generate_value |
object
|
r |
This method is called to optionally generate a value to be written to and image file. If no generator is available it returns False and the registered mapping is used. If a generator is available it should create a suitable value to be written to the image file and return True. The default method checks if a signal handler is registered for the generate-value signal with the variable name as the detail parameter. If a handler is registered it emits the signal with an initialised GObject.Value to receive the file metadata and returns True otherwise False. parse_value and generate_value are provided to handle the case where some file formats overload, for example, image comments. A typical case is formatting many values into a TIFF file’s ImageDescription field. |
has_value |
object
|
r |
The has_value virtual method implements Gegl.MetadataStore.has_value() It should return True if the variable is declared and contains a valid value of the correct type, otherwise False. This method MUST be provided by the subclass. |
padding |
[object] |
r |
|
parent_class |
GObject.ObjectClass
|
r |
|
parse_value |
object
|
r |
This method is called to optionally parse image file metadata prior to setting metadata variables in the Gegl.MetadataStore. If no parser is available it returns False and the registered mapping is used. If a parser available it should set one or more metadata variables using Gegl.MetadataStore.set_value() and return True. Note that the parser MUST return True even if setting individual values fails. The default method checks if a signal handler is registered for the parse-value signal with the variable name as the detail parameter. If a handler is registered it emits the signal with the file metadata provided as a GObject.Value and returns True otherwise False. |
pspec |
object
|
r |
The pspec virtual method returns the GObject.ParamSpec used to declare a metadata variable. It is used to implement Gegl.MetadataStore.typeof_value(). This method MUST be provided by the subclass. |
register_hook |
object
|
r |
This method is called after a file loader or saver registers a Gegl.MetadataMap and before any further processing takes place. It is intended to allow an application to create further application-specific mappings using Gegl.MetadataStore.register(). Gegl.MetadataStore provides a default method which emits the ::mapped signal. |
set_value |
object
|
r |
Set a metadata variable using a GObject.Value. Implements Gegl.MetadataStore.set_value(). The metadata variable should be declared and the GObject.Value must be of the correct type. Note that failure to set a variable may be dependent of properties of the underlying storage mechanism. This method MUST be provided by the subclass. |