juce/source/src/audio/plugin_client/LV2/lv2_ui.h

   1 /*
   2   LV2 UI Extension
   3   Copyright 2009-2011 David Robillard <d@drobilla.net>
   4   Copyright 2006-2008 Lars Luthman <lars.luthman@gmail.com>
   5
   6   Permission to use, copy, modify, and/or distribute this software for any
   7   purpose with or without fee is hereby granted, provided that the above
   8   copyright notice and this permission notice appear in all copies.
   9
  10   THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17 */
  18
  19 /**
  20  * @file
  21  * C header for the LV2 UI extension <http://lv2plug.in/ns/extensions/ui>.
  22  */
  23
  24 #ifndef LV2_UI_H
  25 #define LV2_UI_H
  26
  27 #include "lv2.h"
  28
  29 #define LV2_UI_URI "http://lv2plug.in/ns/extensions/ui"
  30
  31 #ifdef __cplusplus
  32 extern "C" {
  33 #endif
  34
  35 /**
  36    A pointer to some widget or other type of UI handle.
  37
  38    The actual type is defined by the type URI of the UI.  All the functionality
  39    provided by this extension is toolkit independent, the host only needs to
  40    pass the necessary callbacks and display the widget, if possible.  Plugins
  41    may have several UIs, in various toolkits.
  42 */
  43 typedef void* LV2UI_Widget;
  44
  45 /**
  46    A pointer to a particular instance of a UI.
  47
  48    It is valid to compare this to NULL (0 for C++) but otherwise the host MUST
  49    not attempt to interpret it.  The UI plugin may use it to reference internal
  50    instance data.
  51 */
  52 typedef void* LV2UI_Handle;
  53
  54 /**
  55    A pointer to a particular plugin controller, provided by the host.
  56
  57    It is valid to compare this to NULL (0 for C++) but otherwise the UI plugin
  58    MUST NOT attempt to interpret it.  The host may use it to reference internal
  59    instance data.
  60 */
  61 typedef void* LV2UI_Controller;
  62
  63 /**
  64    The type of the host-provided function that the UI can use to
  65    send data to a plugin's input ports.
  66
  67    The @c buffer parameter must point to a block of data, @c buffer_size bytes
  68    large.  The contents of this buffer and what the host should do with it
  69    depends on the value of the @c format parameter.
  70
  71    The @c format parameter should either be 0 or a numeric ID for a "Transfer
  72    mechanism".  Transfer mechanisms are Features and may be defined in
  73    meta-extensions.  They specify how to translate the data buffers passed to
  74    this function to input data for the plugin ports.  If a UI wishes to write
  75    data to an input port, it must list a transfer mechanism Feature for that
  76    port's class as an optional or required feature (depending on whether the UI
  77    will work without being able to write to that port or not).  The only
  78    exception is when the UI wants to write single float values to input ports
  79    of the class lv2:ControlPort, in which case @c buffer_size should always be
  80    4, the buffer should always contain a single IEEE-754 float, and @c format
  81    should be 0.
  82
  83    The numeric IDs for the transfer mechanisms are provided by a URI-to-integer
  84    mapping function provided by the host, using the URI Map feature
  85    <http://lv2plug.in/ns/ext/uri-map> with the map URI
  86    "http://lv2plug.in/ns/extensions/ui".  Thus a UI that requires transfer
  87    mechanism features also requires the URI Map feature, but this is implicit -
  88    the UI does not have to list the URI map feature as a required or optional
  89    feature in it's RDF data.
  90
  91    An UI MUST NOT pass a @c format parameter value (except 0) that has not been
  92    returned by the host-provided URI mapping function for a host-supported
  93    transfer mechanism feature URI.
  94
  95    The UI MUST NOT try to write to a port for which there is no specified
  96    transfer mechanism, or to an output port.  The UI is responsible for
  97    allocating the buffer and deallocating it after the call.
  98 */
  99 typedef void (*LV2UI_Write_Function)(LV2UI_Controller controller,
 100                                      uint32_t         port_index,
 101                                      uint32_t         buffer_size,
 102                                      uint32_t         format,
 103                                      const void*      buffer);
 104
 105 /**
 106    The implementation of a UI.
 107
 108    A pointer to an object of this type is returned by the lv2ui_descriptor()
 109    function.
