aboutsummaryrefslogtreecommitdiffstats
path: root/lv2/lv2plug.in/ns/ext/state
diff options
context:
space:
mode:
authorDavid Robillard <d@drobilla.net>2012-03-30 23:27:26 +0000
committerDavid Robillard <d@drobilla.net>2012-03-30 23:27:26 +0000
commit17c6df0bc3043c57d2c02c58284ec4794f656b3c (patch)
treee1729e4891aca09fe4a0f560618a74a8fc608833 /lv2/lv2plug.in/ns/ext/state
parent689d75259a7187b2cb6a592025f11bc7d3aa58a2 (diff)
downloadlv2-17c6df0bc3043c57d2c02c58284ec4794f656b3c.tar.xz
Fix screwy invalid ExtensionData definitions as classes (now matches how Feature is used).
Add status return codes to state methods for error handling.
Diffstat (limited to 'lv2/lv2plug.in/ns/ext/state')
-rw-r--r--lv2/lv2plug.in/ns/ext/state/manifest.ttl2
-rw-r--r--lv2/lv2plug.in/ns/ext/state/state.h34
-rw-r--r--lv2/lv2plug.in/ns/ext/state/state.ttl151
3 files changed, 105 insertions, 82 deletions
diff --git a/lv2/lv2plug.in/ns/ext/state/manifest.ttl b/lv2/lv2plug.in/ns/ext/state/manifest.ttl
index 84d1af0..94de219 100644
--- a/lv2/lv2plug.in/ns/ext/state/manifest.ttl
+++ b/lv2/lv2plug.in/ns/ext/state/manifest.ttl
@@ -4,5 +4,5 @@
<http://lv2plug.in/ns/ext/state>
a lv2:Specification ;
lv2:minorVersion 0 ;
- lv2:microVersion 6 ;
+ lv2:microVersion 8 ;
rdfs:seeAlso <state.ttl> .
diff --git a/lv2/lv2plug.in/ns/ext/state/state.h b/lv2/lv2plug.in/ns/ext/state/state.h
index 2f5af22..44e19cb 100644
--- a/lv2/lv2plug.in/ns/ext/state/state.h
+++ b/lv2/lv2plug.in/ns/ext/state/state.h
@@ -31,8 +31,8 @@
#define LV2_STATE_URI "http://lv2plug.in/ns/ext/state"
#define LV2_STATE_PREFIX LV2_STATE_URI "#"
-#define LV2_STATE__Interface LV2_STATE_PREFIX "Interface"
#define LV2_STATE__State LV2_STATE_PREFIX "State"
+#define LV2_STATE__interface LV2_STATE_PREFIX "interface"
#define LV2_STATE__makePath LV2_STATE_PREFIX "makePath"
#define LV2_STATE__mapPath LV2_STATE_PREFIX "mapPath"
#define LV2_STATE__state LV2_STATE_PREFIX "state"
@@ -95,10 +95,12 @@ typedef enum {
/** A status code for state functions. */
typedef enum {
- LV2_STATE_SUCCESS = 0, /**< Completed successfully. */
- LV2_STATE_ERR_UNKNOWN = 1, /**< Unknown error. */
- LV2_STATE_ERR_BAD_TYPE = 2, /**< Failed due to unsupported type. */
- LV2_STATE_ERR_BAD_FLAGS = 3 /**< Failed due to unsupported flags. */
+ LV2_STATE_SUCCESS = 0, /**< Completed successfully. */
+ LV2_STATE_ERR_UNKNOWN = 1, /**< Unknown error. */
+ LV2_STATE_ERR_BAD_TYPE = 2, /**< Failed due to unsupported type. */
+ LV2_STATE_ERR_BAD_FLAGS = 3, /**< Failed due to unsupported flags. */
+ LV2_STATE_ERR_NO_FEATURE = 4, /**< Failed due to missing features. */
+ LV2_STATE_ERR_NO_PROPERTY = 5 /**< Failed due to missing property. */
} LV2_State_Status;
/**
@@ -171,7 +173,7 @@ typedef const void* (*LV2_State_Retrieve_Function)(
LV2 Plugin State Interface.
When the plugin's extension_data is called with argument
- LV2_STATE__Interface, the plugin MUST return an LV2_State_Interface
+ LV2_STATE__interface, the plugin MUST return an LV2_State_Interface
structure, which remains valid for the lifetime of the plugin.
