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Diffstat (limited to 'lv2/lv2_ui.h')
| -rw-r--r-- | lv2/lv2_ui.h | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/lv2/lv2_ui.h b/lv2/lv2_ui.h new file mode 100644 index 0000000..4be2c24 --- /dev/null +++ b/lv2/lv2_ui.h @@ -0,0 +1,372 @@ +/************************************************************************
+ *
+ * In-process UI extension for LV2
+ *
+ * Copyright (C) 2006-2008 Lars Luthman <lars.luthman@gmail.com>
+ *
+ * Based on lv2.h, which was
+ *
+ * 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 UIs for plugins. The UIs are plugins that reside in
+ shared object files in an LV2 bundle and are referenced in the RDF data
+ using the triples (Turtle shown)
+<pre>
+ @@prefix uiext: <http://lv2plug.in/ns/extensions/ui#> .
+ <http://my.plugin> uiext:ui <http://my.pluginui> .
+ <http://my.plugin> a uiext:GtkUI .
+ <http://my.pluginui> uiext:binary <myui.so> .
+</pre>
+ where <http://my.plugin> is the URI of the plugin, <http://my.pluginui> is
+ the URI of the plugin UI and <myui.so> is the relative URI to the shared
+ object file. While it is possible to have the plugin UI 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 UIs don't have to load the UI code.
+ A UI MUST specify its class in the RDF data, in this case uiext:GtkUI. The
+ class defines what type the UI is, e.g. what graphics toolkit it uses.
+ There are no UI classes defined in this extension, those are specified
+ separately (and anyone can define their own).
+
+ (Note: the prefix above is used throughout this file for the same URI)
+
+ It's entirely possible to have multiple UIs for the same plugin, or to have
+ the UI for a plugin in a different bundle from the actual plugin - this
+ way people other than the plugin author can write plugin UIs independently
+ without editing the original plugin bundle.
+
+ Note that the process that loads the shared object file containing the UI
+ 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 UI 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
+ UI 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 UI, this extension allows for meta-extensions that
+ can extend the interface between the UI and the host. These extensions
+ mirror the extensions used for plugins - there are required and optional
+ "features" that you declare in the RDF data for the UI as
+<pre>
+ <http://my.pluginui> uiext:requiredFeature <http://my.feature> .
+ <http://my.pluginui> uiext:optionalFeature <http://my.feature> .
+</pre>
+ These predicates have the same semantics as lv2:requiredFeature and
+ lv2:optionalFeature - if a UI is declaring a feature as required, the
+ host is NOT allowed to load it unless it supports that feature, and if it
+ does support a feature (required or optional) it MUST pass that feature's
+ URI and any additional data (specified by the meta-extension that defines
+ the feature) in a LV2_Feature struct (as defined in lv2.h) to the UI's
+ instantiate() function.
+
+ These features may be used to specify how to pass data between the UI
+ and the plugin port buffers - see LV2UI_Write_Function for details.
+
+ There are four features defined in this extension that hosts may want to
+ implement:
+
+<pre>
+ uiext:makeResident
+</pre>
+ If this feature is required by a UI the host MUST NEVER unload the shared
+ library containing the UI implementation during the lifetime of the host
+ process (e.g. never calling dlclose() on Linux). This feature may be
+ needed by e.g. a Gtk UI that registers its own Glib types using
+ g_type_register_static() - if it gets unloaded and then loaded again the
+ type registration will break, since there is no way to unregister the
+ types when the library is unloaded. The data pointer in the LV2_Feature
+ for this feature should always be set to NULL.
+
+<pre>
+ uiext:makeSONameResident
+</pre>
+ This feature is ELF specific - it should only be used by UIs that
+ use the ELF file format for the UI shared object files (e.g. on Linux).
+ If it is required by an UI the UI should also list a number of SO names
+ (shared object names) for libraries that the UI shared object
+ depends on and that may not be unloaded during the lifetime of the host
+ process, using the predicate @c uiext:residentSONames, like this:
+<pre>
+ <http://my.pluginui> uiext:residentSONames "libgtkmm-2.4.so.1", "libfoo.so.0"
+</pre>
+ The host MUST then make sure that the shared libraries with the given ELF
+ SO names are not unloaded when the plugin UI is, but stay loaded during
+ the entire lifetime of the host process. On Linux this can be accomplished
+ by calling dlopen() on the shared library file with that SO name and never
+ calling a matching dlclose(). However, if a plugin UI requires the
+ @c uiext:makeSONameResident feature, it MUST ALWAYS be safe for the host to
+ just never unload the shared object containing the UI implementation, i.e.
+ act as if the UI required the @c uiext:makeResident feature instead. Thus
+ the host only needs to find the shared library files corresponding to the
+ given SO names if it wants to save RAM by unloading the UI shared object
+ file when it is no longer needed. The data pointer for the LV2_Feature for
+ this feature should always be set to NULL.
+
+<pre>
+ uiext:noUserResize
+</pre>
+ If an UI requires this feature it indicates that it does not make sense
+ to let the user resize the main widget, and the host should prevent that.
+ This feature may not make sense for all UI types. The data pointer for the
+ LV2_Feature for this feature should always be set to NULL.
+
+<pre>
+ uiext:fixedSize
+</pre>
+ If an UI requires this feature it indicates the same thing as
+ uiext:noUserResize, and additionally it means that the UI will not resize
+ the main widget on its own - it will always remain the same size (e.g. a
+ pixmap based GUI). This feature may not make sense for all UI types.
+ The data pointer for the LV2_Feature for this feature should always be set
+ to NULL.
+
+
+ UIs 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.
+
+ Note that this UI extension is NOT a lv2:Feature. There is no way for a
+ plugin to know whether the host that loads it supports UIs or not, and
+ the plugin must ALWAYS work without the UI (although it may be rather
+ useless unless it has been configured using the UI in a previous session).
+
+ A UI does not have to be a graphical widget, it could just as well be a
+ server listening for OSC input or an interface to some sort of hardware
+ device, depending on the RDF class of the UI.
+*/
+
+#ifndef LV2_UI_H
+#define LV2_UI_H
+
+#include <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;
+
+
+/** This handle indicates 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;
+
+
+/** 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
+ UI plugin MUST not attempt to interpret it. The host may use it to
+ reference internal plugin instance data. */
+typedef void* LV2UI_Controller;
+
+
+/** This is 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);
+
+
+/** This struct contains the implementation of an 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 and the
+ buffer should contain a single IEEE-754 float. In this case the @c format
+ parameter 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);
+
+ /** 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 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);
+
+
+/** This is the type of the lv2ui_descriptor() function. */
+typedef const LV2UI_Descriptor* (*LV2UI_DescriptorFunction)(uint32_t index);
+
+
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif
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