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/*
Copyright (C) 2011-2014 David Robillard
Copyright (C) 2013 Paul Davis
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @file jack/metadata.h
* @ingroup publicheader
* @brief JACK Metadata API
*
*/
#ifndef __jack_metadata_h__
#define __jack_metadata_h__
#include <jack/types.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup Metadata Metadata API.
* @{
*/
/**
* A single property (key:value pair).
*
* Although there is no semantics imposed on metadata keys and values, it is
* much less useful to use it to associate highly structured data with a port
* (or client), since this then implies the need for some (presumably
* library-based) code to parse the structure and be able to use it.
*
* The real goal of the metadata API is to be able to tag ports (and clients)
* with small amounts of data that is outside of the core JACK API but
* nevertheless useful.
*/
typedef struct {
/** The key of this property (URI string). */
const char* key;
/** The property value (null-terminated string). */
const char* data;
/**
* Type of data, either a MIME type or URI.
*
* If type is NULL or empty, the data is assumed to be a UTF-8 encoded
* string (text/plain). The data is a null-terminated string regardless of
* type, so values can always be copied, but clients should not try to
* interpret values of an unknown type.
*
* Example values:
* - image/png;base64 (base64 encoded PNG image)
* - http://www.w3.org/2001/XMLSchema#int (integer)
*
* Official types are preferred, but clients may use any syntactically
* valid MIME type (which start with a type and slash, like "text/...").
* If a URI type is used, it must be a complete absolute URI
* (which start with a scheme and colon, like "http:").
*/
const char* type;
} jack_property_t;
/**
* Set a property on @p subject.
*
* See the above documentation for rules about @p subject and @p key.
* @param subject The subject to set the property on.
* @param key The key of the property.
* @param value The value of the property.
* @param type The type of the property. See the discussion of
* types in the definition of jack_property_t above.
* @return 0 on success.
*/
int
jack_set_property(jack_client_t*,
jack_uuid_t subject,
const char* key,
const char* value,
const char* type);
/**
* Get a property on @p subject.
*
* @param subject The subject to get the property from.
* @param key The key of the property.
* @param value Set to the value of the property if found, or NULL otherwise.
* The caller must free this value with jack_free().
* @param type The type of the property if set, or NULL. See the discussion
* of types in the definition of jack_property_t above.
* If non-null, the caller must free this value with jack_free().
*
* @return 0 on success, -1 if the @p subject has no @p key property.
*/
int
jack_get_property(jack_uuid_t subject,
const char* key,
char** value,
char** type);
/**
* A description of a subject (a set of properties).
*/
typedef struct {
jack_uuid_t subject; /**< Subject being described. */
uint32_t property_cnt; /**< Number of elements in "properties". */
jack_property_t* properties; /**< Array of properties. */
uint32_t property_size; /**< Private, do not use. */
} jack_description_t;
/**
* Free a description.
*
* @param desc a jack_description_t whose associated memory will all be released
* @param free_description_itself if non-zero, then @param desc will also be passed to free()
*/
void
jack_free_description (jack_description_t* desc, int free_description_itself);
/**
* Get a description of @p subject.
* @param subject The subject to get all properties of.
* @param desc Set to the description of subject if found, or NULL otherwise.
* The caller must free this value with jack_free_description().
* @return the number of properties, -1 if no @p subject with any properties exists.
*/
int
jack_get_properties (jack_uuid_t subject,
jack_description_t* desc);
/**
* Get descriptions for all subjects with metadata.
* @param descs Set to an array of descriptions.
* The caller must free each of these with jack_free_description(),
* and the array itself with jack_free().
* @return the number of descriptions, or -1 on error.
*/
int
jack_get_all_properties (jack_description_t** descs);
/**
* Remove a single property on a subject.
*
* @param client The JACK client making the request to remove the property.
* @param subject The subject to remove the property from.
* @param key The key of the property to be removed.
*
* @return 0 on success, -1 otherwise
*/
int jack_remove_property (jack_client_t* client, jack_uuid_t subject, const char* key);
/**
* Remove all properties on a subject.
*
* @param client The JACK client making the request to remove some properties.
* @param subject The subject to remove all properties from.
*
* @return a count of the number of properties removed, or -1 on error.
*/
int jack_remove_properties (jack_client_t* client, jack_uuid_t subject);
/**
* Remove all properties.
