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+/*
+ LV2 UI Extension
+ Copyright 2009-2011 David Robillard <d@drobilla.net>
+ Copyright 2006-2008 Lars Luthman <lars.luthman@gmail.com>
+
+ 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.
+*/
+
+/**
+ * @file
+ * C header for the LV2 UI extension <http://lv2plug.in/ns/extensions/ui>.
+ */
+
+#ifndef LV2_UI_H
+#define LV2_UI_H
+
+#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
+
+#define LV2_UI_URI "http://lv2plug.in/ns/extensions/ui"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ A pointer to some widget or other type of UI handle.
+
+ The actual type is defined by the type URI of the UI. 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 UIs, in various toolkits.
+*/
+typedef void* LV2UI_Widget;
+
+/**
+ A pointer to a particular instance of a UI.
+
+ It is valid to compare this to NULL (0 for C++) but otherwise the host MUST
+ not attempt to interpret it. The UI plugin may use it to reference internal
+ instance data.
+*/
+typedef void* LV2UI_Handle;
+
+/**
+ A pointer to a particular plugin controller, provided by the host.
+
+ It is valid to compare this to NULL (0 for C++) but otherwise the UI plugin
+ MUST NOT attempt to interpret it. The host may use it to reference internal
+ instance data.
+*/
+typedef void* LV2UI_Controller;
+
+/**
+ The type of the host-provided function that the UI 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 and what the host should do with it
+ depends on the value of the @c format parameter.
+
+ The @c format parameter should either be 0 or a numeric ID for a "Transfer
+ mechanism". Transfer mechanisms are Features and may be defined in
+ meta-extensions. They specify how to translate the data buffers passed to
+ this function to input data for the plugin ports. If a UI wishes to write
+ data to an input port, it must list a transfer mechanism Feature for that
+ port's class as an optional or required feature (depending on whether the UI
+ will work without being able to write to that port or not). The only
+ exception is when the UI wants to write single float values to input ports
+ of the class lv2:ControlPort, in which case @c buffer_size should always be
+ 4, the buffer should always contain a single IEEE-754 float, and @c format
+ should be 0.
+
+ The numeric IDs for the transfer mechanisms are provided by a URI-to-integer
+ mapping function provided by the host, using the URI Map feature
+ <http://lv2plug.in/ns/ext/uri-map> with the map URI
+ "http://lv2plug.in/ns/extensions/ui". Thus a UI that requires transfer
+ mechanism features also requires the URI Map feature, but this is implicit -
+ the UI does not have to list the URI map feature as a required or optional
+ feature in it's RDF data.
+
+ An UI MUST NOT pass a @c format parameter value (except 0) that has not been
+ returned by the host-provided URI mapping function for a host-supported
+ transfer mechanism feature URI.
+
+ The UI MUST NOT try to write to a port for which there is no specified
+ transfer mechanism, or to an output port. The UI is responsible for
+ allocating the buffer and deallocating it after the call.
+*/
+typedef void (*LV2UI_Write_Function)(LV2UI_Controller controller,
+ uint32_t port_index,
+ uint32_t buffer_size,
+ uint32_t format,
+ const void* buffer);
+
+/**
+ The implementation of a UI.
+
+ A pointer to an object of this type is returned by the lv2ui_descriptor()
+ function.
+*/
+typedef struct _LV2UI_Descriptor {
+ /**
+ The URI for this UI (not for the plugin it controls).
+ */
+ const char* URI;
+
+ /**
+ Create a new UI object and return a handle to it. This function works
+ similarly to the instantiate() member in LV2_Descriptor.
+
+ @param descriptor The descriptor for the UI that you want to instantiate.
+
+ @param plugin_uri The URI of the plugin that this UI will control.
+
+ @param bundle_path The path to the bundle containing the RDF data file
+ that references this shared object file, including the trailing '/'.
