Updates LV2 and LV2 UI specs.

git-svn-id: http://svn.drobilla.net/lad/slv2@762 a436a847-0d15-0410-975c-d299462d15a1

7 files changed, 413 insertions, 272 deletions

diff --git a/slv2/Makefile.am b/slv2/Makefile.am
index f090e22..8deb4db 100644
--- a/slv2/Makefile.am
+++ b/slv2/Makefile.am
@@ -3,7 +3,7 @@ slv2includedir = $(includedir)/slv2
 slv2include_HEADERS = \
 	gui.h \
 	lv2.h \
-	lv2-gtk2gui.h \
+	lv2_gui.h \
 	plugin.h \
 	pluginclass.h \
 	pluginclasses.h \
diff --git a/slv2/lv2-gtk2gui.h b/slv2/lv2-gtk2gui.h
deleted file mode 100644
index ae05c16..0000000
--- a/slv2/lv2-gtk2gui.h
+++ /dev/null
@@ -1,212 +0,0 @@
-/************************************************************************
- *
- * GTK2 in-process UI extension for LV2
- *
- * Copyright (C) 2006 Lars Luthman <lars.luthman@gmail.com>
- * 
- * Based on lv2.h, which is 
- *
- * Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis, Stefan
- * Westerfeld
- * Copyright (C) 2006 Steve Harris, Dave Robillard.
- *
- * This header 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 header 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 library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
- * USA.
- *
- ***********************************************************************/
-
-/** @file
-    This extension defines an interface that can be used in LV2 plugins and
-    hosts to create GTK2 GUIs for plugins. The GUIs will be plugins that
-    will reside in shared object files in a LV2 bundle and be referenced in 
-    the RDF file using the triples
-<pre>    
-    <http://my.plugin> <http://ll-plugins.nongnu.org/lv2/ext/gtk2gui#gui> <http://my.plugingui>
-    <http://my.plugingui> <http://ll-plugins.nongnu.org/lv2/ext/gtk2gui#binary> <mygui.so>
-</pre>
-    where <http://my.plugin> is the URI of the plugin, <http://my.plugingui> is
-    the URI of the plugin GUI and <mygui.so> is the relative URI to the shared 
-    object file. While it is possible to have the plugin GUI and the plugin in 
-    the same shared object file it is probably a good idea to keep them 
-    separate so that hosts that don't want GUIs don't have to load the GUI code.
-    
-    It's entirely possible to have multiple GUIs for the same plugin, or to have
-    the GUI for a plugin in a different bundle from the actual plugin - this
-    way people other than the plugin author can write plugin GUIs independently
-    without editing the original plugin bundle. If a GUI is in a separate bundle
-    the first triple above should be in that bundle's manifest.ttl file so that
-    hosts can find the GUI when scanning the manifests.
-    
-    Note that the process that loads the shared object file containing the GUI
-    code and the process that loads the shared object file containing the 
-    actual plugin implementation does not have to be the same. There are many
-    valid reasons for having the plugin and the GUI in different processes, or
-    even on different machines. This means that you can _not_ use singletons
-    and global variables and expect them to refer to the same objects in the
-    GUI and the actual plugin. The function callback interface defined in this
-    header is all you can expect to work.
-    
-    Since the LV2 specification itself allows for extensions that may add 
-    new types of data and configuration parameters that plugin authors may 
-    want to control with a GUI, this extension allows for meta-extensions that
-    can extend the interface between the GUI and the host. See the
-    instantiate() and extension_data() callback pointers for more details.
-    
-    Note that this extension is NOT a Host Feature. There is no way for a plugin
-    to know whether the host that loads it supports GUIs or not, and the plugin
-    must ALWAYS work without the GUI (although it may be rather useless unless
-    it has been configured using the GUI in a previous session).
-    
-    GUIs written to this specification do not need to be threadsafe - the 
-    functions defined below may only be called in the same thread as the GTK
-    main loop is running in.
-*/
-
-#ifndef LV2_GTK2GUI_H
-#define LV2_GTK2GUI_H
-
-#include "lv2.h"
-
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* The original header includes <gtk/gtkwidget.h>, but we don't want
-   libslv2 to depend on GTK+ so we forward declare the _GtkWidget struct
-   instead. */
-struct _GtkWidget;
-
-
-
-/** This handle indicates a particular instance of a GUI.
-    It is valid to compare this to NULL (0 for C++) but otherwise the 
-    host MUST not attempt to interpret it. The GUI plugin may use it to 
-    reference internal instance data. */
-typedef void* LV2UI_Handle;
-
-
-/** This handle indicates a particular plugin instance, provided by the host.
-    It is valid to compare this to NULL (0 for C++) but otherwise the 
-    GUI plugin MUST not attempt to interpret it. The host may use it to 
-    reference internal instance data. */
-typedef void* LV2UI_Controller;
-
-
-/** This is the type of the host-provided function that changes the value
