gexiv2_metadata_new ()

GExiv2Metadata *
gexiv2_metadata_new (void);

gexiv2_metadata_free ()

void
gexiv2_metadata_free (GExiv2Metadata *self);

Destroys the GExiv2Metadata object and frees all associated memory.

gexiv2_metadata_open_path ()

gboolean
gexiv2_metadata_open_path (GExiv2Metadata *self,
                           const gchar *path,
                           GError **error);

The file must be an image format supported by Exiv2.

gexiv2_metadata_open_buf ()

gboolean
gexiv2_metadata_open_buf (GExiv2Metadata *self,
                          const guint8 *data,
                          glong n_data,
                          GError **error);

The buffer must be an image format supported by Exiv2.

gexiv2_metadata_open_stream ()

gboolean
gexiv2_metadata_open_stream (GExiv2Metadata *self,
                             ManagedStreamCallbacks *cb,
                             GError **error);

The stream must be an image format supported by Exiv2.

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gexiv2_metadata_from_app1_segment ()

gboolean
gexiv2_metadata_from_app1_segment (GExiv2Metadata *self,
                                   const guint8 *data,
                                   glong n_data,
                                   GError **error);

Load only an EXIF buffer, typically stored in a JPEG's APP1 segment.

gexiv2_metadata_save_file ()

gboolean
gexiv2_metadata_save_file (GExiv2Metadata *self,
                           const gchar *path,
                           GError **error);

Saves the metadata to the specified file by reading the file into memory,copying this object's metadata into the image, then writing the image back out.

gexiv2_metadata_save_stream ()

gboolean
gexiv2_metadata_save_stream (GExiv2Metadata *self,
                             ManagedStreamCallbacks *cb,
                             GError **error);

Saves the metadata to the stream by reading the stream into memory,copying this object's metadata into the image, then writing the image as a stream back out.

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gexiv2_metadata_has_tag ()

gboolean
gexiv2_metadata_has_tag (GExiv2Metadata *self,
                         const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_clear_tag ()

gboolean
gexiv2_metadata_clear_tag (GExiv2Metadata *self,
                           const gchar *tag);

Removes the Exiv2 tag from the metadata object.

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_clear ()

void
gexiv2_metadata_clear (GExiv2Metadata *self);

Removes all tags for all domains (EXIF, IPTC, and XMP).

gexiv2_metadata_is_exif_tag ()

gboolean
gexiv2_metadata_is_exif_tag (const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_is_iptc_tag ()

gboolean
gexiv2_metadata_is_iptc_tag (const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_is_xmp_tag ()

gboolean
gexiv2_metadata_is_xmp_tag (const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_tag_label ()

const gchar *
gexiv2_metadata_get_tag_label (const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_tag_description ()

const gchar *
gexiv2_metadata_get_tag_description (const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_tag_type ()

const gchar *
gexiv2_metadata_get_tag_type (const gchar *tag);

The names of the various Exiv2 tag types can be found at Exiv2::TypeId,

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_supports_exif ()

gboolean
gexiv2_metadata_get_supports_exif (GExiv2Metadata *self);

Query self whehter it suports writing EXIF metadata.

gexiv2_metadata_get_supports_iptc ()

gboolean
gexiv2_metadata_get_supports_iptc (GExiv2Metadata *self);

Query self whether it supports writing IPTC metadata.

gexiv2_metadata_get_supports_xmp ()

gboolean
gexiv2_metadata_get_supports_xmp (GExiv2Metadata *self);

Query self whether it supports writing XMP metadata.

gexiv2_metadata_get_mime_type ()

const gchar *
gexiv2_metadata_get_mime_type (GExiv2Metadata *self);

Query mime type of currently loaded image.

gexiv2_metadata_get_pixel_width ()

gint
gexiv2_metadata_get_pixel_width (GExiv2Metadata *self);

Get the actual unoriented display width in pixels of the loaded image. May be different than the width reported by various metadata tags, i.e. "Exif.Photo.PixelXDimension".

gexiv2_metadata_get_pixel_height ()

gint
gexiv2_metadata_get_pixel_height (GExiv2Metadata *self);

Get the actual unoriented display height in pixels of the loaded image. This may be different than the height reported by various metadata tags, i.e. "Exif.Photo.PixelYDimension".

gexiv2_metadata_get_tag_string ()

gchar *
gexiv2_metadata_get_tag_string (GExiv2Metadata *self,
                                const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_set_tag_string ()

gboolean
gexiv2_metadata_set_tag_string (GExiv2Metadata *self,
                                const gchar *tag,
                                const gchar *value);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_set_xmp_tag_struct ()

gboolean
gexiv2_metadata_set_xmp_tag_struct (GExiv2Metadata *self,
                                    const gchar *tag,
                                    GExiv2StructureType type);

gexiv2_metadata_get_tag_interpreted_string ()

gchar *
gexiv2_metadata_get_tag_interpreted_string
                               (GExiv2Metadata *self,
                                const gchar *tag);

An interpreted string is one fit for user display. It may display units or use formatting appropriate to the type of data the tag holds.

