gaiaexif.h File Reference

EXIF/image: supporting functions and constants. More...

Go to the source code of this file.

Data Structures
struct	gaiaExifTagStruct
	Container for an EXIF tag. More...
struct	gaiaExifTagListStruct
	Container for a list of EXIF tags. More...

Macros
#define	GAIA_HEX_BLOB   0
	generic hexadecimal BLOB
#define	GAIA_GIF_BLOB   1
	this BLOB does actually contain a GIF image
#define	GAIA_PNG_BLOB   2
	this BLOB does actually containt a PNG image
#define	GAIA_JPEG_BLOB   3
	this BLOB does actually contain a generic JPEG image
#define	GAIA_EXIF_BLOB   4
	this BLOB does actually contain a JPEG-EXIF image
#define	GAIA_EXIF_GPS_BLOB   5
	this BLOB does actually contain a JPEG-EXIF image including GPS data
#define	GAIA_ZIP_BLOB   6
	this BLOB does actually contain a ZIP compressed file
#define	GAIA_PDF_BLOB   7
	this BLOB does actually contain a PDF document
#define	GAIA_GEOMETRY_BLOB   8
	this BLOB does actually contain a SpatiaLite Geometry
#define	GAIA_TIFF_BLOB   9
	this BLOB does actually contain a TIFF image
#define	GAIA_WEBP_BLOB   10
	this BLOB does actually contain a WebP image
#define	GAIA_EXIF_NONE   0
	unrecognized EXIF value
#define	GAIA_EXIF_BYTE   1
	EXIF value of the BYTE type.
#define	GAIA_EXIF_SHORT   2
	EXIF value of the SHORT type.
#define	GAIA_EXIF_STRING   3
	EXIF value of the STRING type.
#define	GAIA_EXIF_LONG   4
	EXIF value of the LONG type.
#define	GAIA_EXIF_RATIONAL   5
	EXIF value of the RATIONAL type.
#define	GAIA_EXIF_SLONG   9
	EXIF value of the SLONG type.
#define	GAIA_EXIF_SRATIONAL   10
	EXIF value of the SRATIONAL type.

Typedefs
typedef struct gaiaExifTagStruct	gaiaExifTag
	Container for an EXIF tag.
typedef gaiaExifTag *	gaiaExifTagPtr
	Typedef for EXIF tag structure.
typedef struct gaiaExifTagListStruct	gaiaExifTagList
	Container for a list of EXIF tags.
typedef gaiaExifTagList *	gaiaExifTagListPtr
	Typedef for EXIF tag structure.

