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authorDavid Robillard <d@drobilla.net>2011-03-26 20:31:03 +0000
committerDavid Robillard <d@drobilla.net>2011-03-26 20:31:03 +0000
commit1a661a61925b9ff59947be28ad4be95527079ea1 (patch)
tree76f695c2320f19dd90024a9c351256861007af13
parent7a9a84b4cc5a6f2d7fce104de7ff5994cabb4ccb (diff)
downloadlv2-1a661a61925b9ff59947be28ad4be95527079ea1.tar.xz
Clean up documentation.
-rw-r--r--ext/ui.lv2/ui.h420
-rw-r--r--ext/ui.lv2/ui.ttl68
2 files changed, 246 insertions, 242 deletions
diff --git a/ext/ui.lv2/ui.h b/ext/ui.lv2/ui.h
index 82c14c0..599ed0e 100644
--- a/ext/ui.lv2/ui.h
+++ b/ext/ui.lv2/ui.h
@@ -2,7 +2,7 @@
*
* In-process UI extension for LV2
*
- * Copyright (C) 2006-2010 Lars Luthman <mail@larsluthman.net>
+ * Copyright (C) 2006-2011 Lars Luthman <mail@larsluthman.net>
*
* Based on lv2.h, which was
*
@@ -27,23 +27,24 @@
*
***********************************************************************/
-/** @file
- This file specifies a C API for communication between an LV2 host and an
- LV2 UI. The interface is similar to the one used for actual LV2 plugins.
+/**
+ @file ui.h C API for the LV2 UI extension <http://lv2plug.in/ns/ext/ui>.
+
+ This file specifies a C API for communication between an LV2 host and an
+ LV2 UI. The interface is similar to the one used for actual LV2 plugins.
- The entry point is the function lv2ui_descriptor().
+ The entry point is the function lv2ui_descriptor().
*/
#ifndef LV2_UI_H
#define LV2_UI_H
-
#include <lv2.h>
-/** The URI prefix for this extension. */
+/** The URI of this extension (note this is not the same as the prefix). */
#define LV2_UI_URI "http://lv2plug.in/ns/ext/ui"
-/** The numerical index returned by LV2_UI_Host_Descriptor::port_index() for
+/** The numerical ID returned by LV2_UI_Host_Descriptor::port_index() for
invalid port symbols. */
#define LV2_UI_INVALID_PORT_INDEX ((uint32_t)-1)
@@ -58,246 +59,255 @@
extern "C" {
#endif
-
-/** A pointer to a widget or other type of UI handle.
- The actual type is defined by the type of the UI defined in the RDF data.
- 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. */
+/**
+ A pointer to a widget or other type of UI.
+ The actual type is defined by the type of the UI defined in the RDF data.
+ 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* LV2_UI_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. */
+/**
+ Handle for 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 may use it to reference internal
+ instance data.
+*/
typedef void* LV2_UI_Handle;
-
-/** An object of this type is passed to the UI's instantiate() function,
- and the UI must in turn pass it as the first parameter to the callbacks
- in LV2_UI_Host_Descriptor. The host may use it to reference internal data,
- such as the plugin instance that the UI is associated with. The UI
- MUST NOT interpret the value of an LV2_UI_Host_Handle in any way. */
+/**
+ Handle for host functions and data provided to a UI.
+ An object of this type is passed to the UI's instantiate() function, and the
+ UI must in turn pass it as the first parameter to the callbacks in
+ LV2_UI_Host_Descriptor. The host may use it to reference internal data, such
+ as the plugin instance that the UI is associated with. The UI MUST NOT
+ interpret the value of an LV2_UI_Host_Handle in any way.
+*/
typedef void* LV2_UI_Host_Handle;
+/**
+ Host-provided functions that the UI can use to control the plugin instance.
+
+ A pointer to an object of this type is passed to the lv2ui_descriptor()
+ function.
-/** This struct contains pointers to the host-provided functions that the
- UI can use to control the plugin instance. A pointer to an object of this
- type is passed to the lv2ui_descriptor() function.
-
- The host must provide non-NULL values for all the function pointers.
+ The host MUST provide non-NULL values for all the function pointers.