The host can use the contained function pointers to save and restore the
@@ -223,11 +225,11 @@ typedef struct _LV2_State_Interface {
care to do so in such a way that a concurrent call to save() will save a
consistent representation of plugin state for a single instant in time.
*/
- void (*save)(LV2_Handle instance,
- LV2_State_Store_Function store,
- LV2_State_Handle handle,
- uint32_t flags,
- const LV2_Feature *const * features);
+ LV2_State_Status (*save)(LV2_Handle instance,
+ LV2_State_Store_Function store,
+ LV2_State_Handle handle,
+ uint32_t flags,
+ const LV2_Feature *const * features);
/**
Restore plugin state using a host-provided @p retrieve callback.
@@ -254,11 +256,11 @@ typedef struct _LV2_State_Interface {
LV2. This means it MUST NOT be called concurrently with any other
function on the same plugin instance.
*/
- void (*restore)(LV2_Handle instance,
- LV2_State_Retrieve_Function retrieve,
- LV2_State_Handle handle,
- uint32_t flags,
- const LV2_Feature *const * features);
+ LV2_State_Status (*restore)(LV2_Handle instance,
+ LV2_State_Retrieve_Function retrieve,
+ LV2_State_Handle handle,
+ uint32_t flags,
+ const LV2_Feature *const * features);
} LV2_State_Interface;
diff --git a/lv2/lv2plug.in/ns/ext/state/state.ttl b/lv2/lv2plug.in/ns/ext/state/state.ttl
index 6bc884b..2d12d08 100644
--- a/lv2/lv2plug.in/ns/ext/state/state.ttl
+++ b/lv2/lv2plug.in/ns/ext/state/state.ttl
@@ -30,8 +30,8 @@
doap:shortdesc "An interface for LV2 plugins to save and restore state." ;
doap:license <http://opensource.org/licenses/isc> ;
doap:release [
- doap:revision "0.6" ;
- doap:created "2012-03-03" ;
+ doap:revision "0.8" ;
+ doap:created "2012-03-30" ;
dcs:blame <http://drobilla.net/drobilla#me>
] ;
doap:developer <http://lv2plug.in/ns/people#paniq> ,
@@ -68,7 +68,7 @@ key:value pair is called a <q>property</q>.</p>
dynamic dictionary data structure available.</li>
</ul>
-<p>To implement state, the plugin provides a state:Interface to the host. To
+<p>To implement state, the plugin provides a state:interface to the host. 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 property. The host is free to implement property storage and retrieval
@@ -85,15 +85,15 @@ is simply a C string.</p>
<p>Plugins may need to refer to existing files (e.g. loaded samples) in their
state. This is done by storing the file's path as a property just like any
other value. However, there are some rules which MUST be followed when storing
-paths, see <a href="#mapPath">state:mapPath</a> for details. Plugins MUST use
-the type <a href="http://lv2plug.in/ns/ext/atom#Path">atom:Path</a> for all
-paths in their state.</p>
+paths, see state:mapPath for details. Plugins MUST use the type <a
+href="http://lv2plug.in/ns/ext/atom#Path">atom:Path</a> for all paths in their
+state.</p>
<p>Plugins are strongly encouraged to avoid creating files, instead storing all
state as properties. However, occasionally the ability to create files is
-necessary. To make this possible, the host can provide the feature <a
-href="#makePath">state:makePath</a> which allocates paths for plugin-created
-files. Plugins MUST NOT create files in any other locations.</p>
+necessary. To make this possible, the host can provide the feature
+state:makePath which allocates paths for plugin-created files. Plugins MUST
+NOT create files in any other locations.</p>
<h3>Plugin Code Example</h3>
@@ -104,20 +104,24 @@ files. Plugins MUST NOT create files in any other locations.</p>
*/
#define NS_MY "http://example.org/myplugin/schema#"
-LV2_Handle my_instantiate(...)
+#define DEFAULT_GREETING "Hello"
+
+LV2_Handle
+my_instantiate(...)