Functions
GAIAEXIF_DECLARE gaiaExifTagListPtr	gaiaGetExifTags (const unsigned char *blob, int size)
	Creates a list of EXIF tags by parsing a BLOB of the JPEG-EXIF type.
GAIAEXIF_DECLARE void	gaiaExifTagsFree (gaiaExifTagListPtr tag_list)
	Destroy a list of EXIF tags.
GAIAEXIF_DECLARE int	gaiaGetExifTagsCount (gaiaExifTagListPtr tag_list)
	Return the total number of EXIF tags into the list.
GAIAEXIF_DECLARE gaiaExifTagPtr	gaiaGetExifTagByPos (gaiaExifTagListPtr tag_list, const int pos)
	Retrieves an EXIF tag by its relative position into the list.
GAIAEXIF_DECLARE gaiaExifTagPtr	gaiaGetExifTagById (const gaiaExifTagListPtr tag_list, const unsigned short tag_id)
	Retrieves an EXIF tag by its Tag ID.
GAIAEXIF_DECLARE gaiaExifTagPtr	gaiaGetExifGpsTagById (const gaiaExifTagListPtr tag_list, const unsigned short tag_id)
	Retrieves an EXIF-GPS tag by its Tag ID.
GAIAEXIF_DECLARE gaiaExifTagPtr	gaiaGetExifTagByName (const gaiaExifTagListPtr tag_list, const char *tag_name)
	Retrieves an EXIF tag by its name.
GAIAEXIF_DECLARE unsigned short	gaiaExifTagGetId (const gaiaExifTagPtr tag)
	Return the Tag ID from an EXIF tag.
GAIAEXIF_DECLARE void	gaiaExifTagGetName (const gaiaExifTagPtr tag, char *tag_name, int len)
	Return the Tag Name from an EXIF tag.
GAIAEXIF_DECLARE int	gaiaIsExifGpsTag (const gaiaExifTagPtr tag)
	Checks if an EXIF tag actually is an EXIF-GPS tag.
GAIAEXIF_DECLARE unsigned short	gaiaExifTagGetValueType (const gaiaExifTagPtr tag)
	Return the value type for an EXIF tag.
GAIAEXIF_DECLARE unsigned short	gaiaExifTagGetNumValues (const gaiaExifTagPtr tag)
	Return the total count of values from an EXIF tag.
GAIAEXIF_DECLARE unsigned char	gaiaExifTagGetByteValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a BYTE value from an EXIF tag.
GAIAEXIF_DECLARE void	gaiaExifTagGetStringValue (const gaiaExifTagPtr tag, char *str, int len, int *ok)
	Return a STRING value from an EXIF tag.
GAIAEXIF_DECLARE unsigned short	gaiaExifTagGetShortValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a SHORT value from an EXIF tag.
GAIAEXIF_DECLARE unsigned int	gaiaExifTagGetLongValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a LONG value from an EXIF tag.
GAIAEXIF_DECLARE unsigned int	gaiaExifTagGetRational1Value (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a RATIONAL [numerator] value from an EXIF tag.
GAIAEXIF_DECLARE unsigned int	gaiaExifTagGetRational2Value (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a RATIONAL [denominator] value from an EXIF tag.
GAIAEXIF_DECLARE double	gaiaExifTagGetRationalValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a RATIONAL value from an EXIF tag.
GAIAEXIF_DECLARE short	gaiaExifTagGetSignedShortValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a Signed SHORT value from an EXIF tag.
GAIAEXIF_DECLARE int	gaiaExifTagGetSignedLongValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a Signed LONG value from an EXIF tag.
GAIAEXIF_DECLARE int	gaiaExifTagGetSignedRational1Value (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a SRATIONAL [numerator] value from an EXIF tag.
GAIAEXIF_DECLARE int	gaiaExifTagGetSignedRational2Value (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a SRATIONAL [denominator] value from an EXIF tag.
GAIAEXIF_DECLARE double	gaiaExifTagGetSignedRationalValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a Signed RATIONAL value from an EXIF tag.
GAIAEXIF_DECLARE float	gaiaExifTagGetFloatValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a FLOAT value from an EXIF tag.
GAIAEXIF_DECLARE double	gaiaExifTagGetDoubleValue (const gaiaExifTagPtr tag, const int ind, int *ok)
	Return a DOUBLE value from an EXIF tag.
GAIAEXIF_DECLARE void	gaiaExifTagGetHumanReadable (const gaiaExifTagPtr tag, char *str, int len, int *ok)
	Return a human readable description from an EXIF tag.
GAIAEXIF_DECLARE int	gaiaGuessBlobType (const unsigned char *blob, int size)
	Attempts to guess the actual content-type of some BLOB.
GAIAEXIF_DECLARE int	gaiaGetGpsCoords (const unsigned char *blob, int size, double *longitude, double *latitude)
	Return longitude and latitude from an EXIF-GPS tag.
GAIAEXIF_DECLARE int	gaiaGetGpsLatLong (const unsigned char *blob, int size, char *latlong, int ll_size)
	Return a text string representing DMS coordinates from an EXIF-GPS tag.

---

Detailed Description

EXIF/image: supporting functions and constants.

---

Typedef Documentation

typedef gaiaExifTagList* gaiaExifTagListPtr

Typedef for EXIF tag structure.

See also:

gaiaExifTagListStruct

typedef gaiaExifTag* gaiaExifTagPtr

Typedef for EXIF tag structure.

See also:

gaiaExifTagStruct

---

Function Documentation

GAIAEXIF_DECLARE unsigned char gaiaExifTagGetByteValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a BYTE value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the BYTE value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE double gaiaExifTagGetDoubleValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a DOUBLE value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the DOUBLE value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE float gaiaExifTagGetFloatValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a FLOAT value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the FLOAT value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE void gaiaExifTagGetHumanReadable	(	const gaiaExifTagPtr	tag,
		char *	str,
		int	len,
		int *	ok
	)

Return a human readable description from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
str	receiving buffer: the STRING value will be copied here.
len	length of the receiving buffer
ok	on completion will contain 0 on failure: any other value on success.