-    of a control rate float input port in a plugin instance. A function
-    pointer of this type will be provided to the GUI by the host in the
-    instantiate() function. */
-typedef void (*LV2UI_Set_Control_Function)(LV2UI_Controller controller,
-                                           uint32_t         port,
-                                           float            value);
-
-
-typedef struct _LV2UI_Descriptor {
-  
-  /** The URI for this GUI (not for the plugin it controls). */
-  const char* URI;
-  
-  /** Create a new GUI object and return a handle to it. This function works
-      similarly to the instantiate() member in LV2_Descriptor, with the 
-      additions that the URI for the plugin that this GUI is for is passed
-      as a parameter, a function pointer and a controller handle are passed to
-      allow the plugin to change control port values in the plugin 
-      (control_function and controller) and a pointer to a GtkWidget pointer
-      is passed, which the GUI plugin should set to point to a newly created
-      widget which will be the main GUI for the plugin.
-      
-      The features array works like the one in the instantiate() member
-      in LV2_Descriptor, except that the URIs should be denoted with the triples
-      <pre>
-      <http://my.plugingui> <http://ll-plugins.nongnu.org/lv2/dev/gtk2gui#optionalFeature> <http://my.guifeature>
-      </pre>
-      or 
-      <pre>
-      <http://my.plugingui> <http://ll-plugins.nongnu.org/lv2/dev/gtk2gui#requiredFeature> <http://my.guifeature>
-      </pre>
-      in the RDF file, instead of the lv2:optionalFeature or lv2:requiredFeature
-      that is used by host features. These features are associated with the GUI,
-      not with the plugin - they are not actually LV2 Host Features, they just
-      use the same data structure.
-      
-      The same rules apply for these features as for normal host features -
-      if a feature is listed as required in the RDF file and the host does not
-      support it, it must not load the GUI.
-  */
-  LV2UI_Handle (*instantiate)(const struct _LV2UI_Descriptor* descriptor,
-                              const char*                     plugin_uri,
-                              const char*                     bundle_path,
-                              LV2UI_Set_Control_Function      control_function,
-                              LV2UI_Controller                controller,
-                              struct _GtkWidget**             widget,
-                              const LV2_Host_Feature**        features);
-
-  
-  /** Destroy the GUI object and the associated widget. 
-   */
-  void (*cleanup)(LV2UI_Handle  gui);
-  
-  /** Tell the GUI that a control port value has changed. This member may be
-      set to NULL if the GUI is not interested in control port changes. 
-  */
-  void (*set_control)(LV2UI_Handle   gui,
-                      uint32_t       port,
-                      float          value);
-  
-  /** Returns a data structure associated with an extension URI, for example
-      a struct containing additional function pointers. Avoid returning
-      function pointers directly since standard C++ has no valid way of
-      casting a void* to a function pointer. This member may be set to NULL
-      if the GUI is not interested in supporting any extensions. This is similar
-      to the extension_data() member in LV2_Descriptor.
-  */
-  void* (*extension_data)(LV2UI_Handle    gui,
-                          const char*     uri);
-
-} LV2UI_Descriptor;
-
-
-
-/** Accessing a plugin GUI.
-    
-    A plugin programmer must include a function called "lv2ui_descriptor"
-    with the following function prototype within the shared object
-    file. This function will have C-style linkage (if you are using
-    C++ this is taken care of by the 'extern "C"' clause at the top of
-    the file). This function will be accessed by the GUI host using the 
-    @c dlsym() function and called to get a LV2UI_UIDescriptor for the
-    wanted plugin.
-    
-    Just like lv2_descriptor(), this function takes an index parameter. The
-    index should only be used for enumeration and not as any sort of ID number -
-    the host should just iterate from 0 and upwards until the function returns
-    NULL, or a descriptor with an URI matching the one the host is looking for
-    is returned.
-*/
-const LV2UI_Descriptor* lv2ui_descriptor(uint32_t index);
-
-
-/** This is the type of the lv2ui_descriptor() function. */
-typedef const LV2UI_Descriptor* (*LV2UI_DescriptorFunction)(uint32_t index);
-
-
-
-#ifdef __cplusplus
-}
-#endif
-
-
-#endif
diff --git a/slv2/lv2.h b/slv2/lv2.h
index 1e73905..953c459 100644
--- a/slv2/lv2.h
+++ b/slv2/lv2.h
@@ -2,7 +2,7 @@
  * *** PROVISIONAL ***
  *
  * Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis,
- *                         Stefan Westerfeld
+ *                         Stefan Westerfeld.
  * Copyright (C) 2006-2007 Steve Harris, Dave Robillard.
  *
  * This header is free software; you can redistribute it and/or modify it
@@ -36,7 +36,7 @@ extern "C" {
 