*
* WARNING!! This deletes all metadata managed by a running JACK server.
* Data lost cannot be recovered (though it can be recreated by new calls
* to jack_set_property()).
*
* @param client The JACK client making the request to remove all properties
*
* @return 0 on success, -1 otherwise
*/
int jack_remove_all_properties (jack_client_t* client);
typedef enum {
PropertyCreated,
PropertyChanged,
PropertyDeleted
} jack_property_change_t;
/**
* Prototype for the client supplied function that is called by the
* engine anytime a property or properties have been modified.
*
* Note that when the key is empty, it means all properties have been
* modified. This is often used to indicate that the removal of all keys.
*
* @param subject The subject the change relates to, this can be either a client or port
* @param key The key of the modified property (URI string)
* @param change Wherever the key has been created, changed or deleted
* @param arg pointer to a client supplied structure
*/
typedef void (*JackPropertyChangeCallback)(jack_uuid_t subject,
const char* key,
jack_property_change_t change,
void* arg);
/**
* Arrange for @p client to call @p callback whenever a property is created,
* changed or deleted.
*
* @param client the JACK client making the request
* @param callback the function to be invoked when a property change occurs
* @param arg the argument to be passed to @param callback when it is invoked
*
* @return 0 success, -1 otherwise.
*/
int jack_set_property_change_callback (jack_client_t* client,
JackPropertyChangeCallback callback,
void* arg);
/**
* A value that identifies what the hardware port is connected to (an external
* device of some kind). Possible values might be "E-Piano" or "Master 2 Track".
*/
extern const char* JACK_METADATA_CONNECTED;
/**
* The supported event types of an event port.
*
* This is a kludge around Jack only supporting MIDI, particularly for OSC.
* This property is a comma-separated list of event types, currently "MIDI" or
* "OSC". If this contains "OSC", the port may carry OSC bundles (first byte
* '#') or OSC messages (first byte '/'). Note that the "status byte" of both
* OSC events is not a valid MIDI status byte, so MIDI clients that check the
* status byte will gracefully ignore OSC messages if the user makes an
* inappropriate connection.
*/
extern const char* JACK_METADATA_EVENT_TYPES;
/**
* A value that should be shown when attempting to identify the
* specific hardware outputs of a client. Typical values might be
* "ADAT1", "S/PDIF L" or "MADI 43".
*/
extern const char* JACK_METADATA_HARDWARE;
/**
* A value with a MIME type of "image/png;base64" that is an encoding of an
* NxN (with 32 < N <= 128) image to be used when displaying a visual
* representation of that client or port.
*/
extern const char* JACK_METADATA_ICON_LARGE;
/**
* The name of the icon for the subject (typically client).
*
* This is used for looking up icons on the system, possibly with many sizes or
* themes. Icons should be searched for according to the freedesktop Icon
*
* Theme Specification:
* https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html
*/
extern const char* JACK_METADATA_ICON_NAME;
/**
* A value with a MIME type of "image/png;base64" that is an encoding of an
* NxN (with N <=32) image to be used when displaying a visual representation
* of that client or port.
*/
extern const char* JACK_METADATA_ICON_SMALL;
/**
* Order for a port.
*
* This is used to specify the best order to show ports in user interfaces.
* The value MUST be an integer. There are no other requirements, so there may
* be gaps in the orders for several ports. Applications should compare the
* orders of ports to determine their relative order, but must not assign any
* other relevance to order values.
*
* It is encouraged to use http://www.w3.org/2001/XMLSchema#int as the type.
*/
extern const char* JACK_METADATA_ORDER;
/**
* A value that should be shown to the user when displaying a port to the user,
* unless the user has explicitly overridden that a request to show the port
* name, or some other key value.
*/
extern const char* JACK_METADATA_PRETTY_NAME;
/**
*/
extern const char* JACK_METADATA_PORT_GROUP;
/**
* The type of an audio signal.
*
* This property allows audio ports to be tagged with a "meaning". The value
* is a simple string. Currently, the only type is "CV", for "control voltage"
* ports. Hosts SHOULD be take care to not treat CV ports as audible and send
* their output directly to speakers. In particular, CV ports are not
* necessarily periodic at all and may have very high DC.
*/
extern const char* JACK_METADATA_SIGNAL_TYPE;
/**
* @}
*/
#ifdef __cplusplus
} /* namespace */
#endif
#endif /* __jack_metadata_h__ */