*/
typedef struct _LV2_UI_Host_Descriptor {
- /** This is a 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 port_protocol
- parameter.
+ /**
+ Send data to one of the plugin's input ports.
+
+ The @a buffer parameter MUST point to a block of data @a buffer_size
+ bytes large. The contents of this buffer and what the host should do
+ with it depends on the value of the @a port_protocol parameter.
- The @c port_protocol parameter should be a numeric ID for a
- ui:PortProtocol. Numeric IDs for PortProtocols are retrieved using the
- port_protocol_id() function.
+ The @a port_protocol parameter MUST be a numeric ID for a
+ ui:PortProtocol. Numeric IDs for PortProtocols are retrieved using the
+ port_protocol_id() function.
- The @c buffer is only valid during the time of this function call, so if
- the host wants to keep it for later use it has to copy the contents to an
- internal buffer.
+ The @a buffer is only valid during the time of this function call, so if
+ the host wants to keep it for later use it has to copy the contents to an
+ internal buffer.
- @param host_handle The LV2_UI_Host_Handle that was passed to the UI's
- instantiate() function.
- @param port_index The index of the port that the data should be written
- to, as returned by port_index().
- @param buffer_size The size of the data pointer to by @c buffer, in
- bytes.
- @param port_protocol The numeric ID for the Port Protocol to use,
- as returned by port_protocol_id().
- */
- void (*write_port)(LV2_UI_Host_Handle host_handle,
- uint32_t port_index,
- uint32_t buffer_size,
- uint32_t port_protocol,
- void const* buffer);
+ @param host_handle The @a host_handle that was passed to the UI's
+ instantiate() function.
+ @param port_index The index of the port that the data should be written
+ to, as returned by port_index().
+ @param buffer_size The size of the data pointed to by @a buffer, in
+ bytes.
+ @param port_protocol The numeric ID of the Port Protocol to use,
+ as returned by port_protocol_id().
+ */
+ void (*write_port)(LV2_UI_Host_Handle host_handle,
+ uint32_t port_index,
+ uint32_t buffer_size,
+ uint32_t port_protocol,
+ void const* buffer);
- /** Returns a numerical index for a port. This index is used when writing
- data to ports using write_port() and whe receiving data using
- port_event(). If @c port_symbol is not a valid port symbol for @c plugin
- the host it MUST return LV2_UI_INVALID_PORT_INDEX.
+ /**
+ Return the numerical index for a port.
+ This index is used when writing data to ports using write_port() and whe
+ receiving data using port_event(). If @a port_symbol is not a valid port
+ symbol for @a plugin the host it MUST return
+ LV2_UI_INVALID_PORT_INDEX. For performance reasons it may be a good idea
+ to cache port indices in the UI at instantiation time.
- @param host_handle The LV2_UI_Host_Handle that was passed to the UI's
- instantiate() function.
- @param port_symbol A port symbol, as defined in the RDF data for
- the plugin.
- */
- uint32_t (*port_index)(LV2_UI_Host_Handle host_handle,
- char const* port_symbol);
+ @param host_handle The LV2_UI_Host_Handle that was passed to the UI's
+ instantiate() function.
+ @param port_symbol The port's symbol, as defined in the RDF data for
+ the plugin.
+ */
+ uint32_t (*port_index)(LV2_UI_Host_Handle host_handle,
+ char const* port_symbol);
- /** This function is used by the UI, typically at instantiation, to get
- the numeric IDs that are mapped to certain ui:PortProtocols (see
- ui.ttl for details). If the host does not support the given
- ui:PortProtocol it MUST return LV2_UI_INVALID_PORT_PROTOCOL_ID.
-
- As a special case, when @c port_protocol_uri is LV2_UI_FLOAT_CONTROL_URI
- and ui:floatControl is listed as a required Feature for the UI, this
- function MUST return 0. The UI may assume this and skip the call.
+ /**
+ This function is used by the UI, typically at instantiation, to get
+ the numeric IDs that are mapped to certain ui:PortProtocols (see
+ ui.ttl for details). If the host does not support the given
+ ui:PortProtocol it MUST return LV2_UI_INVALID_PORT_PROTOCOL_ID.
