unsigned char *data;
58 
59 	/*! Number of bytes in the buffer at \c data. This must be no less
60 	 * than exif_format_get_size(format)*components */
61         unsigned int size;
62 
63 	/*! #ExifContent containing this entry.
64 	 * \see exif_entry_get_ifd */
65 	ExifContent *parent;
66 
67 	/*! Internal data to be used by libexif itself */
68 	ExifEntryPrivate *priv;
69 };
70 
71 /* Lifecycle */
72 
73 /*! Reserve memory for and initialize a new #ExifEntry.
74  * No memory is allocated for the \c data element of the returned #ExifEntry.
75  *
76  * \return new allocated #ExifEntry, or NULL on error
77  *
78  * \see exif_entry_new_mem, exif_entry_unref
79  */
80 ExifEntry  *exif_entry_new     (void);
81 
82 /*! Reserve memory for and initialize new #ExifEntry using the specified
83  * memory allocator.
84  * No memory is allocated for the \c data element of the returned #ExifEntry.
85  *
86  * \return new allocated #ExifEntry, or NULL on error
87  *
88  * \see exif_entry_new, exif_entry_unref
89  */
90 ExifEntry  *exif_entry_new_mem (ExifMem *);
91 
92 /*! Increase reference counter for #ExifEntry.
93  *
94  * \param[in] entry #ExifEntry
95  *
96  * \see exif_entry_unref
97  */
98 void        exif_entry_ref     (ExifEntry *entry);
99 
100 /*! Decrease reference counter for #ExifEntry.
101  * When the reference count drops to zero, free the entry.
102  *
103  * \param[in] entry #ExifEntry
104  */
105 void        exif_entry_unref   (ExifEntry *entry);
106 
107 /*! Actually free the #ExifEntry.
108  *
109  * \deprecated Should not be called directly. Use #exif_entry_ref and
110  *             #exif_entry_unref instead.
111  *
112  * \param[in] entry EXIF entry
113  */
114 void        exif_entry_free  (ExifEntry *entry);
115 
116 /*! Initialize an empty #ExifEntry with default data in the correct format
117  * for the given tag. If the entry is already initialized, this function
118  * does nothing.
119  * This call allocates memory for the \c data element of the given #ExifEntry.
120  * That memory is freed at the same time as the #ExifEntry.
121  *
122  * \param[out] e entry to initialize
123  * \param[in] tag tag number to initialize as
124  */
125 void        exif_entry_initialize (ExifEntry *e, ExifTag tag);
126 
127 /*! Fix the type or format of the given EXIF entry to bring it into spec.
128  * If the data for this EXIF tag is in of the wrong type or is in an invalid
129  * format according to the EXIF specification, then it is converted to make it
130  * valid. This may involve, for example, converting an EXIF_FORMAT_LONG into a
131  * EXIF_FORMAT_SHORT. If the tag is unknown, its value is untouched.
132  *
133  * \note Unfortunately, some conversions are to a type with a more restricted
134  * range, which could have the side effect that the converted data becomes
135  * invalid. This is unlikely as the range of each tag in the standard is
136  * designed to encompass all likely data.
137  *
138  * \param[in,out] entry EXIF entry
139  */
140 void        exif_entry_fix        (ExifEntry *entry);
141 
142 
143 /* For your convenience */
144 
145 /*! Return a localized textual representation of the value of the EXIF entry.
146  * This is meant for display to the user. The format of each tag is subject
147  * to change between locales and in newer versions of libexif.  Users who
148  * require the tag data in an unambiguous form should access the data members
149  * of the #ExifEntry structure directly.
150  *
151  * \warning The character set of the returned string may be in
152  *          the encoding of the current locale or the native encoding
153  *          of the camera.
154  * \bug     The EXIF_TAG_XP_* tags are currently always returned in UTF-8,
155  *          regardless of locale, and code points above U+FFFF are not
156  *          supported.
157  *
158  * \param[in] entry EXIF entry
159  * \param[out] val buffer in which to store value
160  * \param[in] maxlen length of the buffer val
161  * \return val pointer
162  */
163 const char *exif_entry_get_value (ExifEntry *entry, char *val,
164 				  unsigned int maxlen);
165 
166 /*! Dump text representation of #ExifEntry to stdout.
167  * This is intended for diagnostic purposes only.
168  *
169  * \param[in] entry EXIF tag data
170  * \param[in] indent how many levels deep to indent the data
171  */
172 void        exif_entry_dump      (ExifEntry *entry, unsigned int indent);
173 
174 /*! Return the IFD number of the given #ExifEntry
175  *
176  * \param[in] e an #ExifEntry*
177  * \return #ExifIfd, or #EXIF_IFD_COUNT on error
178  */
179 #define exif_entry_get_ifd(e) ((e)?exif_content_get_ifd((e)->parent):EXIF_IFD_COUNT)
180 
181 #ifdef __cplusplus
182 }
183 #endif /* __cplusplus */
184 
185 #endif /* __EXIF_ENTRY_H__ */
186