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName

GAIAEXIF_DECLARE unsigned short gaiaExifTagGetId

(

const gaiaExifTagPtr

tag

)

Return the Tag ID from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag

Returns:

the Tag ID

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName

GAIAEXIF_DECLARE unsigned int gaiaExifTagGetLongValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a LONG value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the LONG value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE void gaiaExifTagGetName	(	const gaiaExifTagPtr	tag,
		char *	tag_name,
		int	len
	)

Return the Tag Name from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag
tag_name	receiving buffer: the Tag Name will be copied here
len	length of the receiving buffer

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName

GAIAEXIF_DECLARE unsigned short gaiaExifTagGetNumValues

(

const gaiaExifTagPtr

tag

)

Return the total count of values from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag

Returns:

the number of available values

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName

GAIAEXIF_DECLARE unsigned int gaiaExifTagGetRational1Value	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a RATIONAL [numerator] value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the RATIONAL [numerator] value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE unsigned int gaiaExifTagGetRational2Value	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a RATIONAL [denominator] value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the RATIONAL [denominator] value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE double gaiaExifTagGetRationalValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a RATIONAL value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the RATIONAL value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE unsigned short gaiaExifTagGetShortValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a SHORT value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the SHORT value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE int gaiaExifTagGetSignedLongValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a Signed LONG value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the Signed LONG value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE int gaiaExifTagGetSignedRational1Value	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a SRATIONAL [numerator] value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the SRATIONAL [numerator] value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE int gaiaExifTagGetSignedRational2Value	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a SRATIONAL [denominator] value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the SRATIONAL [denominator] value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE double gaiaExifTagGetSignedRationalValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a Signed RATIONAL value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the Signed RATIONAL value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE short gaiaExifTagGetSignedShortValue	(	const gaiaExifTagPtr	tag,
		const int	ind,
		int *	ok
	)

Return a Signed SHORT value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
ind	value index [first value has index 0].
ok	on completion will contain 0 on failure: any other value on success.

Returns:

the Signed SHORT value

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE void gaiaExifTagGetStringValue	(	const gaiaExifTagPtr	tag,
		char *	str,
		int	len,
		int *	ok
	)

Return a STRING value from an EXIF tag.

Parameters:

tag	pointer to an EXIF tag.
str	receiving buffer: the STRING value will be copied here.
len	length of the receiving buffer
ok	on completion will contain 0 on failure: any other value on success.

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaExifTagGetValueType, gaiaExifTagGetNumValues

GAIAEXIF_DECLARE unsigned short gaiaExifTagGetValueType

(

const gaiaExifTagPtr

tag

)

Return the value type for an EXIF tag.

Parameters:

tag	pointer to an EXIF tag

Returns:

the value type: one of GAIA_EXIF_NONE, GAIA_EXIF_BYTE, GAIA_EXIF_SHORT, GAIA_EXIF_STRING, GAIA_EXIF_LONG, GAIA_EXIF_RATIONAL, GAIA_EXIF_SLONG, GAIA_EXIF_SRATIONAL

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName

GAIAEXIF_DECLARE void gaiaExifTagsFree

(

gaiaExifTagListPtr

tag_list

)

Destroy a list of EXIF tags.

Parameters:

tag_list

the list to be destroied

See also:

gaiaGetExifTags

Note:

the pointer passed to this function must be one returned by a previous call to gaiaGetExifTags

GAIAEXIF_DECLARE gaiaExifTagPtr gaiaGetExifGpsTagById	(	const gaiaExifTagListPtr	tag_list,
		const unsigned short	tag_id
	)

Retrieves an EXIF-GPS tag by its Tag ID.

Parameters:

tag_list	pointer to an EXIF tag list.
tag_id	the GPS Tag ID to be found

Returns:

a pointer to the corresponding EXIF tag: NULL if not found

See also:

gaiaGetExifTags, gaiaExifTagsFree

GAIAEXIF_DECLARE gaiaExifTagPtr gaiaGetExifTagById	(	const gaiaExifTagListPtr	tag_list,
		const unsigned short	tag_id
	)

Retrieves an EXIF tag by its Tag ID.