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_tag_long ()

glong
gexiv2_metadata_get_tag_long (GExiv2Metadata *self,
                              const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_set_tag_long ()

gboolean
gexiv2_metadata_set_tag_long (GExiv2Metadata *self,
                              const gchar *tag,
                              glong value);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_tag_multiple ()

gchar **
gexiv2_metadata_get_tag_multiple (GExiv2Metadata *self,
                                  const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_set_tag_multiple ()

gboolean
gexiv2_metadata_set_tag_multiple (GExiv2Metadata *self,
                                  const gchar *tag,
                                  const gchar **values);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_get_tag_raw ()

GBytes *
gexiv2_metadata_get_tag_raw (GExiv2Metadata *self,
                             const gchar *tag);

The Exiv2 Tag Reference can be found at http://exiv2.org/metadata.html

gexiv2_metadata_has_exif ()

gboolean
gexiv2_metadata_has_exif (GExiv2Metadata *self);

gexiv2_metadata_clear_exif ()

void
gexiv2_metadata_clear_exif (GExiv2Metadata *self);

Clears all EXIF metadata from the loaded image.

gexiv2_metadata_get_exif_tags ()

gchar **
gexiv2_metadata_get_exif_tags (GExiv2Metadata *self);

Query self for a list of available EXIF tags

gexiv2_metadata_get_exif_tag_rational ()

gboolean
gexiv2_metadata_get_exif_tag_rational (GExiv2Metadata *self,
                                       const gchar *tag,
                                       gint *nom,
                                       gint *den);

Fetch EXIF tag represented by a fraction. nom will contian the numerator, den the denominator of the fraction on successful return.

gexiv2_metadata_set_exif_tag_rational ()

gboolean
gexiv2_metadata_set_exif_tag_rational (GExiv2Metadata *self,
                                       const gchar *tag,
                                       gint nom,
                                       gint den);

Set EXIF tag represented by a fraction, with nom being the numerator, den the denominator of the fraction.

gexiv2_metadata_get_exif_thumbnail ()

gboolean
gexiv2_metadata_get_exif_thumbnail (GExiv2Metadata *self,
                                    guint8 **buffer,
                                    gint *size);

Get the thumbnail stored in the EXIF data of self

gexiv2_metadata_set_exif_thumbnail_from_file ()

gboolean
gexiv2_metadata_set_exif_thumbnail_from_file
                               (GExiv2Metadata *self,
                                const gchar *path,
                                GError **error);

Sets or replaces the EXIF thumbnail with the image in the file

gexiv2_metadata_set_exif_thumbnail_from_buffer ()

void
gexiv2_metadata_set_exif_thumbnail_from_buffer
                               (GExiv2Metadata *self,
                                const guint8 *buffer,
                                gint size);

gexiv2_metadata_erase_exif_thumbnail ()

void
gexiv2_metadata_erase_exif_thumbnail (GExiv2Metadata *self);

Removes the EXIF thumbnail from the loaded image.

gexiv2_metadata_has_xmp ()

gboolean
gexiv2_metadata_has_xmp (GExiv2Metadata *self);

gexiv2_metadata_clear_xmp ()

void
gexiv2_metadata_clear_xmp (GExiv2Metadata *self);

Clears all XMP metadata from the loaded image.

gexiv2_metadata_generate_xmp_packet ()

gchar *
gexiv2_metadata_generate_xmp_packet (GExiv2Metadata *self,
                                     GExiv2XmpFormatFlags xmp_format_flags,
                                     guint32 padding);

Encode the XMP packet as a NULL-terminated string.

gexiv2_metadata_get_xmp_packet ()

gchar *
gexiv2_metadata_get_xmp_packet (GExiv2Metadata *self);

gexiv2_metadata_get_xmp_tags ()

gchar **
gexiv2_metadata_get_xmp_tags (GExiv2Metadata *self);

gexiv2_metadata_register_xmp_namespace ()

gboolean
gexiv2_metadata_register_xmp_namespace
                               (const gchar *name,
                                const gchar *prefix);

gexiv2_metadata_unregister_xmp_namespace ()

gboolean
gexiv2_metadata_unregister_xmp_namespace
                               (const gchar *name);

gexiv2_metadata_unregister_all_xmp_namespaces ()

void
gexiv2_metadata_unregister_all_xmp_namespaces
                               (void);

gexiv2_metadata_has_iptc ()

gboolean
gexiv2_metadata_has_iptc (GExiv2Metadata *self);

gexiv2_metadata_clear_iptc ()

void
gexiv2_metadata_clear_iptc (GExiv2Metadata *self);

