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
27extern "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 */
35typedef struct _ExifEntry        ExifEntry;
36typedef 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 */
43struct _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 */
80ExifEntry  *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 */
90ExifEntry  *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 */
98void        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 */
105void        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 */
114void        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 */
125void        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 */
140void        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 */
163const 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 */
172void        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