{
MyPlugin* plugin = ...;
plugin->uris.atom_String = map_uri(LV2_ATOM__String);
plugin->uris.my_greeting = map_uri(NS_MY "greeting");
- plugin->state.greeting = strdup("Hello"); // Default value
+ plugin->state.greeting = strdup(DEFAULT_GREETING);
return plugin;
}
-void my_save(LV2_Handle instance,
- LV2_State_Store_Function store,
- LV2_State_Handle handle,
- uint32_t flags,
- const LV2_Feature *const * features)
+LV2_State_Status
+my_save(LV2_Handle instance,
+ LV2_State_Store_Function store,
+ LV2_State_Handle handle,
+ uint32_t flags,
+ const LV2_Feature *const * features)
{
MyPlugin* plugin = (MyPlugin*)instance;
const char* greeting = plugin->state.greeting;
@@ -128,13 +132,16 @@ void my_save(LV2_Handle instance,
strlen(greeting) + 1, // Careful! Need space for terminator
plugin->uris.atom_String,
LV2_STATE_IS_POD | LV2_STATE_IS_PORTABLE);
+
+ return LV2_STATUS_SUCCESS;
}
-void my_restore(LV2_Handle instance,
- LV2_State_Retrieve_Function retrieve,
- LV2_State_Handle handle,
- uint32_t flags,
- const LV2_Feature *const * features)
+LV2_State_Status
+my_restore(LV2_Handle instance,
+ LV2_State_Retrieve_Function retrieve,
+ LV2_State_Handle handle,
+ uint32_t flags,
+ const LV2_Feature *const * features)
{
MyPlugin* plugin = (MyPlugin*)instance;
@@ -148,14 +155,17 @@ void my_restore(LV2_Handle instance,
free(plugin->state->greeting);
plugin->state->greeting = strdup(greeting);
} else {
- plugin->state->greeting = strdup("Hello");
+ plugin->state->greeting = strdup(DEFAULT_GREETING);
}
+
+ return LV2_STATUS_SUCCESS;
}
-const void* my_extension_data(const char* uri)
+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)) {
+ if (!strcmp(uri, LV2_STATE__interface)) {
return &amp;state_iface;
}
}
@@ -164,12 +174,13 @@ const void* my_extension_data(const char* uri)
<h3>Host Code Example</h3>
<pre class="c-code">
-int store_callback(LV2_State_Handle handle,
- uint32_t key,
- const void* value,
- size_t size,
- uint32_t type,
- uint32_t flags)
+LV2_State_Status
+store_callback(LV2_State_Handle handle,
+ uint32_t key,
+ const void* value,
+ size_t size,
+ uint32_t type,
+ uint32_t flags)
{
if ((flags &amp; LV2_STATE_IS_POD)) {
/* We only care about POD since we're keeping state in memory only.
@@ -183,9 +194,10 @@ int store_callback(LV2_State_Handle handle,
}
}
-Map get_plugin_state(LV2_Handle instance)
+Map
+get_plugin_state(LV2_Handle instance)
{
- LV2_State* state = instance.extension_data(LV2_STATE__Interface);
+ LV2_State* state = instance.extension_data(LV2_STATE__interface);
Map state_map;
/** Request a fast/native/POD save, since we're just copying in memory */
state.save(instance, store_callback, &amp;state_map,
@@ -209,26 +221,36 @@ instance, at least well enough that saving and restoring will yield an
plugin instance.</li>
</ul>
-<p>The recommended way to add new functionality that may affect state is to
-simply define it in terms of properties. For example, instead of defining a
-new set of commands, define properties whose values can be set appropriately.
-This provides persistence <q>for free</q>, since rather than having to define a
-set of commands <em>and</em> a set of properties for storing their effects,
-only the properties need to be defined.</p>
-
-<p>This <q>property principle</q> is summed up in the phrase: <q>Don't
-stop; set playing to false</q>.</p>
+<h3>The <q>Property Principle</q></h3>
+
+<p>The main benefit of this meaningful state model is that it can double as a
+plugin control/query mechanism. For plugins that require more advanced control
+than simple control ports, instead of defining a set of commands, define
+properties whose values can be set appropriately. This provides both a way to
+control and save that state <q>for free</q>, since there is no need to define
+commands <em>and</em> a set of properties for storing their effects. In
+particular, this is a good way for UIs to achieve more advanced control of
+plugins.</p>
+
+<p>This <q>property principle</q> is summed up in the phrase:
+<q>Don't stop; set playing to false</q>.</p>
+
+<p>This extension does not define a dynamic mechanism for state access and
+manipulation. The <a href="http://lv2plug.in/ns/ext/patch">LV2 Patch</a>
+extension defines a generic set of messages which can be used to access or
+manipulate properties, and the <a href="http://lv2plug.in/ns/ext/atom">LV2
+Atom</a> extension defines a port type and data container capable of
+transmitting those messages.</p>
""" .