 /** @file lv2.h
  *
- * Revision: 1.0beta4
+ * Revision: 1.0beta5
  *
  * == Overview ==
  *
@@ -54,18 +54,19 @@ extern "C" {
  * possible - the data file is mandatory.
  *
  * Plugins are expected to distinguish between control rate and audio
- * rate data. Plugins have 'ports' that are inputs or outputs for audio
- * or control data and each plugin is 'run' for a 'block' corresponding
- * to a short time interval measured in samples. Audio rate data is
- * communicated using arrays with one element per sample processed,
+ * rate data (or other types of data defined by extensions). Plugins have
+ * 'ports' that are inputs or outputs and each plugin is 'run' for a 'block'
+ * corresponding to a short time interval measured in samples. Audio rate
+ * data is communicated using arrays with one element per sample processed,
  * allowing a block of audio to be processed by the plugin in a single
  * pass. Control rate data is communicated using single values. Control
  * rate data has a single value at the start of a call to the 'run()'
  * function, and may be considered to remain this value for its duration.
- * Thus the 'control rate' is determined by the block size, controlled
- * by the host.  The plugin may assume that all its input and output
- * ports have been connected to the relevant data location (see the
- * 'connect_port()' function below) before it is asked to run.
+ * Thus the 'control rate' is determined by the block size, controlled by
+ * the host.  The plugin may assume that all its input and output ports have
+ * been connected to the relevant data location (see the 'connect_port()'
+ * function below) before it is asked to run, unless the port has been set
+ * 'connection optional' in the plugin's data file.
  *
  * Plugins will reside in shared object files suitable for dynamic linking
  * by dlopen() and family. The file will provide a number of 'plugin
@@ -84,14 +85,16 @@ extern "C" {
  * To facilitate this, the functions provided by a plugin are divided into
  * classes:
  *
- *  - Audio class:           run(), connect_port()
- *  - Instantiation class:   instantiate(), cleanup(), 
- *                           activate(), deactivate()
+ *  - Discovery class:     lv2_descriptor(), extension_data()
+ *  - Instantiation class: instantiate(), cleanup(), activate(), deactivate()
+ *  - Audio class:         run(), connect_port()
  *
  * Extensions to this specification which add new functions MUST declare in
  * which of these classes the functions belong, or define new classes for them.
  * The rules that hosts must follow are these:
  * 
+ *  - When a function from the Discovery class is running, no other 
+ *    functions in the same shared object file may run.
  *  - When a function from the Instantiation class is running for a plugin 
  *    instance, no other functions for that instance may run.
  *  - When a function is running for a plugin instance, no other 
@@ -100,9 +103,6 @@ extern "C" {
  * Any simultaneous calls that are not explicitly forbidden by these rules
  * are allowed. For example, a host may call run() for two different plugin 
  * instances simultaneously.
- *
- * The extension_data() function and the lv2_descriptor() function are never 
- * associated with any plugin instances and may be called at any time.
  */
 
 
@@ -127,14 +127,12 @@ typedef void * LV2_Handle;
  * feature the host has which the plugin may depend on.  This is to allow
  * extensions to the LV2 specification without causing any breakage.  The base
  * LV2 specification does not define any host features; hosts are not required
- * to use this facility.
- */
+ * to use this facility. */
 typedef struct _LV2_Host_Feature {
 	/** A globally unique, case-sensitive identifier for this feature.
 	 *
 	 * This MUST be defined in the specification of any LV2 extension which
-	 * defines a host feature.
-	 */
+	 * defines a host feature. */
 	const char * URI;
 
 	/** Pointer to arbitrary data.
@@ -144,8 +142,7 @@ typedef struct _LV2_Host_Feature {
 	 * specification makes no restrictions on the contents of this data.
 	 * The data here MUST be cleary defined by the LV2 extension which defines
 	 * this feature.
-	 * If no data is required, this may be set to NULL.
-	 */
+	 * If no data is required, this may be set to NULL. */
 	void * data;
 } LV2_Host_Feature;
 
@@ -195,10 +192,10 @@ typedef struct _LV2_Descriptor {
 	 * Note that instance initialisation should generally occur in
 	 * activate() rather than here.  If a host calls instantiate, it MUST
 	 * call cleanup() at some point in the future. */
-	LV2_Handle (*instantiate)(const struct _LV2_Descriptor *  Descriptor,
-	                          double                          SampleRate,
-	                          const char *                    BundlePath,
-	                          const LV2_Host_Feature *const * HostFeatures);
+	LV2_Handle (*instantiate)(const struct _LV2_Descriptor *  descriptor,
+	                          double                          sample_rate,
+	                          const char *                    bundle_path,
+	                          const LV2_Host_Feature *const * host_features);
 
