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libexif
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exif-entry.h
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/*! \file exif-entry.h * \brief Handling EXIF entries */ /* * Copyright (c) 2001 Lutz Mueller <lutz@users.sourceforge.net> * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, * Boston, MA 02110-1301 USA. */ #ifndef LIBEXIF_EXIF_ENTRY_H #define LIBEXIF_EXIF_ENTRY_H #ifdef __cplusplus extern "C" { #endif /* __cplusplus */ /*! Data found in one EXIF tag. * The #exif_entry_get_value function can provide access to the * formatted contents, or the struct members can be used directly to * access the raw contents. */ typedef struct _ExifEntry ExifEntry; typedef struct _ExifEntryPrivate ExifEntryPrivate; #include <libexif/exif-content.h> #include <libexif/exif-format.h> #include <libexif/exif-mem.h> /*! Data found in one EXIF tag */ struct _ExifEntry { /*! EXIF tag for this entry */ ExifTag tag; /*! Type of data in this entry */ ExifFormat format; /*! Number of elements in the array, if this is an array entry. * Contains 1 for non-array data types. */ unsigned long components; /*! Pointer to the raw EXIF data for this entry. It is allocated * by #exif_entry_initialize and is NULL beforehand. Data contained * here may be manipulated using the functions in exif-utils.h */ unsigned char *data; /*! Number of bytes in the buffer at \c data. This must be no less * than exif_format_get_size(format)*components */ unsigned int size; /*! #ExifContent containing this entry. * \see exif_entry_get_ifd */ ExifContent *parent; /*! Internal data to be used by libexif itself */ ExifEntryPrivate *priv; }; /* Lifecycle */ /*! Reserve memory for and initialize a new #ExifEntry. * No memory is allocated for the \c data element of the returned #ExifEntry. * * \return new allocated #ExifEntry, or NULL on error * * \see exif_entry_new_mem, exif_entry_unref */ ExifEntry *exif_entry_new (void); /*! Reserve memory for and initialize new #ExifEntry using the specified * memory allocator. * No memory is allocated for the \c data element of the returned #ExifEntry. * * \return new allocated #ExifEntry, or NULL on error * * \see exif_entry_new, exif_entry_unref */ ExifEntry *exif_entry_new_mem (ExifMem *); /*! Increase reference counter for #ExifEntry. * * \param[in] entry #ExifEntry * * \see exif_entry_unref */ void exif_entry_ref (ExifEntry *entry); /*! Decrease reference counter for #ExifEntry. * When the reference count drops to zero, free the entry. * * \param[in] entry #ExifEntry */ void exif_entry_unref (ExifEntry *entry); /*! Actually free the #ExifEntry. * * \deprecated Should not be called directly. Use #exif_entry_ref and * #exif_entry_unref instead. * * \param[in] entry EXIF entry */ void exif_entry_free (ExifEntry *entry); /*! Initialize an empty #ExifEntry with default data in the correct format * for the given tag. If the entry is already initialized, this function * does nothing. * This call allocates memory for the \c data element of the given #ExifEntry. * That memory is freed at the same time as the #ExifEntry. * * \param[out] e entry to initialize * \param[in] tag tag number to initialize as */ void exif_entry_initialize (ExifEntry *e, ExifTag tag); /*! Fix the type or format of the given EXIF entry to bring it into spec. * If the data for this EXIF tag is in of the wrong type or is in an invalid * format according to the EXIF specification, then it is converted to make it * valid. This may involve, for example, converting an EXIF_FORMAT_LONG into a * EXIF_FORMAT_SHORT. If the tag is unknown, its value is untouched. * * \note Unfortunately, some conversions are to a type with a more restricted * range, which could have the side effect that the converted data becomes * invalid. This is unlikely as the range of each tag in the standard is * designed to encompass all likely data. * * \param[in,out] entry EXIF entry */ void exif_entry_fix (ExifEntry *entry); /* For your convenience */ /*! Return a localized textual representation of the value of the EXIF entry. * This is meant for display to the user. The format of each tag is subject * to change between locales and in newer versions of libexif. Users who * require the tag data in an unambiguous form should access the data members * of the #ExifEntry structure directly. * * \warning The character set of the returned string may be in * the encoding of the current locale or the native encoding * of the camera. * \bug The EXIF_TAG_XP_* tags are currently always returned in UTF-8, * regardless of locale, and code points above U+FFFF are not * supported. * * \param[in] entry EXIF entry * \param[out] val buffer in which to store value; if entry is valid and * maxlen > 0 then this string will be NUL-terminated * \param[in] maxlen length of the buffer val * \return val pointer */ const char *exif_entry_get_value (ExifEntry *entry, char *val, unsigned int maxlen); /*! Dump text representation of #ExifEntry to stdout. * This is intended for diagnostic purposes only. * * \param[in] entry EXIF tag data * \param[in] indent how many levels deep to indent the data */ void exif_entry_dump (ExifEntry *entry, unsigned int indent); /*! Return the IFD number of the given #ExifEntry * * \param[in] e an #ExifEntry* * \return #ExifIfd, or #EXIF_IFD_COUNT on error */ #define exif_entry_get_ifd(e) ((e)?exif_content_get_ifd((e)->parent):EXIF_IFD_COUNT) #ifdef __cplusplus } #endif /* __cplusplus */ #endif /* !defined(LIBEXIF_EXIF_ENTRY_H) */