Tracker Extract Library Reference Manual: Exif

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Exif

Exif — Exchangeable Image File Format (EXIF)

Stability Level

Stable, unless otherwise indicated

Functions

TrackerExifData *	tracker_exif_new ()
void	tracker_exif_free ()
gboolean	tracker_exif_read ()

Types and Values

TrackerExifData

Object Hierarchy

Includes

#include <libtracker-extract/tracker-extract.h>

Description

Exchangeable Image File Format (EXIF) is a specification for the image file format used by digital cameras. The specification uses the existing JPEG, TIFF Rev. 6.0, and RIFF WAV file formats, with the addition of specific metadata tags. It is not supported in JPEG 2000, PNG, or GIF.

This API is provided to remove code duplication between extractors using these standards.

Functions

tracker_exif_new ()

TrackerExifData *
tracker_exif_new (const guchar *buffer,
                  size_t len,
                  const gchar *uri);

This function takes len bytes of buffer and runs it through the EXIF library.

Parameters

buffer	a chunk of data with exif data in it.
len	the size of `buffer` .
uri	the URI this is related to.

Returns

a newly allocated TrackerExifData struct if EXIF data was found, NULL otherwise. Free the returned struct with tracker_exif_free().

Since 0.10

tracker_exif_free ()

void
tracker_exif_free (TrackerExifData *data);

Frees data and all TrackerExifData members. NULL will produce a a warning.

Parameters

data

a TrackerExifData

Since 0.10

tracker_exif_read ()

gboolean
tracker_exif_read (const unsigned char *buffer,
                   size_t len,
                   const gchar *uri,
                   TrackerExifData *data);

tracker_exif_read has been deprecated since version 0.9. and should not be used in newly-written code.

Use tracker_exif_new() instead.

This function takes len bytes of buffer and runs it through the EXIF library. The result is that data is populated with the EXIF data found in uri .

Parameters

buffer	a chunk of data with exif data in it.
len	the size of `buffer` .
uri	the URI this is related to.
data	a pointer to a TrackerExifData struture to populate.

Returns

TRUE if the data was populated successfully, otherwise FALSE is returned.

Since 0.8

Types and Values

TrackerExifData

typedef struct {
	gchar *y_dimension;
	gchar *x_dimension;
	gchar *image_width;
	gchar *document_name;
	gchar *time;
	gchar *time_original;
	gchar *artist;
	gchar *user_comment;
	gchar *description;
	gchar *make;
	gchar *model;
	gchar *orientation;
	gchar *exposure_time;
	gchar *fnumber;
	gchar *flash;
	gchar *focal_length;
	gchar *iso_speed_ratings;
	gchar *metering_mode;
	gchar *white_balance;
	gchar *copyright;
	gchar *software;
	gchar *x_resolution;
	gchar *y_resolution;
	gint resolution_unit;

	/* ABI barrier (don't change things above this) */
	gchar *gps_altitude;
	gchar *gps_latitude;
	gchar *gps_longitude;
	gchar *gps_direction;
} TrackerExifData;

Structure defining EXIF data.

Members

gchar *`y_dimension`;	Y dimension.
gchar *`x_dimension`;	X dimension.
gchar *`image_width`;	Image width.
gchar *`document_name`;	Document name.
gchar *`time`;	Time.
gchar *`time_original`;	Original time.
gchar *`artist`;	Artist.
gchar *`user_comment`;	User-provided comment.
gchar *`description`;	Description.
gchar *`make`;	Make info.
gchar *`model`;	Model info.
gchar *`orientation`;	Orientation.
gchar *`exposure_time`;	Exposure time.
gchar *`fnumber`;	Focal ratio
gchar *`flash`;	Flash info.
gchar *`focal_length`;	Focal length.
gchar *`iso_speed_ratings`;	ISO speed ratings.
gchar *`metering_mode`;	Metering mode.
gchar *`white_balance`;	White balance.
gchar *`copyright`;	Copyright.
gchar *`software`;	Software used.
gchar *`x_resolution`;	Horizontal resolution.
gchar *`y_resolution`;	Vertical resolution.
gint `resolution_unit`;	Resolution units.
gchar *`gps_altitude`;	GPS altitude.
gchar *`gps_latitude`;	GPS latitude.
gchar *`gps_longitude`;	GPS longitude.
gchar *`gps_direction`;	GPS direction information.