+
+ As a special case, when @a port_protocol_uri is LV2_UI_FLOAT_CONTROL_URI
+ and ui:floatControl is listed as a required Feature for the UI, this
+ function MUST return 0. The UI may assume this and skip the call.
- @param host_handle The LV2_UI_Host_Handle that was passed to the UI's
- instantiate() function.
- @param port_protocol_uri The URI of the ui:PortProtocol.
- */
- uint32_t (*port_protocol_id)(LV2_UI_Host_Handle host_handle,
- char const* port_protocol_uri);
+ @param host_handle The @a host_handle that was passed to the UI's
+ instantiate() function.
+ @param port_protocol_uri The URI of the ui:PortProtocol.
+ */
+ uint32_t (*port_protocol_id)(LV2_UI_Host_Handle host_handle,
+ char const* port_protocol_uri);
- /** Add a port subscription. This means that the host will call the UI's
- port_event() function when the port value changes (as defined by
- the PortProtocol).
+ /**
+ Subscribe to updates for a port.
+ This means that the host will call the UI's port_event() function when
+ the port value changes (as defined by the PortProtocol).
- Calling this function with the same @c port_index and @c port_protocol
- as an already active subscription has no effect.
+ Calling this function with the same @a port_index and @a port_protocol
+ as an already active subscription has no effect.
- @param host_handle The LV2_UI_Host_Handle that was passed to the UI's
- instantiate() function.
- @param port_index The index for the port, as returned by port_index().
- @param port_protocol The numeric ID for the PortProtocol, as
- returned by port_protocol_id.
- */
- void (*add_port_subscription)(LV2_UI_Host_Handle host_handle,
- uint32_t port_index,
- uint32_t port_protocol);
-
- /** Remove a port subscription that has been added previously using
- add_port_subscription, i.e. tell the host to stop calling port_event()
- when the port value changes.
+ @param host_handle The @a host_handle that was passed to the UI's
+ instantiate() function.
+ @param port_index The index of the port, as returned by port_index().
+ @param port_protocol The numeric ID of the PortProtocol, as
+ returned by port_protocol_id().
+ */
+ void (*add_port_subscription)(LV2_UI_Host_Handle host_handle,
+ uint32_t port_index,
+ uint32_t port_protocol);
+
+ /**
+ Unsubscribe to updates for a port.
+ This means that the host will cease calling calling port_event() when
+ the port value changes.
- Calling this function with a @c port_index and @c port_protocol that
- does not define an active port subscription has no effect.
+ Calling this function with a @a port_index and @a port_protocol that
+ does not refer to an active port subscription has no effect.
- @param host_handle The LV2_UI_Host_Handle that was passed to the UI's
- instantiate() function.
- @param port_index The index for the port, as returned by port_index().
- @param port_protocol The numeric ID for the PortProtocol, as
- returned by port_protocol_id.
- */
- void (*remove_port_subscription)(LV2_UI_Host_Handle host_handle,
- uint32_t port_index,
- uint32_t port_protocol);
+ @param host_handle The @a host_handle that was passed to the UI's
+ instantiate() function.
+ @param port_index The index of the port, as returned by port_index().
+ @param port_protocol The numeric ID of the PortProtocol, as
+ returned by port_protocol_id().
+ */
+ void (*remove_port_subscription)(LV2_UI_Host_Handle host_handle,
+ uint32_t port_index,
+ uint32_t port_protocol);
} LV2_UI_Host_Descriptor;
-
-
-/** This struct contains the implementation of an UI. A pointer to an
- object of this type is returned by the lv2ui_descriptor() function.
+/**
+ 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 _LV2_UI_Descriptor {
- /** The URI for this UI (not for the plugin it controls). */
- char const* URI;
+ /**
+ The URI for this UI (not for the plugin it controls).
+ */
+ char const* 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 host_descriptor A pointer to an object that contains function
- pointers that the UI instance should use to
- control the plugin instance. This pointer MUST
- be valid until cleanup() is called for this UI
- instance.
- @param host_handle A handle that the host may use to reference internal
- data. It should be passed as the first parameter
- to the function pointers in @c host_descriptor, and
- MUST NOT be interpreted in any other way by the UI.