Clears all IPTC metadata from the loaded image.

gexiv2_metadata_get_iptc_tags ()

gchar **
gexiv2_metadata_get_iptc_tags (GExiv2Metadata *self);

Query self for a list of available IPTC tags

gexiv2_metadata_get_orientation ()

GExiv2Orientation
gexiv2_metadata_get_orientation (GExiv2Metadata *self);

The EXIF Orientation field

gexiv2_metadata_set_orientation ()

void
gexiv2_metadata_set_orientation (GExiv2Metadata *self,
                                 GExiv2Orientation orientation);

The orientation must be valid and cannot be GEXIV2_ORIENTATION_UNSPECIFIED.

gexiv2_metadata_get_metadata_pixel_width ()

gint
gexiv2_metadata_get_metadata_pixel_width
                               (GExiv2Metadata *self);

Composite accessor to query the pixel with stored in the metadata. This might differ from the width of image that is available through gexiv2_metadata_get_pixel_width()

gexiv2_metadata_get_metadata_pixel_height ()

gint
gexiv2_metadata_get_metadata_pixel_height
                               (GExiv2Metadata *self);

Composite accessor to query the pixel with stored in the metadata. This might differ from the height of image that is available through gexiv2_metadata_get_pixel_height()

gexiv2_metadata_set_metadata_pixel_width ()

void
gexiv2_metadata_set_metadata_pixel_width
                               (GExiv2Metadata *self,
                                gint width);

Composite setter to update the image's metadata with width

gexiv2_metadata_set_metadata_pixel_height ()

void
gexiv2_metadata_set_metadata_pixel_height
                               (GExiv2Metadata *self,
                                gint height);

Update the image's metadata with height

gexiv2_metadata_get_comment ()

gchar *
gexiv2_metadata_get_comment (GExiv2Metadata *self);

A composite accessor that uses the first available metadata field from a list of well-known locations to find the photo's comment (or description).

MWG guidelines refer to these as Description: a textual description of a resource's content.

These fields are:

For fine-grained control, it's recommened to use Exiv2 tags directly rather than this method, which is more useful for quick or casual use.

gexiv2_metadata_set_comment ()

void
gexiv2_metadata_set_comment (GExiv2Metadata *self,
                             const gchar *comment);

This is a composite setter that will set a number of fields to the supplied value. See gexiv2_metadata_get_comment for more informtion.

gexiv2_metadata_clear_comment ()

void
gexiv2_metadata_clear_comment (GExiv2Metadata *self);

This is a composite clear method that will clear a number of fields. See gexiv2_metadata_get_comment for more informtion.

gexiv2_metadata_get_exposure_time ()

gboolean
gexiv2_metadata_get_exposure_time (GExiv2Metadata *self,
                                   gint *nom,
                                   gint *den);

Returns the exposure time in seconds (shutter speed, not date-time of exposure) as a rational. See https://en.wikipedia.org/wiki/Shutter_speed for more information.

gexiv2_metadata_get_fnumber ()

gdouble
gexiv2_metadata_get_fnumber (GExiv2Metadata *self);

See https://en.wikipedia.org/wiki/F-number for more information.

gexiv2_metadata_get_focal_length ()

gdouble
gexiv2_metadata_get_focal_length (GExiv2Metadata *self);

See https://en.wikipedia.org/wiki/Flange_focal_distance for more information.

gexiv2_metadata_get_iso_speed ()

gint
gexiv2_metadata_get_iso_speed (GExiv2Metadata *self);

See https://en.wikipedia.org/wiki/Iso_speed for more information.

gexiv2_metadata_get_gps_longitude ()

gboolean
gexiv2_metadata_get_gps_longitude (GExiv2Metadata *self,
                                   gdouble *longitude);

Query the longitude stored in the GPS tags of self

gexiv2_metadata_get_gps_latitude ()

gboolean
gexiv2_metadata_get_gps_latitude (GExiv2Metadata *self,
                                  gdouble *latitude);

Query the latitude stored in the GPS tags of self

gexiv2_metadata_get_gps_altitude ()

gboolean
gexiv2_metadata_get_gps_altitude (GExiv2Metadata *self,
                                  gdouble *altitude);