 	/** Function pointer that connects a port on a plugin instance to a memory
 	 * location where the block of data for the port will be read/written.
@@ -231,9 +228,9 @@ typedef struct _LV2_Descriptor {
 	 * If the plugin has the property lv2:hardRTCapable then there are 
 	 * various things that the plugin MUST NOT do within the connect_port()
 	 * function (see lv2.ttl). */
-	void (*connect_port)(LV2_Handle Instance,
-	                     uint32_t   Port,
-	                     void *     DataLocation);
+	void (*connect_port)(LV2_Handle instance,
+	                     uint32_t   port,
+	                     void *     data_location);
 
 	/** Function pointer that initialises a plugin instance and activates
 	 * it for use.
@@ -257,7 +254,7 @@ typedef struct _LV2_Descriptor {
 	 *
 	 * Note that connect_port() may be called before or after a call to
 	 * activate(). */
-	void (*activate)(LV2_Handle Instance);
+	void (*activate)(LV2_Handle instance);
 
 	/** Function pointer that runs a plugin instance for a block.
 	 *
@@ -273,8 +270,8 @@ typedef struct _LV2_Descriptor {
 	 * If the plugin has the property lv2:hardRTCapable then there are 
 	 * various things that the plugin MUST NOT do within the run()
 	 * function (see lv2.ttl). */
-	void (*run)(LV2_Handle Instance,
-	            uint32_t   SampleCount);
+	void (*run)(LV2_Handle instance,
+	            uint32_t   sampleCount);
 
 	/** This is the counterpart to activate() (see above). If there is
 	 * nothing for deactivate() to do then the plugin writer may provide
@@ -291,7 +288,7 @@ typedef struct _LV2_Descriptor {
 	 * instance will be reinitialised when activate() is called to reuse it.
 	 * Hosts MUST NOT call deactivate() unless activate() was previously
 	 * called. */
-	void (*deactivate)(LV2_Handle Instance);
+	void (*deactivate)(LV2_Handle instance);
 
 	/** This is the counterpart to instantiate() (see above).  Once an instance
 	 * of a plugin has been finished with it can be deleted using this
@@ -302,7 +299,7 @@ typedef struct _LV2_Descriptor {
 	 * call to deactivate() MUST be made before cleanup() is called.
 	 * Hosts MUST NOT call cleanup() unless instantiate() was previously
 	 * called. */
-	void (*cleanup)(LV2_Handle Instance);
+	void (*cleanup)(LV2_Handle instance);
 
 	/** Function pointer that can be used to return additional instance data for
 	 * a plugin defined by some extenion (e.g. a struct containing additional
@@ -319,15 +316,16 @@ typedef struct _LV2_Descriptor {
 	 * NULL if it does not support the extension, but hosts SHOULD NOT use this
 	 * as a discovery method (e.g. hosts should only call this function for
 	 * extensions known to be supported by the plugin from the data file).
+	 *
+	 * The host is never responsible for freeing the returned value.
 	 * 
 	 * NOTE: It is highly recommended that this function returns a struct, and
 	 * NOT a direct function pointer.  Standard C++ (for real reasons) does not
 	 * allow type casts from void* to a function pointer type.  To provide
 	 * additional functions a struct should be returned containing the extra
 	 * function pointers (which is valid standard C++, and a much better idea
-	 * for extensibility anyway).
-	 */
-	void* (*extension_data)(const char * URI); 
+	 * for extensibility anyway). */
+	void* (*extension_data)(const char * uri); 
 
 } LV2_Descriptor;
 
@@ -360,12 +358,12 @@ typedef struct _LV2_Descriptor {
  * index that results in NULL being returned.  Index has no meaning,
  * hosts MUST NOT depend on it remaining constant (ie when serialising)
  * in any way. */
-const LV2_Descriptor * lv2_descriptor(uint32_t Index);
+const LV2_Descriptor * lv2_descriptor(uint32_t index);
 
 
 /** Datatype corresponding to the lv2_descriptor() function. */
 typedef const LV2_Descriptor * 
-(*LV2_Descriptor_Function)(uint32_t Index);
+(*LV2_Descriptor_Function)(uint32_t index);
 
