This extension defines a facility for options
, which are values the host
passes to a plugin or UI at run time.
There are two facilities for passing options to an instance: options allows passing options at instantiation time, and the interface interface allows options to be dynamically set and retrieved after instantiation.
Note that this extension is only for allowing hosts to configure plugins, and
is not a live
control mechanism. For real-time control, use event-based
control via an atom:AtomPort with an atom:Sequence buffer.
Instances may indicate they require an option with the requiredOption property, or that they optionally support an option with the supportedOption property.
Index
Properties
requiredOption
Property| Label | required option |
|---|---|
| Range | rdf:Property |
| Type | Object Property |
An option required by the instance to function at all.
The host MUST pass a value for the specified option via options during instantiation.
Note that use of this property may reduce the number of compatible hosts. Wherever possible, it is better to list options with supportedOption and fall back to a reasonable default value if it is not provided.
supportedOption
Property| Label | supported option |
|---|---|
| Range | rdf:Property |
| Type | Object Property |
An option supported or by the instance.
The host SHOULD provide a value for the specified option if one is known, or provide the user an opportunity to specify one if possible.
Instances
interface
Instance| Label | interface |
|---|---|
| Type | lv2:ExtensionData |
An interface for dynamically setting and getting options.
An interface (LV2_Options_Interface) for dynamically setting and getting
options. Note that this is intended for use by the host for configuring
plugins only, and is not a live
plugin control mechanism.
The plugin data file should advertise this interface like so:
@prefix opts: <http://lv2plug.in/ns/ext/options#> .
<plugin>
a lv2:Plugin ;
lv2:extensionData opts:interface .
options
Instance| Label | options |
|---|---|
| Type | lv2:Feature |
The feature used to provide options to an instance.
To implement this feature, hosts MUST pass an LV2_Feature to the appropriate
instantiate method with this URI and data pointed to an array of
LV2_Options_Option terminated by an element with both key and value set to
zero. The instance should cast this data pointer to const
LV2_Options_Option* and scan the array for any options of interest. The
instance MUST NOT modify the options array in any way.
Note that requiring this feature may reduce the number of compatible hosts. Unless some options are strictly required by the instance, this feature SHOULD be listed as an lv2:optionalFeature.
A value for a static option passed to an instance.
It is not required for a property to explicitly be an Option in order to be used as such. However, properties which are primarily intended for use as options, or are at least particularly useful as options, should be explicitly given this type for documentation purposes, and to assist hosts in discovering option definitions.