+
+ @param write_function A function provided by the host that the UI can use
+ to send data to the plugin's input ports.
+
+ @param controller A handle for the plugin instance that should be passed
+ as the first parameter of @c write_function.
+
+ @param widget A pointer to an LV2UI_Widget. The UI will write a widget
+ pointer to this location (what type of widget depends on the RDF class of
+ the UI) that will be the main UI widget.
+
+ @param features An array of LV2_Feature pointers. The host must pass all
+ feature URIs that it and the UI supports and any additional data, just
+ like in the LV2 plugin instantiate() function. Note that UI features and
+ plugin features are NOT necessarily the same, they just share the same
+ data structure - this will probably not be the same array as the one the
+ plugin host passes to a plugin.
+
+ */
+ LV2UI_Handle (*instantiate)(const struct _LV2UI_Descriptor* descriptor,
+ const char* plugin_uri,
+ const char* bundle_path,
+ LV2UI_Write_Function write_function,
+ LV2UI_Controller controller,
+ LV2UI_Widget* widget,
+ const LV2_Feature* const* features);
+
+
+ /**
+ Destroy the UI object and the associated widget. The host must not try
+ to access the widget after calling this function.
+ */
+ void (*cleanup)(LV2UI_Handle ui);
+
+ /**
+ Tell the UI that something interesting has happened at a plugin port.
+
+ What is interesting and how it is written to the buffer passed to this
+ function is defined by the @c format parameter, which has the same meaning
+ as in LV2UI_Write_Function. The only exception is ports of the class
+ lv2:ControlPort, for which this function should be called when the port
+ value changes (it does not have to be called for every single change if
+ the host's UI thread has problems keeping up with the thread the plugin is
+ running in), @c buffer_size should be 4, the buffer should contain a
+ single IEEE-754 float, and @c format should be 0.
+
+ By default, the host should only call this function for input ports of the
+ lv2:ControlPort class. However, the default setting can be modified by
+ using the following URIs in the UI's RDF data:
+ <pre>
+ uiext:portNotification
+ uiext:noPortNotification
+ uiext:plugin
+ uiext:portIndex
+ </pre>
+ For example, if you want the UI with uri
+ <code><http://my.pluginui></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 UI:
+ <pre>
+ <http://my.pluginui> uiext:portNotification [ uiext:plugin <http://my.plugin> ;
+ uiext:portIndex 4 ] .
+ </pre>
+ and similarly with <code>uiext:noPortNotification</code> if you wanted
+ to prevent notifications for a port for which it would be on by default
+ otherwise. The UI is not allowed to request notifications for ports of
+ types for which no transfer mechanism is specified, if it does it should
+ be considered broken and the host should not load it.
+
+ The @c buffer is only valid during the time of this function call, so if
+ the UI wants to keep it for later use it has to copy the contents to an
+ internal buffer.
+
+ This member may be set to NULL if the UI is not interested in any
+ port events.
+ */
+ void (*port_event)(LV2UI_Handle ui,
+ uint32_t port_index,
+ uint32_t buffer_size,
+ uint32_t format,
+ const void* buffer);
+
+ /**
+ Return a data structure associated with an extension URI, for example
+ a struct containing additional function pointers.
+
+ Avoid returning function pointers directly since standard C/C++ has no
+ valid way of casting a void* to a function pointer. This member may be set
+ to NULL if the UI is not interested in supporting any extensions. This is
+ similar to the extension_data() member in LV2_Descriptor.
+ */
+ const void* (*extension_data)(const char* uri);
+
+} LV2UI_Descriptor;
+
+/**
+ A plugin UI 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 UI 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.
+*/
+const LV2UI_Descriptor* lv2ui_descriptor(uint32_t index);
+
+/**
+ The type of the lv2ui_descriptor() function.
+*/
+typedef const LV2UI_Descriptor* (*LV2UI_DescriptorFunction)(uint32_t index);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* LV2_UI_H */