 
 /* ******************************************************************** */
diff --git a/slv2/lv2_gui.h b/slv2/lv2_gui.h
new file mode 100644
index 0000000..696f20b
--- /dev/null
+++ b/slv2/lv2_gui.h
@@ -0,0 +1,346 @@
+/************************************************************************
+ *
+ * In-process UI extension for LV2
+ *
+ * Copyright (C) 2006-2007 Lars Luthman <lars.luthman@gmail.com>
+ * 
+ * Based on lv2.h, which is:
+ *
+ * Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis, 
+ *                         Stefan Westerfeld
+ * Copyright (C) 2006 Steve Harris, Dave Robillard.
+ *
+ * This header 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 header 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 library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
+ * USA.
+ *
+ ***********************************************************************/
+
+/** @file
+    This extension defines an interface that can be used in LV2 plugins and
+    hosts to create GUIs for plugins. The GUIs are plugins that reside in
+    shared object files in an LV2 bundle and be referenced in the RDF file
+    using the triples (Turtle shown)
+<pre>    
+    @prefix guiext: <http://ll-plugins.nongnu.org/lv2/ext/ipgui/1#> .
+    <http://my.plugin>    guiext:gui    <http://my.plugingui> .
+    <http://my.plugingui> guiext:binary <mygui.so> .
+</pre>
+    where <http://my.plugin> is the URI of the plugin, <http://my.plugingui> is
+    the URI of the plugin GUI and <mygui.so> is the relative URI to the shared 
+    object file. While it is possible to have the plugin GUI and the plugin in 
+    the same shared object file it is probably a good idea to keep them 
+    separate so that hosts that don't want GUIs don't have to load the GUI code.
+    
+    (Note: the prefix above is used throughout this file for the same URI)
+    
+    It's entirely possible to have multiple GUIs for the same plugin, or to have
+    the GUI for a plugin in a different bundle from the actual plugin - this
+    way people other than the plugin author can write plugin GUIs independently
+    without editing the original plugin bundle. If a GUI is in a separate bundle
+    the first triple above should be in that bundle's manifest.ttl file so that
+    hosts can find the GUI when scanning the manifests.
+    
+    Note that the process that loads the shared object file containing the GUI
+    code and the process that loads the shared object file containing the 
+    actual plugin implementation does not have to be the same. There are many
+    valid reasons for having the plugin and the GUI in different processes, or
+    even on different machines. This means that you can _not_ use singletons
+    and global variables and expect them to refer to the same objects in the
+    GUI and the actual plugin. The function callback interface defined in this
+    header is all you can expect to work.
+    
+    Since the LV2 specification itself allows for extensions that may add 
+    new types of data and configuration parameters that plugin authors may 
+    want to control with a GUI, this extension allows for meta-extensions that
+    can extend the interface between the GUI and the host. See the
+    instantiate() and extension_data() callback pointers for more details.
+    
+    Note that this extension is NOT a Host Feature. There is no way for a plugin
+    to know whether the host that loads it supports GUIs or not, and the plugin
+    must ALWAYS work without the GUI (although it may be rather useless unless
+    it has been configured using the GUI in a previous session).
+    
+    GUIs written to this specification do not need to be threadsafe - the 
+    functions defined below may only be called in the same thread as the UI
+    main loop is running in.
+*/
+
+#ifndef LV2_GUI_H
+#define LV2_GUI_H
+
+#include "lv2.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/** A pointer to some widget.
+ * The actual type of the widget is defined by the type URI of the GUI.
+ * e.g. if "<http://example.org/somegui> a guiext:GtkGUI", this is a pointer
+ * to a GtkWidget.  All the functionality provided by this extension is
+ * toolkit independent, the host only needs to pass the necessary callbacks
+ * and display the widget, if possible.  Plugins may have several GUIs,
+ * in various toolkits.
+ */
+typedef void* LV2UI_Widget;
+
+  
+/** This handle indicates a particular instance of a GUI.
+    It is valid to compare this to NULL (0 for C++) but otherwise the 
+    host MUST not attempt to interpret it. The GUI plugin may use it to 
+    reference internal instance data. */
+typedef void* LV2UI_Handle;
+
+
+/** This handle indicates a particular plugin instance, provided by the host.
+    It is valid to compare this to NULL (0 for C++) but otherwise the 
+    GUI plugin MUST not attempt to interpret it. The host may use it to 
+    reference internal instance data. */
+typedef void* LV2UI_Controller;
+
+
+/** This is the type of the host-provided function that the GUI can use to
+    send data to a plugin's input ports. The @c buffer parameter must point
+    to a block of data, @c buffer_size bytes large. The contents of this buffer
+    will depend on the class of the port it's being sent to. For ports of the
+    class lv2:ControlPort, buffer_size should be sizeof(float) and the buffer 
+    contents should be a float value. For ports of the class llext:MidiPort the
+    buffer should contain the data bytes of a single MIDI event, and buffer_size
+    should be the number of bytes in the event. No other port classes are
+    allowed, unless the format and the meaning of the buffer passed to this 
+    function is defined in the extension that specifies that class or in a 
