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_XML_BLOB   11
	this BLOB does actually contain a SpatiaLite XmlBLOB
#define	GAIA_GPB_BLOB   12
	this BLOB does actually contain a GPKG Geometry
#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. More...
typedef struct gaiaExifTagListStruct	gaiaExifTagList
	Container for a list of EXIF tags.
typedef gaiaExifTagList *	gaiaExifTagListPtr
	Typedef for EXIF tag structure. More...

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

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, GAIA_WEBP_BLOB, GAIA_XML_BLOB, GAIA_GPB_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