242 lines
11 KiB
C
242 lines
11 KiB
C
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/* LV2 UI Extension
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* Copyright (C) 2006-2008 Lars Luthman <lars.luthman@gmail.com>
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* Copyright (C) 2009-2010 David Robillard <d@drobilla.net>
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*
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* Based on lv2.h, which was
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* Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis,
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* Stefan Westerfeld
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* Copyright (C) 2006 Steve Harris, David Robillard.
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*
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* This header is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License,
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* or (at your option) any later version.
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*
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* This header is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
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* USA.
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*
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*/
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/** @file
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* C header for the LV2 UI extension <http://lv2plug.in/ns/extensions/ui>.
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*/
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#ifndef LV2_UI_H
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#define LV2_UI_H
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#include "lv2.h"
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#define LV2_UI_URI "http://lv2plug.in/ns/extensions/ui"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** A pointer to some widget or other type of UI handle.
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The actual type is defined by the type URI of the UI.
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All the functionality provided by this extension is toolkit
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independent, the host only needs to pass the necessary callbacks and
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display the widget, if possible. Plugins may have several UIs, in various
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toolkits. */
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typedef void* LV2UI_Widget;
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/** A pointer to a particular instance of a UI.
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It is valid to compare this to NULL (0 for C++) but otherwise the
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host MUST not attempt to interpret it. The UI plugin may use it to
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reference internal instance data. */
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typedef void* LV2UI_Handle;
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/** A pointer to a particular plugin controller, provided by the host.
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It is valid to compare this to NULL (0 for C++) but otherwise the
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UI plugin MUST not attempt to interpret it. The host may use it to
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reference internal instance data. */
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typedef void* LV2UI_Controller;
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/** The type of the host-provided function that the UI can use to
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send data to a plugin's input ports. The @c buffer parameter must point
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to a block of data, @c buffer_size bytes large. The contents of this buffer
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and what the host should do with it depends on the value of the @c format
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parameter.
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The @c format parameter should either be 0 or a numeric ID for a "Transfer
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mechanism". Transfer mechanisms are Features and may be defined in
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meta-extensions. They specify how to translate the data buffers passed
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to this function to input data for the plugin ports. If a UI wishes to
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write data to an input port, it must list a transfer mechanism Feature
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for that port's class as an optional or required feature (depending on
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whether the UI will work without being able to write to that port or not).
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The only exception is when the UI wants to write single float values to
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input ports of the class lv2:ControlPort, in which case @c buffer_size
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should always be 4, the buffer should always contain a single IEEE-754
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float, and @c format should be 0.
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The numeric IDs for the transfer mechanisms are provided by a
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URI-to-integer mapping function provided by the host, using the URI Map
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feature <http://lv2plug.in/ns/ext/uri-map> with the map URI
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"http://lv2plug.in/ns/extensions/ui". Thus a UI that requires transfer
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mechanism features also requires the URI Map feature, but this is
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implicit - the UI does not have to list the URI map feature as a required
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or optional feature in it's RDF data.
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An UI MUST NOT pass a @c format parameter value (except 0) that has not
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been returned by the host-provided URI mapping function for a
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host-supported transfer mechanism feature URI.
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The UI MUST NOT try to write to a port for which there is no specified
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transfer mechanism, or to an output port. The UI is responsible for
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allocating the buffer and deallocating it after the call.
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*/
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typedef void (*LV2UI_Write_Function)(LV2UI_Controller controller,
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uint32_t port_index,
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uint32_t buffer_size,
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uint32_t format,
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const void* buffer);
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/** This struct contains the implementation of a UI. A pointer to an
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object of this type is returned by the lv2ui_descriptor() function.
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*/
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typedef struct _LV2UI_Descriptor {
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/** The URI for this UI (not for the plugin it controls). */
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const char* URI;
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/** Create a new UI object and return a handle to it. This function works
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similarly to the instantiate() member in LV2_Descriptor.
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@param descriptor The descriptor for the UI that you want to instantiate.
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@param plugin_uri The URI of the plugin that this UI will control.
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@param bundle_path The path to the bundle containing the RDF data file
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that references this shared object file, including the
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trailing '/'.
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@param write_function A function provided by the host that the UI can
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use to send data to the plugin's input ports.