Convenience functon to query the altitude stored in the GPS tags of the image

gexiv2_metadata_get_gps_info ()

gboolean
gexiv2_metadata_get_gps_info (GExiv2Metadata *self,
                              gdouble *longitude,
                              gdouble *latitude,
                              gdouble *altitude);

Convenience functon to query all available GPS information at once.

gexiv2_metadata_set_gps_info ()

gboolean
gexiv2_metadata_set_gps_info (GExiv2Metadata *self,
                              gdouble longitude,
                              gdouble latitude,
                              gdouble altitude);

Convenience functon to query all available GPS information at once.

gexiv2_metadata_delete_gps_info ()

void
gexiv2_metadata_delete_gps_info (GExiv2Metadata *self);

Removes all GPS metadata from the loaded image

gexiv2_metadata_get_preview_properties ()

GExiv2PreviewProperties **
gexiv2_metadata_get_preview_properties
                               (GExiv2Metadata *self);

An image may have stored one or more previews, often of different qualities, sometimes of different image formats than the containing image. This call returns the properties of all previews Exiv2 finds within the loaded image. Use gexiv2_metadata_get_preview_image to load a particular preview into memory.

gexiv2_metadata_get_preview_image ()

GExiv2PreviewImage *
gexiv2_metadata_get_preview_image (GExiv2Metadata *self,
                                   GExiv2PreviewProperties *props);

Stream_CanSeek ()

gboolean
(*Stream_CanSeek) (void *handle);

Function that returns the seekability of the stream

Stream_CanRead ()

gboolean
(*Stream_CanRead) (void *handle);

Function that returns the readability of the stream

Stream_CanWrite ()

gboolean
(*Stream_CanWrite) (void *handle);

Function that returns the readability of the stream

Stream_Length ()

gint64
(*Stream_Length) (void *handle);

Function to query the length of the stream

Stream_Position ()

gint64
(*Stream_Position) (void *handle);

Function to query the current position in the stream

Stream_Read ()

gint32
(*Stream_Read) (void *handle,
                void *buffer,
                gint32 offset,
                gint32 count);

Function to read data from the stream

Stream_Write ()

void
(*Stream_Write) (void *handle,
                 void *buffer,
                 gint32 offset,
                 gint32 count);

Function to write data to the stream

Stream_Seek ()

void
(*Stream_Seek) (void *handle,
                gint64 offset,
                WrapperSeekOrigin origin);

Change the read or write position in the current stream

Stream_Flush ()

void
(*Stream_Flush) (void *handle);

Schedule writing buffered data to the stream's real storage.

enum GExiv2Orientation

The orientation of an image is defined as the location of it's x,y origin. More than rotation, orientation allows for every variation of rotation, flips, and mirroring to be described in 3 bits of data.

A handy primer to orientation can be found at

enum GExiv2StructureType

Used in gexiv2_metadata_set_xmp_tag_struct() to determine the array type

enum GExiv2XmpFormatFlags

Options to control the format of the serialized XMP packet Taken from: exiv2/src/xmp.hpp

struct GExiv2Metadata

struct GExiv2Metadata;

An object holding all the Exiv2 metadata. Previews, if present, are also available.

As gexiv2 is only a wrapper around Exiv2, it's better to read its documentaiton to understand the full scope of what it offers: http://www.exiv2.org/

In particular, rather than providing a getter/setter method pair for every metadata value available for images (of which there are thousands), Exiv2 uses a dotted addressing scheme. For example, to access a photo's EXIF Orientation field, the caller passes to Exiv2 "Exif.Photo.Orientation". These tags (in Exiv2 parlance) are key to using Exiv2 (and therefore gexiv2) to its fullest.

A full reference for all supported Exiv2 tags can be found at

enum WrapperSeekOrigin

Seek positions for Stream_Seek

ManagedStreamCallbacks

typedef struct {
    void *handle;
    Stream_CanSeek CanSeek;
    Stream_CanRead CanRead;
    Stream_CanWrite CanWrite;
    Stream_Length Length;
    Stream_Position Position;
    Stream_Read Read;
    Stream_Write Write;
    Stream_Seek Seek;
    Stream_Flush Flush;
} ManagedStreamCallbacks;

ManagedStreamCallbacks is a set of callbacks that describe a stream that can be passed to gexiv2_metadata_open_stream() to read image meta-data from arbitrary data sources that can be mapped to this set of callbacks.

At least CanSeek and CanRead need to return TRUE and the relevant call-backs must not be NULL to be any useful.