+    separate GUI host feature extension that is required by this GUI.
+    
+    The GUI is responsible for allocating the buffer and deallocating it after
+    the call. There are no timing guarantees at all for this function, although
+    the faster the host can get the data to the plugin port the better. A 
+    function pointer of this type will be provided to the GUI by the host in
+    the instantiate() function. */
+typedef void (*LV2UI_Write_Function)(LV2UI_Controller controller,
+                                     uint32_t         port_index,
+                                     uint32_t         buffer_size,
+                                     const void*      buffer);
+
+/** This is the type of the host-provided function that the GUI can use to
+    send arbitrary commands to the plugin. The parameters after the first one
+    should be const char* variables, terminated by a NULL pointer, and will be
+    interpreted as a command with arguments. A function of this type will be 
+    provided to the GUI by the host in the instantiate() function. */
+typedef void (*LV2UI_Command_Function)(LV2UI_Controller   controller,
+                                       uint32_t           argc,
+                                       const char* const* argv);
+
+/** This is the type of the host-provided function that the GUI can use to
+    request a program change in the host. A function of this type will be 
+    provided to the GUI by the host in the instantiate() function. Calling
+    this function does not guarantee that the program will change, it is just
+    a request. If the program does change, the GUI's current_program_changed() 
+    callback will be called, either before or after this function returns
+    depending on whether the GUI host <-> plugin instance communication is
+    synchronous or asynchronous. */
+typedef void (*LV2UI_Program_Change_Function)(LV2UI_Controller controller,
+                                              unsigned char    program);
+
+/** This is the type of the host-provided function that the GUI can use to
+    request that the current state of the plugin is saved to a program.
+    A function of this type will be provided to the GUI by the host in the
+    instantiate function. Calling this function does not guarantee that the
+    state will be saved, it is just a request. If the state is saved, the 
+    GUI's program_added() callback will be called, either before or after
+    this function returns depending on whether the GUI host <-> plugin
+    instance communication is synchronous or asynchronous. */
+typedef void (*LV2UI_Program_Save_Function)(LV2UI_Controller controller,
+                                            unsigned char    program,
+                                            const char*      name);
+
+
+/** */
+typedef struct _LV2UI_Descriptor {
+  
+  /** The URI for this GUI (not for the plugin it controls). */
+  const char* URI;
+  
+  /** Create a new GUI object and return a handle to it. This function works
+      similarly to the instantiate() member in LV2_Descriptor, with the 
+      additions that the URI for the plugin that this GUI is for is passed
+      as a parameter, a function pointer and a controller handle are passed to
+      allow the plugin to write to input ports in the plugin (write_function 
+      and controller) and a pointer to a LV2_Widget is passed, which the GUI
+	  plugin should set to point to a newly created widget which will be the
+	  GUI for the plugin.  This widget may only be destroyed by cleanup().
+      
+      The features array works like the one in the instantiate() member
+      in LV2_Descriptor, except that the URIs should be denoted with the triples
+      <pre>
+      <http://my.plugingui> guiext:optionalFeature <http://my.guifeature>
+      </pre>
+      or 
+      <pre>
+      <http://my.plugingui> guiext:requiredFeature <http://my.guifeature>
+      </pre>
+      in the RDF file, instead of the lv2:optionalFeature or lv2:requiredFeature
+      that is used by host features. These features are associated with the GUI,
+      not with the plugin - they are not actually LV2 Host Features, they just
+      use the same data structure.
+      
+      The same rules apply for these features as for normal host features -
+      if a feature is listed as required in the RDF file and the host does not
+      support it, it must not load the GUI.
+  */
+  LV2UI_Handle (*instantiate)(const struct _LV2UI_Descriptor* descriptor,
+                              const char*                     plugin_uri,
+                              const char*                     bundle_path,
+                              LV2UI_Write_Function            write_function,
+                              LV2UI_Command_Function          command_function,
+                              LV2UI_Program_Change_Function   program_function,
+                              LV2UI_Program_Save_Function     save_function,
+                              LV2UI_Controller                controller,
+                              LV2UI_Widget*                   widget,
+                              const LV2_Host_Feature* const*  host_features);
+
+  
+  /** Destroy the GUI object and the associated widget. 
+   */
+  void (*cleanup)(LV2UI_Handle gui);
+  
+  /** Tell the GUI that something interesting has happened at a plugin port.
+      For control ports this would be when the value in the buffer has changed,
+      for message-based port classes like MIDI or OSC it would be when a 
+      message has arrived in the buffer. For other port classes it is not 
+      defined when this function is called, unless it is specified in the 