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@param controller A handle for the plugin instance that should be passed
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as the first parameter of @c write_function.
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@param widget A pointer to an LV2UI_Widget. The UI will write a
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widget pointer to this location (what type of widget
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depends on the RDF class of the UI) that will be the
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main UI widget.
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@param features An array of LV2_Feature pointers. The host must pass
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all feature URIs that it and the UI supports and any
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additional data, just like in the LV2 plugin
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instantiate() function. Note that UI features and plugin
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features are NOT necessarily the same, they just share
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the same data structure - this will probably not be the
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same array as the one the plugin host passes to a
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plugin.
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*/
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LV2UI_Handle (*instantiate)(const struct _LV2UI_Descriptor* descriptor,
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const char* plugin_uri,
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const char* bundle_path,
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LV2UI_Write_Function write_function,
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LV2UI_Controller controller,
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LV2UI_Widget* widget,
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const LV2_Feature* const* features);
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/** Destroy the UI object and the associated widget. The host must not try
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to access the widget after calling this function.
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*/
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void (*cleanup)(LV2UI_Handle ui);
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/** Tell the UI that something interesting has happened at a plugin port.
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What is interesting and how it is written to the buffer passed to this
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function is defined by the @c format parameter, which has the same
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meaning as in LV2UI_Write_Function. The only exception is ports of the
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class lv2:ControlPort, for which this function should be called
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when the port value changes (it does not have to be called for every
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single change if the host's UI thread has problems keeping up with the
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thread the plugin is running in), @c buffer_size should be 4, the buffer
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should contain a single IEEE-754 float, and @c format should be 0.
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By default, the host should only call this function for input ports of
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the lv2:ControlPort class. However, the default setting can be modified
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by using the following URIs in the UI's RDF data:
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<pre>
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uiext:portNotification
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uiext:noPortNotification
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uiext:plugin
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uiext:portIndex
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</pre>
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For example, if you want the UI with uri
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<code><http://my.pluginui></code> for the plugin with URI
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<code><http://my.plugin></code> to get notified when the value of the
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output control port with index 4 changes, you would use the following
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in the RDF for your UI:
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<pre>
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<http://my.pluginui> uiext:portNotification [ uiext:plugin <http://my.plugin> ;
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uiext:portIndex 4 ] .
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</pre>
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and similarly with <code>uiext:noPortNotification</code> if you wanted
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to prevent notifications for a port for which it would be on by default
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otherwise. The UI is not allowed to request notifications for ports of
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types for which no transfer mechanism is specified, if it does it should
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be considered broken and the host should not load it.
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The @c buffer is only valid during the time of this function call, so if
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the UI wants to keep it for later use it has to copy the contents to an
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internal buffer.
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This member may be set to NULL if the UI is not interested in any
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port events.
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*/
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void (*port_event)(LV2UI_Handle ui,
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uint32_t port_index,
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uint32_t buffer_size,
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uint32_t format,
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const void* buffer);
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/** Returns a data structure associated with an extension URI, for example
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a struct containing additional function pointers. Avoid returning
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function pointers directly since standard C/C++ has no valid way of
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casting a void* to a function pointer. This member may be set to NULL
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if the UI is not interested in supporting any extensions. This is similar
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to the extension_data() member in LV2_Descriptor.
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*/
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const void* (*extension_data)(const char* uri);
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} LV2UI_Descriptor;
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/** A plugin UI programmer must include a function called "lv2ui_descriptor"
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with the following function prototype within the shared object
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file. This function will have C-style linkage (if you are using
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C++ this is taken care of by the 'extern "C"' clause at the top of
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the file). This function will be accessed by the UI host using the
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@c dlsym() function and called to get a LV2UI_UIDescriptor for the
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wanted plugin.
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Just like lv2_descriptor(), this function takes an index parameter. The
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index should only be used for enumeration and not as any sort of ID number -
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the host should just iterate from 0 and upwards until the function returns
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NULL or a descriptor with an URI matching the one the host is looking for.
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*/
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const LV2UI_Descriptor* lv2ui_descriptor(uint32_t index);
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/** This is the type of the lv2ui_descriptor() function. */
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typedef const LV2UI_Descriptor* (*LV2UI_DescriptorFunction)(uint32_t index);
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#ifdef __cplusplus
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}
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#endif
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#endif
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