XMP

XMP — Extensible Metadata Platform (XMP)

Stability Level

Stable, unless otherwise indicated

Synopsis

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

                    TrackerXmpData;
                    TrackerXmpRegion;
TrackerXmpData *    tracker_xmp_new                     (const gchar *buffer,
                                                         gsize len,
                                                         const gchar *uri);
void                tracker_xmp_free                    (TrackerXmpData *data);
gboolean            tracker_xmp_read                    (const gchar *buffer,
                                                         size_t len,
                                                         const gchar *uri,
                                                         TrackerXmpData *data);
gboolean            tracker_xmp_apply                   (TrackerSparqlBuilder *preupdate,
                                                         TrackerSparqlBuilder *metadata,
                                                         const gchar *graph,
                                                         GString *where,
                                                         const gchar *uri,
                                                         TrackerXmpData *data);
gboolean            tracker_xmp_apply_regions           (TrackerSparqlBuilder *preupdate,
                                                         TrackerSparqlBuilder *metadata,
                                                         const gchar *graph,
                                                         TrackerXmpData *data);

Description

The Adobe Extensible Metadata Platform (XMP) is a standard, created by Adobe Systems Inc., for processing and storing standardized and proprietary information relating to the contents of a file.

XMP standardizes the definition, creation, and processing of extensible metadata. Serialized XMP can be embedded into a significant number of popular file formats, without breaking their readability by non-XMP-aware applications. Embedding metadata ("the truth is in the file") avoids many problems that occur when metadata is stored separately. XMP is used in PDF, photography and photo editing applications.

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

Details

TrackerXmpData

typedef struct {
	/* NS_DC */
	gchar *title;
	gchar *rights;
	gchar *creator;
	gchar *description;
	gchar *date;
	gchar *keywords;
	gchar *subject;

	gchar *publisher;
	gchar *contributor;
	gchar *type;
	gchar *format;
	gchar *identifier;
	gchar *source;
	gchar *language;
	gchar *relation;
	gchar *coverage;

	/* NS_CC */
	gchar *license;

	/* NS_PDF */
	gchar *pdf_title;
	gchar *pdf_keywords;

	/* NS_EXIF */
	gchar *title2;
	gchar *time_original;
	gchar *artist;
	gchar *make;
	gchar *model;
	gchar *orientation;
	gchar *flash;
	gchar *metering_mode;
	gchar *exposure_time;
	gchar *fnumber;
	gchar *focal_length;

	gchar *iso_speed_ratings;
	gchar *white_balance;
	gchar *copyright;

	/* TODO NS_XAP*/
	gchar *rating;

	/* TODO NS_IPTC4XMP */
	/* TODO NS_PHOTOSHOP */
	gchar *address;
	gchar *country;
	gchar *state;
	gchar *city;

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

	/* List of TrackerXmpRegion */
        GSList *regions;
} TrackerXmpData;


TrackerXmpRegion

typedef struct {
        gchar *title;
        gchar *description;
        gchar *type;
        gchar *x;
        gchar *y;
        gchar *width;
        gchar *height;
        gchar *link_class;
        gchar *link_uri;
} TrackerXmpRegion;


tracker_xmp_new ()

TrackerXmpData *    tracker_xmp_new                     (const gchar *buffer,
                                                         gsize len,
                                                         const gchar *uri);

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

buffer :

a chunk of data with xmp data in it.

len :

the size of buffer.

uri :

the URI this is related to.

Returns :

a newly allocated TrackerXmpData struct if XMP data was found, NULL otherwise. Free the returned struct with tracker_xmp_free().

Since 0.10


tracker_xmp_free ()

void                tracker_xmp_free                    (TrackerXmpData *data);

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

data :

a TrackerXmpData struct

Since 0.10


tracker_xmp_read ()

gboolean            tracker_xmp_read                    (const gchar *buffer,
                                                         size_t len,
                                                         const gchar *uri,
                                                         TrackerXmpData *data);

Warning

tracker_xmp_read is deprecated and should not be used in newly-written code. 0.9. Use tracker_xmp_new() instead.

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

buffer :

a chunk of data with xmp data in it.

len :

the size of buffer.

uri :

the URI this is related to.

data :

a pointer to a TrackerXmpData structure to populate.

Returns :

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

Since 0.8


tracker_xmp_apply ()

gboolean            tracker_xmp_apply                   (TrackerSparqlBuilder *preupdate,
                                                         TrackerSparqlBuilder *metadata,
                                                         const gchar *graph,
                                                         GString *where,
                                                         const gchar *uri,
                                                         TrackerXmpData *data);

This function applies all data in data to metadata.

The graph parameter was added in 0.12.

This function also calls tracker_xmp_apply_regions(), so there is no need to call both functions.

preupdate :

the preupdate object to apply XMP data to.

metadata :

the metadata object to apply XMP data to.

graph :

the graph to apply XMP data to.

where :

the where object.

uri :

the URI this is related to.

data :

the data to push into metadata.

Returns :

TRUE if the data was applied to metadata successfully, otherwise FALSE is returned.

Since 0.8


tracker_xmp_apply_regions ()

gboolean            tracker_xmp_apply_regions           (TrackerSparqlBuilder *preupdate,
                                                         TrackerSparqlBuilder *metadata,
                                                         const gchar *graph,
                                                         TrackerXmpData *data);

This function applies all regional data to preupdate and metadata. Regional data exists for image formats like JPEG, PNG, etc. where parts of the image refer to areas of interest. This can be people's faces, places to focus, barcodes, etc. The regional data describes the title, height, width, X, Y and can occur multiple times in a given file.

This data usually is standardized between image formats and that's what makes this function different to tracker_xmp_apply() which is useful for XMP files only.

preupdate :

the preupdate object to apply XMP data to.

metadata :

the metadata object to apply XMP data to.

graph :

the graph to apply XMP data to.

data :

the data to push into preupdate and metadata.

Returns :

TRUE if the data was applied to preupdate and metadata successfully, otherwise FALSE is returned.

Since 0.12