+      definition of that port class extension. For control ports the default
+      setting is to call this function whenever an input control port value 
+      has changed but not when any output control port value has changed, for 
+      all other port classes the default setting is to never call this function.
+
+      However, the default setting can be modified by using the following
+      URIs:
+      <pre>
+      guiext:portNotification
+      guiext:noPortNotification
+      guiext:plugin
+      guiext:portIndex
+      </pre>
+      For example, if you want the GUI with uri 
+      <code><http://my.plugingui></code> for the plugin with URI 
+      <code><http://my.plugin></code> to get notified when the value of the 
+      output control port with index 4 changes, you would use the following 
+      in the RDF for your GUI:
+      <pre>
+      <http://my.plugingui> guiext:portNotification [ guiext:plugin <http://my.plugin> ;
+                                                      guiext:portIndex 4 ] .
+      </pre>
+      and similarly with <code>guiext:noPortNotification</code> if you wanted to 
+      prevent notifications for a port for which it would be on by default 
+      otherwise.
+      
+      The @c buffer is only valid during the time of this function call, so if 
+      the GUI wants to keep it for later use it has to copy the contents to an
+      internal buffer.
+      
+      The buffer is subject to the same rules as the ones for the 
+      LV2_Write_Function type. This means that a plugin GUI may not request a
+      portNotification for a port that has a class other than lv2:ControlPort
+      or llext:MidiPort unless the buffer format and meaning is specified in
+      the extension that defines that port class, or in a separate GUI host 
+      feature extension that is required by the GUI. Any GUI that does that
+      should be considered broken and the host should not use it.
+      
+      This member may be set to NULL if the GUI is not interested in any 
+      port events.
+  */
+  void (*port_event)(LV2UI_Handle   gui,
+                     uint32_t       port,
+                     uint32_t       buffer_size,
+                     const void*    buffer);
+  
+  /** This function is called when the plugin instance wants to send feedback
+      to the GUI. It may be called in response to a command function call,
+      either before or after the command function has returned (depending on
+      whether the GUI host <-> plugin instance communication is synchronous or
+      asynchronous). */
+  void (*feedback)(LV2UI_Handle       gui, 
+                   uint32_t           argc, 
+                   const char* const* argv);
+  
+  /** This function is called when the host adds a new program to its program
+      list, or changes the name of an old one. It may be set to NULL if the 
+      GUI isn't interested in displaying program information. */
+  void (*program_added)(LV2UI_Handle  gui, 
+                        unsigned char number, 
+                        const char*   name);
+  
+  /** This function is called when the host removes a program from its program
+      list. It may be set to NULL if the GUI isn't interested in displaying
+      program information. */
+  void (*program_removed)(LV2UI_Handle  gui, 
+                          unsigned char number);
+  
+  /** This function is called when the host clears its program list. It may be
+      set to NULL if the GUI isn't interested in displaying program 
+      information. */
+  void (*programs_cleared)(LV2UI_Handle gui);
+  
+  /** This function is called when the host changes the current program. It may
+      be set to NULL if the GUI isn't interested in displaying program 
+      information. */
+  void (*current_program_changed)(LV2UI_Handle  gui, 
+                                  unsigned char number);
+
+  /** Returns a data structure associated with an extension URI, for example
+      a struct containing additional function pointers. Avoid returning
+      function pointers directly since standard C++ has no valid way of
+      casting a void* to a function pointer. This member may be set to NULL
+      if the GUI is not interested in supporting any extensions. This is similar
+      to the extension_data() member in LV2_Descriptor.
+  */
+  void* (*extension_data)(LV2UI_Handle gui,
+                          const char*  uri);
+
+} LV2UI_Descriptor;
+
+
+
+/** A plugin programmer must include a function called "lv2ui_descriptor"
+    with the following function prototype within the shared object
+    file. This function will have C-style linkage (if you are using
+    C++ this is taken care of by the 'extern "C"' clause at the top of
+    the file). This function will be accessed by the GUI host using the 
+    @c dlsym() function and called to get a LV2UI_UIDescriptor for the
+    wanted plugin.
+    
+    Just like lv2_descriptor(), this function takes an index parameter. The
+    index should only be used for enumeration and not as any sort of ID number -
+    the host should just iterate from 0 and upwards until the function returns
+    NULL, or a descriptor with an URI matching the one the host is looking for
+    is returned.
+*/
+const LV2UI_Descriptor* lv2ui_descriptor(uint32_t index);
+
+
+/** This is the type of the lv2ui_descriptor() function. */
+typedef const LV2UI_Descriptor* (*LV2UI_DescriptorFunction)(uint32_t index);
+
+
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif /* LV2_GUI_H */
+
diff --git a/slv2/pluginguiinstance.h b/slv2/pluginguiinstance.h
index 7801256..2eb9c60 100644
--- a/slv2/pluginguiinstance.h
+++ b/slv2/pluginguiinstance.h
@@ -25,7 +25,7 @@ extern "C" {
 #endif
 