- @param features A NULL-terminated 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.
- */
- LV2_UI_Handle (*instantiate)(struct _LV2_UI_Descriptor const* descriptor,
- char const* plugin_uri,
- char const* bundle_path,
- LV2_UI_Host_Descriptor const* host_descriptor,
- LV2_UI_Host_Handle host_handle,
- LV2_Feature const* const* features);
-
- /** Return the widget pointer for the UI object. This MUST return the
- same value during the entire lifetime of the UI object.
- */
- LV2_UI_Widget (*get_widget)(LV2_UI_Handle ui);
-
- /** Destroy the UI object and the associated widget. The host must not try
- to access the widget after calling this function.
- */
- void (*cleanup)(LV2_UI_Handle ui);
+ /**
+ 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 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 that
+ references this shared object file, with trailing separator (e.g. '/').
+
+ @param host_descriptor A pointer to an object that contains function
+ pointers that the UI instance should use to control the plugin
+ instance. This pointer MUST be valid until cleanup() is called for this
+ UI instance.
+
+ @param host_handle A handle that the host may use to reference internal
+ data. It MUST be passed as the first parameter to the function
+ pointers in @a host_descriptor, and MUST NOT be interpreted in any other
+ way by the UI.
+
+ @param features A NULL-terminated 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; @a features will probably not be the same array as the one the
+ plugin host passes to a plugin.
+ */
+ LV2_UI_Handle (*instantiate)(struct _LV2_UI_Descriptor const* descriptor,
+ char const* plugin_uri,
+ char const* bundle_path,
+ LV2_UI_Host_Descriptor const* host_descriptor,
+ LV2_UI_Host_Handle host_handle,
+ LV2_Feature const* const* features);
+
+ /**
+ Return the widget pointer for the UI object.
+ This MUST return the same value during the entire lifetime of the UI
+ object.
+ */
+ LV2_UI_Widget (*get_widget)(LV2_UI_Handle ui);
+
+ /**
+ Destroy the UI object and the associated widget.
+ The host must not try to access the widget after calling this function.
+ */
+ void (*cleanup)(LV2_UI_Handle ui);
- /** This is called by the host when something happens at a plugin port that
- a subscription has been added for using
- LV2_UI_Host_Descriptor::add_port_subscription().
+ /**
+ Notify the UI that something has happened to a subscribed port.
+
+ This is called by the host when something happens at a plugin port that
+ has been subscribed to using
+ LV2_UI_Host_Descriptor::add_port_subscription().
- 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.
+ The @a 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.
- @param ui A handle for the UI object.
- @param port_index The index of the port for which something has
- happened as returned by
- LV2_UI_Host_Descriptor::port_index().
- @param buffer_size The size of the data buffer in bytes.
- @param port_protocol The format of the data buffer, as returned by
- LV2_UI_Host_Descriptor::port_protocol_id().
- @param buffer A pointer to the data buffer.
- */
- void (*port_event)(LV2_UI_Handle ui,
- uint32_t port_index,
- uint32_t buffer_size,
- uint32_t port_protocol,
- void const* buffer);
+ @param ui A handle for the UI object.
+ @param port_index The index of the port that has changed, as returned by
+ LV2_UI_Host_Descriptor::port_index().
+ @param buffer_size The size of the data buffer in bytes.
+ @param port_protocol The format of the data buffer, as returned by
+ LV2_UI_Host_Descriptor::port_protocol_id().
+ @param buffer A pointer to the data buffer.
+ */
+ void (*port_event)(LV2_UI_Handle ui,
+ uint32_t port_index,
+ uint32_t buffer_size,
+ uint32_t port_protocol,
+ void const* 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.
- */
- void const* (*extension_data)(char const* uri);
+ /**
+ Return a data structure associated with an extension URI.
-} LV2_UI_Descriptor;
+ This facility can be used by extensions to extend the LV2_UI_Descriptor
+ API. This function adheres to the same rules as
+ LV2_Descriptor::extension_data, except it applies to UIs rather than
+ plugins.