-state:Interface
- a rdfs:Class ;
- rdfs:subClassOf lv2:ExtensionData ;
+state:interface
+ a lv2:ExtensionData ;
lv2:documentation """
<p>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 URI
-LV2_STATE__Interface.</p>
+LV2_STATE__interface.</p>
<p>The plugin data file should describe this like so:</p>
<pre class="turtle-code">
@@ -236,7 +258,7 @@ LV2_STATE__Interface.</p>
&lt;plugin&gt;
a lv2:Plugin ;
- lv2:extensionData state:Interface .
+ lv2:extensionData state:interface .
</pre>
""" .
@@ -245,9 +267,9 @@ state:State
rdfs:label "Plugin Instance State" ;
lv2:documentation """
<p>A state dictionary. This type should be used wherever instance state is
-described in RDF, or any other context that uses type URIs. The properties of
-a resource with this type correspond directly to the properties of the state
-dictionary (except the property that states it has this type).</p>
+described. The properties of a resource with this type correspond directly to
+the properties of the state dictionary (except the property that states it has
+this type).</p>
""" .
state:state
@@ -255,13 +277,13 @@ state:state
rdfs:label "State" ;
rdfs:range state:State ;
lv2:documentation """
-<p>The state of this plugin instance, or similar resource. This property may
-be used anywhere a state needs to be described, for example:</p>
+<p>The state of this instance. This property may be used anywhere a state
+needs to be described, for example:</p>
<pre class="turtle-code">
@prefix eg: &lt;http://example.org/&gt; .
-&lt;plugininstance&gt;
+&lt;plugin-instance&gt;
state:state [
eg:somekey "some value" ;
eg:someotherkey "some other value" ;
@@ -313,24 +335,23 @@ state:makePath
lv2:documentation """
<p>This feature allows plugins to create new files and/or directories. To
support this feature the host passes an LV2_Feature with URI
-LV2_STATE__makePath and data pointed to an LV2_State_Make_Path to the
-plugin. The host may make this feature available only during save by passing
-it to LV2_State_Interface::save(), or available any time by passing it to
+LV2_STATE__makePath and data pointed to an LV2_State_Make_Path to the plugin.
+The host may make this feature available only during save by passing it to
+LV2_State_Interface::save(), or available any time by passing it to
LV2_Descriptor::instantiate(). If passed to LV2_State_Interface::save(), the
feature MUST NOT be used beyond the scope of that call.</p>
-<p>The plugin is guaranteed a hierarchial namespace unique to that plugin
+<p>The plugin is guaranteed a hierarchical namespace unique to that plugin
instance, and may expect the returned path to have the requested path as a
suffix. There is <em>one</em> such namespace, even if the feature is passed to
-both LV2_Descriptor::instantiate() <em>and</em>
-LV2_State_Interface::save(). Beyond this, the plugin MUST NOT make any
-assumptions about the returned paths.</p>
+both LV2_Descriptor::instantiate() <em>and</em> LV2_State_Interface::save().
+Beyond this, the plugin MUST NOT make any assumptions about the returned
+paths.</p>
-<p>Like any other paths, the plugin MUST map these paths using <a
-href="#mapPath">state:mapPath</a> before storing them in state. The plugin
-MUST NOT assume these paths will be available across a save/restore otherwise,
-i.e. only mapped paths saved to state are persistent, any other created paths
-are temporary.</p>
+<p>Like any other paths, the plugin MUST map these paths using state:mapPath
+before storing them in state. The plugin MUST NOT assume these paths will be
+available across a save/restore otherwise, i.e. only mapped paths saved to
+state are persistent, any other created paths are temporary.</p>
<p>For example, a plugin may create a file in a subdirectory like so:</p>
@@ -339,7 +360,7 @@ char* save_myfile(LV2_State_Make_Path* make_path)
{
char* path = make_path->path(make_path->handle, "foo/bar/myfile.txt");
FILE* myfile = fopen(path, 'w');
- fprintf(myfile, "Hello");
+ fprintf(myfile, "I am some data");
fclose(myfile);
return path;
}