 #include <assert.h>
-#include <slv2/lv2-gtk2gui.h>
+#include <slv2/lv2_gui.h>
 #include <slv2/plugin.h>
 
 /** \defgroup lib Plugin GUI library access
@@ -72,11 +72,14 @@ typedef struct _SLV2GUIInstance {
  * \return NULL if instantiation failed.
  */
 SLV2GUIInstance
-slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                 plugin,
-                                 SLV2Value                  gui,
-                                 LV2UI_Set_Control_Function control_function,
-                                 LV2UI_Controller           controller,
-                                 const LV2_Host_Feature**   host_features);
+slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                     plugin,
+                                 SLV2Value                      gui,
+                                 LV2UI_Write_Function           write_function,
+                                 LV2UI_Command_Function         command_function,
+                                 LV2UI_Program_Change_Function  program_function,
+                                 LV2UI_Program_Save_Function    save_function,
+                                 LV2UI_Controller               controller,
+                                 const LV2_Host_Feature* const* host_features);
 
 
 /** Free a plugin GUI instance.
@@ -87,9 +90,9 @@ void
 slv2_gtk2_gui_instance_free(SLV2GUIInstance instance);
 
 
-/** Get the GTK+ 2.0 widget for the GUI instance.
+/** Get the widget for the GUI instance.
  */
-struct _GtkWidget*
+LV2UI_Widget
 slv2_gtk2_gui_instance_get_widget(SLV2GUIInstance instance);
 
 
diff --git a/src/pluginguiinstance.c b/src/pluginguiinstance.c
index c115751..a29e64d 100644
--- a/src/pluginguiinstance.c
+++ b/src/pluginguiinstance.c
@@ -32,11 +32,14 @@
 
 
 SLV2GUIInstance
-slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                 plugin,
-                                 SLV2Value                  gui,
-                                 LV2UI_Set_Control_Function control_function,
-                                 LV2UI_Controller           controller,
-                                 const LV2_Host_Feature**   host_features)
+slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                     plugin,
+                                 SLV2Value                      gui,
+                                 LV2UI_Write_Function           write_function,
+                                 LV2UI_Command_Function         command_function,
+                                 LV2UI_Program_Change_Function  program_function,
+                                 LV2UI_Program_Save_Function    save_function,
+                                 LV2UI_Controller               controller,
+                                 const LV2_Host_Feature* const* host_features)
 {
 	assert(gui->type == SLV2_VALUE_GUI);
 
@@ -48,7 +51,7 @@ slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                 plugin,
 	bool local_host_features = (host_features == NULL);
 	if (local_host_features) {
 		host_features = malloc(sizeof(LV2_Host_Feature));
-		host_features[0] = NULL;
+		((LV2_Host_Feature**)host_features)[0] = NULL;
 	}
 	
 	const char* const lib_uri = slv2_value_as_uri(slv2_plugin_get_gui_library_uri(plugin, gui));
@@ -101,9 +104,12 @@ slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                 plugin,
 				impl->lv2ui_handle = ld->instantiate(ld, 
 						slv2_plugin_get_uri(plugin),
 						(char*)bundle_path, 
-						control_function,
+						write_function,
+						command_function,
+						program_function,
+						save_function,
 						controller,
-						(struct _GtkWidget**)&impl->widget,
+						&impl->widget,
 						host_features);
 				impl->lib_handle = lib;
 				result->pimpl = impl;
@@ -130,7 +136,7 @@ slv2_plugin_gtk2_gui_instantiate(SLV2Plugin                 plugin,
 	}
 
 	if (local_host_features)
-		free(host_features);
+		free((LV2_Host_Feature**)host_features);
 
 	return result;
 }
@@ -150,7 +156,7 @@ slv2_gtk2_gui_instance_free(SLV2GUIInstance instance)
 }
 
 
-struct _GtkWidget*
+LV2UI_Widget
 slv2_gtk2_gui_instance_get_widget(SLV2GUIInstance instance) {
 	return instance->pimpl->widget;
 }
diff --git a/src/slv2_internal.h b/src/slv2_internal.h
index d2296cf..1dedc50 100644
--- a/src/slv2_internal.h
+++ b/src/slv2_internal.h
@@ -28,7 +28,7 @@ extern "C" {
 #include <inttypes.h>
 #include <librdf.h>
 #include <slv2/types.h>
-#include <slv2/lv2-gtk2gui.h>
+#include <slv2/lv2_gui.h>
 
 
 
@@ -103,7 +103,7 @@ struct _SLV2GUIInstanceImpl {
 	void*                   lib_handle;
 	const LV2UI_Descriptor* lv2ui_descriptor;
 	LV2UI_Handle            lv2ui_handle;
-	void*                   widget;
+	LV2UI_Widget            widget;
 };