Parameters:

tag_list	pointer to an EXIF tag list.
tag_id	the Tag ID to be found

Returns:

a pointer to the corresponding EXIF tag: NULL if not found

See also:

gaiaGetExifTags, gaiaExifTagsFree

GAIAEXIF_DECLARE gaiaExifTagPtr gaiaGetExifTagByName	(	const gaiaExifTagListPtr	tag_list,
		const char *	tag_name
	)

Retrieves an EXIF tag by its name.

Parameters:

tag_list	pointer to an EXIF tag list.
tag_name	the Tag Name to be found

Returns:

a pointer to the corresponding EXIF tag: NULL if not found

See also:

gaiaGetExifTags, gaiaExifTagsFree

GAIAEXIF_DECLARE gaiaExifTagPtr gaiaGetExifTagByPos	(	gaiaExifTagListPtr	tag_list,
		const int	pos
	)

Retrieves an EXIF tag by its relative position into the list.

Parameters:

tag_list	pointer to an EXIF tag list.
pos	relative item position [first item is 0]

Returns:

a pointer to the corresponding EXIF tag: NULL if not found

See also:

gaiaGetExifTags, gaiaExifTagsFree, gaiaExifTagsCount

GAIAEXIF_DECLARE gaiaExifTagListPtr gaiaGetExifTags	(	const unsigned char *	blob,
		int	size
	)

Creates a list of EXIF tags by parsing a BLOB of the JPEG-EXIF type.

Parameters:

blob	the BLOB to be parsed
size	the BLOB size (in bytes)

Returns:

a list of EXIF tags: or NULL if any error is encountered

See also:

gaiaExifTagsFree

Note:

you must explicitly destroy the list when it's any longer used.

GAIAEXIF_DECLARE int gaiaGetExifTagsCount

(

gaiaExifTagListPtr

tag_list

)

Return the total number of EXIF tags into the list.

Parameters:

tag_list

pointer to an EXIF tag list.

Returns:

the EXIF tag count.

See also:

gaiaGetExifTags, gaiaExifTagsFree

GAIAEXIF_DECLARE int gaiaGetGpsCoords	(	const unsigned char *	blob,
		int	size,
		double *	longitude,
		double *	latitude
	)

Return longitude and latitude from an EXIF-GPS tag.

Parameters:

blob	the BLOB to be parsed
size	length of the BLOB (in bytes)
longitude	on success will contain the longitude coordinate
latitude	on success will contain the latitude coordinate

Returns:

0 on failure: any other value on success

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaIsExifGpsTag

GAIAEXIF_DECLARE int gaiaGetGpsLatLong	(	const unsigned char *	blob,
		int	size,
		char *	latlong,
		int	ll_size
	)

Return a text string representing DMS coordinates from an EXIF-GPS tag.

Parameters:

blob	the BLOB to be parsed
size	length of the BLOB (in bytes)
latlong	receiving buffer: the text string will be copied here.
ll_size	length of the receiving buffer

Returns:

0 on failure: any other value on success

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName, gaiaIsExifGpsTag

GAIAEXIF_DECLARE int gaiaGuessBlobType	(	const unsigned char *	blob,
		int	size
	)

Attempts to guess the actual content-type of some BLOB.

Parameters:

blob	the BLOB to be parsed
size	length of the BLOB (in bytes)

Returns:

the BLOB type: one of GAIA_HEX_BLOB, GAIA_GIF_BLOB, GAIA_PNG_BLOB, GAIA_JPEG_BLOB, GAIA_EXIF_BLOB, GAIA_EXIF_GPS_BLOB, GAIA_ZIP_BLOB, GAIA_PDF_BLOB, GAIA_GEOMETRY_BLOB, GAIA_TIFF_BLOB

GAIAEXIF_DECLARE int gaiaIsExifGpsTag

(

const gaiaExifTagPtr

tag

)

Checks if an EXIF tag actually is an EXIF-GPS tag.

Parameters:

tag	pointer to an EXIF tag

Returns:

0 if false: any other value if true

See also:

gaiaGetExifTagById, gaiaGetExifGpsTagById, gaiaGetExifTagByName