### Class

# Gegl MetadataHash

#### Description

    final class Gegl.MetadataHash : Gegl.MetadataStore
      implements Gegl.Metadata {
      /* No available fields */
    }

No description available.

#### Hierarchy

#### Ancestors

- GeglMetadataStore
- GObject

#### Implements

- GeglMetadata

#### Constructors

###### gegl_metadata_hash_new

Create a new `GeglMetadataHash`.

#### Instance methods

##### Methods inherited from GeglMetadataStore (36)

Please see GeglMetadataStore for a full list of methods.

##### Methods inherited from GObject (43)

Please see GObject for a full list of methods.

##### Methods inherited from GeglMetadata (9)

###### gegl_metadata_get_resolution

Retrieve resolution from the application image metadata. Intended for use by the image file writer. If resolution is not supported by the application or if the operation fails `FALSE` is returned and the resolution values are not updated.

###### gegl_metadata_iter_get_value

Retrieve image file metadata from the application. Intended for use by the image file writer. If the operation fails it returns `FALSE` and `value` is not updated.

###### gegl_metadata_iter_init

Initialise an iterator to find all supported metadata keys.

###### gegl_metadata_iter_lookup

Look up the specified key and initialise an iterator to reference the associated metadata. The iterator is used in conjunction with `gegl_metadata_set_value()` and gegl_metadata_get_value(). Note that this iterator is not valid for gegl_metadata_iter_next().

###### gegl_metadata_iter_next

Move the iterator to the next metadata item.

###### gegl_metadata_iter_set_value

Set application data retrieved from image file’s metadata. Intended for use by the image file reader. If the operation fails it returns `FALSE` and `value` is ignored.

###### gegl_metadata_register_map

Set the name of the file module and pass an array of mappings from file-format specific metadata names to those used by Gegl. A GValue transformation function may be supplied, e.g. to parse or format timestamps.

###### gegl_metadata_set_resolution

Set resolution retrieved from image file’s metadata. Intended for use by the image file reader. If resolution is not supported by the application or if the operation fails `FALSE` is returned and the values are ignored.

###### gegl_metadata_unregister_map

Unregister the file module mappings and any further mappings added or modified by the application. This should be called after the file module completes operations.

#### Properties

##### Properties inherited from GeglMetadataStore (14)

###### Gegl.MetadataStore:artist

Name of image creator.

###### Gegl.MetadataStore:comment

Miscellaneous comment; conversion from GIF comment.

###### Gegl.MetadataStore:copyright

Copyright notice.

###### Gegl.MetadataStore:description

Description of image (possibly long).

###### Gegl.MetadataStore:disclaimer

Legal disclaimer.

###### Gegl.MetadataStore:file-module-name

Current file loader/saver module name. Valid only while a `GeglMetadata` mapping is registered. This property is mainly provided for use in signal handlers.

###### Gegl.MetadataStore:resolution-unit

A `GeglResolutionUnit` specifying units for the image resolution (density).

###### Gegl.MetadataStore:resolution-x

X resolution or density in dots per unit.

###### Gegl.MetadataStore:resolution-y

Y resolution or density in dots per unit.

###### Gegl.MetadataStore:software

Software used to create the image.

###### Gegl.MetadataStore:source

Device used to create the image.

###### Gegl.MetadataStore:timestamp

Time of original image creation.

###### Gegl.MetadataStore:title

Short (one line) title or caption for image.

###### Gegl.MetadataStore:warning

Warning of nature of content.

#### Signals

##### Signals inherited from GeglMetadataStore (5)

###### GeglMetadataStore::changed

`::changed` is emitted when a metadata value is changed. This is analogous to the `GObject::notify` signal.

###### GeglMetadataStore::generate-value

If a signal handler is connected to `::generate-value` a signal is emitted when the file module accesses a value using gegl_metadata_get_value(). The signal handler must generate a value of the type specified in the pspec argument. The signal handler’s return value indicates the success of the operation.

###### GeglMetadataStore::mapped

`::mapped` is emitted after a file module registers a mapping and before other processing takes place. An application may respond to the signal by registering additional mappings or overriding existing values, for example it might override the TIFF ImageDescription tag to format multiple metadata values into the description.

###### GeglMetadataStore::parse-value

If a signal handler is connected to `::parse-value` a signal is emitted when the file module accesses a value using gegl_metadata_set_value(). The signal handler should parse the value supplied in the `GValue` and may set any number of metadata values using gegl_metadata_store_set_value().

###### GeglMetadataStore::unmapped

`::unmapped` is emitted when a file module tries to look up an unmapped metadata name. When the handler returns a second attempt is made to look up the metadata.

##### Signals inherited from GObject (1)

###### GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

#### Class structure

    struct GeglMetadataHashClass {
      GeglMetadataStoreClass parent_class;

    }

No description available.

###### Class members

`parent_class: GeglMetadataStoreClass`

  No description available.