+ */
+ void const* (*extension_data)(char const* uri);
+} LV2_UI_Descriptor;
+/**
+ Prototype for UI accessor function.
-/** 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 LV2_UI_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.
+ This function follows the same rules as lv2_desciprotr(), except it applies
+ to UIs rather than plugins.
*/
LV2_UI_Descriptor const* lv2ui_descriptor(uint32_t index);
-
-/** This is the type of the lv2ui_descriptor() function. */
+/**
+ Type of the lv2ui_descriptor() function in a UI library.
+*/
typedef LV2_UI_Descriptor const* (*LV2_UI_DescriptorFunction)(uint32_t index);
-
-
#ifdef __cplusplus
}
#endif
-
-#endif
+#endif /* LV2_UI_H */
diff --git a/ext/ui.lv2/ui.ttl b/ext/ui.lv2/ui.ttl
index 00f4f4b..fdd9ed6 100644
--- a/ext/ui.lv2/ui.ttl
+++ b/ext/ui.lv2/ui.ttl
@@ -1,8 +1,7 @@
-# In-process UI extension
-#
+# LV2 UI Extension
# Copyright (C) 2010-2011 Lars Luthman <mail@larsluthman.net>
#
-# based on lv2.ttl, which is
+# Based on lv2.ttl, which is
# Copyright (C) 2006-2008 Steve Harris, David Robillard
#
# This extension should be considered a replacement for the earlier
@@ -29,7 +28,7 @@
# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
-@prefix ui: <http://lv2plug.in/ns/ext/ui#>.
+@prefix ui: <http://lv2plug.in/ns/ext/ui#>.
@prefix lv2: <http://lv2plug.in/ns/lv2core#>.
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@@ -38,7 +37,7 @@
<http://lv2plug.in/ns/ext/ui> a lv2:Specification ;
doap:license <http://usefulinc.com/doap/licenses/mit>;
- doap:name "LV2 in-process UI" ;
+ doap:name "LV2 UI" ;
doap:release [
doap:revision "0.1" ;
doap:created "2011-03-26"
@@ -53,48 +52,43 @@
plugins. The UIs are code that reside in shared object files in an LV2
bundle and are referenced in the RDF data using the triples
<pre>
- @prefix ui: &lt;http://lv2plug.in/ns/ext/ui#&gt; .
- &lt;http://my.pluginui&gt; a ui-gtk:GtkUI ;
- lv2:appliesTo &lt;http://my.plugin&gt; ;
- ui:binary &lt;myui.so&gt; .
+ @prefix ui: &lt;http://lv2plug.in/ns/ext/ui#&gt; .
+ @prefix ui-gtk: &lt;http://lv2plug.in/ns/ext/ui-gtk#&gt; .
+ &lt;http://example.org/my-ui&gt; a ui-gtk:GtkUI ;
+ lv2:appliesTo &lt;http://example.org/my-plugin&gt; ;
+ ui:binary &lt;my-ui.so&gt; .
</pre>
-where &lt;http://my.plugin&gt; is the URI of the plugin,
-&lt;http://my.pluginui&gt; is
-the URI of the plugin UI and &lt;myui.so&gt; 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.
-</p>
+where <code>http://example.org/my-plugin</code> is the URI of the plugin,
+<code>http://example.org/my-ui</code> is the URI of the plugin UI and
+<code>my-ui.so</code> 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.</p>
<p>A UI MUST specify its class in the RDF data and the class MUST be a proper
-subclass of ui:UI, in this case ui-gtk: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).
-</p>
+subclass of ui:UI, in this case ui-gtk: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).</p>
<p>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. It is also possible to have one
-UI that works with several different plugins.
-</p>
+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. It is also possible to have one UI that
+works with several different plugins.</p>
<p>UIs should also be written in such a way that the host may load several
instances of an UI, or different UIs, and use them with the same plugin
-instance.
-</p>
+instance.</p>
<p>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 do 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 <b>not</b> 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 the
-header lv2_ui.h is all you can expect to work.
-</p>
+code and the process that loads the shared object file containing the actual
+plugin implementation do 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 <b>not</b> 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 the header ui.h is all you
+can expect to work.</p>
""".
##############