Preset#

class Preset(*args, **kwargs)#

This interface offers methods to query and manipulate parameter preset sets. A preset is a bunch of property settings, together with meta data and a name. The name of a preset serves as key for subsequent method calls to manipulate single presets. All instances of one type will share the list of presets. The list is created on demand, if presets are not used, the list is not created.

The interface comes with a default implementation that serves most plugins. Wrapper plugins will override most methods to implement support for the native preset format of those wrapped plugins. One method that is useful to be overridden is get_property_names(). With that one can control which properties are saved and in which order. When implementing support for read-only presets, one should set the vmethods for save_preset() and delete_preset() to None. Applications can use is_editable() to check for that.

The default implementation supports presets located in a system directory, application specific directory and in the users home directory. When getting a list of presets individual presets are read and overlaid in 1) system, 2) application and 3) user order. Whenever an earlier entry is newer, the later entries will be updated. Since 1.8 you can also provide extra paths where to find presets through the GST_PRESET_PATH environment variable. Presets found in those paths will be considered as “app presets”.

Methods#

class Preset
delete_preset(name: str) → bool#

Delete the given preset.

Parameters:

name – preset name to remove

classmethod get_app_dir() → str | None#

Gets the directory for application specific presets if set by the application.

get_meta(name: str, tag: str) → Tuple[bool, str]#

Gets the value for an existing meta data tag. Meta data tag names can be something like e.g. “comment”. Returned values need to be released when done.

Parameters:

  • name – preset name

  • tag – meta data item name

get_preset_names() → list[str]#

Get a copy of preset names as a None terminated string array.

get_property_names() → list[str]#

Get a the names of the GObject properties that can be used for presets.

is_editable() → bool#

Check if one can add new presets, change existing ones and remove presets.

Added in version 1.6.

load_preset(name: str) → bool#

Load the given preset.

Parameters:

name – preset name to load

rename_preset(old_name: str, new_name: str) → bool#

Renames a preset. If there is already a preset by the new_name it will be overwritten.

Parameters:

  • old_name – current preset name

  • new_name – new preset name

save_preset(name: str) → bool#

Save the current object settings as a preset under the given name. If there is already a preset by this name it will be overwritten.

Parameters:

name – preset name to save

classmethod set_app_dir() → bool#

Sets an extra directory as an absolute path that should be considered when looking for presets. Any presets in the application dir will shadow the system presets.

set_meta(name: str, tag: str, value: str | None = None) → bool#

Sets a new value for an existing meta data item or adds a new item. Meta data tag names can be something like e.g. “comment”. Supplying None for the value will unset an existing value.

Parameters:

  • name – preset name

  • tag – meta data item name

  • value – new value

Virtual Methods#

class Preset
do_delete_preset(name: str) → bool#

Delete the given preset.

Parameters:

name – preset name to remove

do_get_meta(name: str, tag: str) → Tuple[bool, str]#

Gets the value for an existing meta data tag. Meta data tag names can be something like e.g. “comment”. Returned values need to be released when done.

Parameters:

  • name – preset name

  • tag – meta data item name

do_get_preset_names() → list[str]#

Get a copy of preset names as a None terminated string array.

do_get_property_names() → list[str]#

Get a the names of the GObject properties that can be used for presets.

do_load_preset(name: str) → bool#

Load the given preset.

Parameters:

name – preset name to load

do_rename_preset(old_name: str, new_name: str) → bool#

Renames a preset. If there is already a preset by the new_name it will be overwritten.

Parameters:

  • old_name – current preset name

  • new_name – new preset name

do_save_preset(name: str) → bool#

Save the current object settings as a preset under the given name. If there is already a preset by this name it will be overwritten.

Parameters:

name – preset name to save

do_set_meta(name: str, tag: str, value: str | None = None) → bool#

Sets a new value for an existing meta data item or adds a new item. Meta data tag names can be something like e.g. “comment”. Supplying None for the value will unset an existing value.

Parameters:

  • name – preset name

  • tag – meta data item name

  • value – new value