From eb43c8896480114b224755e824fae2e2f7485256 Mon Sep 17 00:00:00 2001 From: David Robillard Date: Mon, 21 Nov 2011 01:36:00 +0000 Subject: Move ns to lv2/ns so repository top level can be used as an include dir directly. --- ns/ext/state/state.ttl | 231 ------------------------------------------------- 1 file changed, 231 deletions(-) delete mode 100644 ns/ext/state/state.ttl (limited to 'ns/ext/state/state.ttl') diff --git a/ns/ext/state/state.ttl b/ns/ext/state/state.ttl deleted file mode 100644 index c79188e..0000000 --- a/ns/ext/state/state.ttl +++ /dev/null @@ -1,231 +0,0 @@ -# LV2 State Extension -# Copyright 2010-2011 David Robillard -# Copyright 2010 Leonard Ritter -# -# Permission to use, copy, modify, and/or distribute this software for any -# purpose with or without fee is hereby granted, provided that the above -# copyright notice and this permission notice appear in all copies. -# -# THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES -# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF -# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR -# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES -# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN -# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF -# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. - -@prefix state: . -@prefix doap: . -@prefix foaf: . -@prefix lv2: . -@prefix rdf: . -@prefix rdfs: . - - - a lv2:Specification ; - doap:name "LV2 State" ; - doap:shortdesc "An interface for LV2 plugins to save and restore state." ; - doap:license ; - doap:release [ - doap:revision "0.2" ; - doap:created "2011-11-14" - ] ; - doap:developer [ - a foaf:Person ; - foaf:name "Leonard Ritter" ; - foaf:homepage ; - ] ; - doap:maintainer [ - a foaf:Person ; - foaf:name "David Robillard" ; - foaf:homepage ; - rdfs:seeAlso - ] ; - lv2:documentation """ -

This extension provides a mechanism for plugins to save and restore state -across instances, allowing hosts to save, restore, clone, or take a snapshot of -a plugin instance's state at any point in time. The intention is for a plugin -instance's state to be completely described by port values (as with all -LV2 plugins) and a simple dictionary.

- -

The state described by this extension is conceptually a single -key/value dictionary, where keys are URIDs and values are type-tagged blobs of -any type. The plugin provides an LV2_State_Interface for working with this -state. To save or restore, the host calls LV2_State_Interface::save() or -LV2_State_Interface::restore(), passing a callback to be used for handling a -single key/value pair. The host is free to implement saving and restoring in -any way; the actual mechanism is completely abstract from the plugin's -perspective.

- -

Because state is a simple dictionary, hosts and plugins can work with it -easily from many languages and protocols. Keys are URIDs for performance -reasons as well as RDF compatibility, which makes it simple to serialise state -in many formats (e.g. any RDF syntax, JSON, XML, key/value databases such as -BDB, etc.). In particular, state can be elegantly described in a plugin's -Turtle description, which is useful for e.g. presets or default state. -Specific keys may be described in Turtle on the fly or in extensions, -allowing plugins to use common well-defined keys.

- -

This extension defines a conceptual model of state and a mechanism for -saving and restoring it, but no interface for manipulating it dynamically. -While no such mechanism is defined here, dynamic control of plugins SHOULD be -achieved by generic manipulations of the same conceptual state dictionary used -by this extension (e.g. plugin->set(key, value)). Accordingly, -plugins SHOULD use meaningful and well-defined keys wherever possible.

- -

In pseudo code, a typical use case in a plugin is:

-
-#define NS_EG   "http://example.org/"
-#define NS_ATOM "http://lv2plug.in/ns/ext/atom#"
-
-LV2_Handle my_instantiate(...)
-{
-    MyPlugin* plugin = ...;
-    plugin->uris.atom_String = map_uri(NS_ATOM "String");
-    plugin->uris.eg_greeting = map_uri(NS_EG "greeting");
-    plugin->state.greeting   = strdup("Hello");
-    return plugin;
-}
-
-void my_save(LV2_Handle                 instance,
-             LV2_State_Store_Function   store,
-             void*                      handle,
-             uint32_t                   flags,
-             const LV2_Feature *const * features)
-
-{
-    MyPlugin*   plugin   = (MyPlugin*)instance;
-    const char* greeting = plugin->state.greeting;
-
-    store(handle,
-          plugin->uris.eg_greeting,
-          greeting,
-          strlen(greeting) + 1,
-          plugin->uris.atom_String,
-          LV2_STATE_IS_POD | LV2_STATE_IS_PORTABLE);
-}
-
-void my_restore(LV2_Handle                  instance,
-                LV2_State_Retrieve_Function retrieve,
-                void*                       handle,
-                uint32_t                    flags,
-                const LV2_Feature *const *   features)
-{
-    MyPlugin* plugin = (MyPlugin*)instance;
-
-    size_t      size;
-    uint32_t    type;
-    uint32_t    flags;
-    const char* greeting = retrieve(handle,
-                                    plugin->uris.eg_greeting,
-                                    &size,
-                                    &type,
-                                    &flags);
-
-    if (greeting) {
-        free(plugin->state->greeting);
-        plugin->state->greeting = strdup(greeting);
-    } else {
-        plugin->state->greeting = strdup("Hello");
-    }
-}
-
-const void* my_extension_data(const char* uri)
-{
-    static const LV2_State_Interface state_iface = { my_save, my_restore };
-    if (!strcmp(uri, LV2_STATE_INTERFACE_URI)) {
-        return &state_iface;
-    }
-}
-
- -

Similarly, a typical use case in a host is:

-
-int store_callback(void*       handle,
-                   uint32_t    key,
-                   const void* value,
-                   size_t      size,
-                   uint32_t    type,
-                   uint32_t    flags)
-{
-    if ((flags & LV2_STATE_IS_POD)) {
-        /* We only care about POD since we're keeping state in memory only.
-           If this was for disk or network storage/transmission,
-           LV2_STATE_IS_PORTABLE would have to be checked as well.
-        */
-        Map* state_map = (Map*)handle;
-        state_map->insert(key, Value(copy(value), size, type, pod));
-        return 0;
-    } else {
-        return 1; /* Non-POD events are unsupported. */
-    }
-}
-
-Map get_plugin_state(LV2_Handle instance)
-{
-    LV2_State* state = instance.extension_data("http://lv2plug.in/ns/ext/state");
-    Map state_map;
-    /** Request a fast/native/POD save, since we're just copying in memory */
-    state.save(instance, store_callback, &state_map,
-               LV2_STATE_IS_POD|LV2_STATE_IS_NATIVE);
-    return state_map;
-}
-
-""" . - -state:Interface - a rdfs:Class ; - rdfs:subClassOf lv2:ExtensionData ; - lv2:documentation """ -

A structure (LV2_State_Interface) which contains functions to be called by -the host to save and restore state. In order to support this extension, the -plugin must return a valid LV2_State_Interface from -LV2_Descriptor::extension_data() when it is called with -LV2_STATE_INTERFACE_URI.

- -

The plugin data file should describe this like so:

-
-@prefix state: <http://lv2plug.in/ns/ext/state#> .
-
-<plugin>
-    a lv2:Plugin ;
-    lv2:extensionData state:Interface .
-
-""" . - -state:InstanceState - a rdfs:Class ; - rdfs:label "Plugin Instance State" ; - rdfs:comment """ -This class is used to express a plugin instance's state in RDF. The key/value -properties of the instance form the predicate/object (respectively) of triples -with a state:InstanceState as the subject (see state:instanceState for an -example). This may be used wherever it is useful to express a plugin instance's -state in RDF (e.g. for serialisation, storing in a model, or transmitting over -a network). Note that this class is provided because it may be useful for -hosts, plugins, or extensions that work with instance state, but its use is not -required to support the LV2 State extension. -""" . - -state:instanceState - a rdf:Property ; - rdfs:range state:InstanceState ; - lv2:documentation """ -

Predicate to relate a plugin instance to an InstanceState. This may be used -wherever the state of a particular plugin instance needs to be represented. -Note that the domain of this property is unspecified, since LV2 does not define -any RDF class for plugin instance. This predicate may be used wherever it makes -sense to do so, e.g.:

-
-@prefix eg: <http://example.org/> .
-
-<plugininstance> state:instanceState [
-    eg:somekey "some value" ;
-    eg:someotherkey "some other value" ;
-    eg:favourite-number 2
-] .
-
-

Note that this property is provided because it may be useful for hosts, -plugins, or extensions that work with instance state, but its use is not -required to support the LV2 State extension.

-""" . -- cgit v1.2.1