 110 */
 111 typedef struct _LV2UI_Descriptor {
 112   /**
 113      The URI for this UI (not for the plugin it controls).
 114   */
 115   const char* URI;
 116
 117   /**
 118      Create a new UI object and return a handle to it.  This function works
 119      similarly to the instantiate() member in LV2_Descriptor.
 120
 121      @param descriptor The descriptor for the UI that you want to instantiate.
 122
 123      @param plugin_uri The URI of the plugin that this UI will control.
 124
 125      @param bundle_path The path to the bundle containing the RDF data file
 126      that references this shared object file, including the trailing '/'.
 127
 128      @param write_function A function provided by the host that the UI can use
 129      to send data to the plugin's input ports.
 130
 131      @param controller A handle for the plugin instance that should be passed
 132      as the first parameter of @c write_function.
 133
 134      @param widget A pointer to an LV2UI_Widget.  The UI will write a widget
 135      pointer to this location (what type of widget depends on the RDF class of
 136      the UI) that will be the main UI widget.
 137
 138      @param features An array of LV2_Feature pointers.  The host must pass all
 139      feature URIs that it and the UI supports and any additional data, just
 140      like in the LV2 plugin instantiate() function.  Note that UI features and
 141      plugin features are NOT necessarily the same, they just share the same
 142      data structure - this will probably not be the same array as the one the
 143      plugin host passes to a plugin.
 144
 145   */
 146   LV2UI_Handle (*instantiate)(const struct _LV2UI_Descriptor* descriptor,
 147                               const char*                     plugin_uri,
 148                               const char*                     bundle_path,
 149                               LV2UI_Write_Function            write_function,
 150                               LV2UI_Controller                controller,
 151                               LV2UI_Widget*                   widget,
 152                               const LV2_Feature* const*       features);
 153
 154
 155   /**
 156      Destroy the UI object and the associated widget. The host must not try
 157      to access the widget after calling this function.
 158    */
 159   void (*cleanup)(LV2UI_Handle ui);
 160
 161   /**
 162      Tell the UI that something interesting has happened at a plugin port.
 163
 164      What is interesting and how it is written to the buffer passed to this
 165      function is defined by the @c format parameter, which has the same meaning
 166      as in LV2UI_Write_Function.  The only exception is ports of the class
 167      lv2:ControlPort, for which this function should be called when the port
 168      value changes (it does not have to be called for every single change if
 169      the host's UI thread has problems keeping up with the thread the plugin is
 170      running in), @c buffer_size should be 4, the buffer should contain a
 171      single IEEE-754 float, and @c format should be 0.
 172
 173      By default, the host should only call this function for input ports of the
 174      lv2:ControlPort class.  However, the default setting can be modified by
 175      using the following URIs in the UI's RDF data:
 176      <pre>
 177      uiext:portNotification
 178      uiext:noPortNotification
 179      uiext:plugin
 180      uiext:portIndex
 181      </pre>
 182      For example, if you want the UI with uri
 183      <code><http://my.pluginui></code> for the plugin with URI
 184      <code><http://my.plugin></code> to get notified when the value of the
 185      output control port with index 4 changes, you would use the following
 186      in the RDF for your UI:
 187      <pre>
 188      <http://my.pluginui> uiext:portNotification [ uiext:plugin <http://my.plugin> ;
 189      uiext:portIndex 4 ] .
 190      </pre>
 191      and similarly with <code>uiext:noPortNotification</code> if you wanted
 192      to prevent notifications for a port for which it would be on by default
 193      otherwise. The UI is not allowed to request notifications for ports of
 194      types for which no transfer mechanism is specified, if it does it should
 195      be considered broken and the host should not load it.
 196
 197      The @c buffer is only valid during the time of this function call, so if
 198      the UI wants to keep it for later use it has to copy the contents to an
 199      internal buffer.
 200
 201      This member may be set to NULL if the UI is not interested in any
 202      port events.
 203   */
 204   void (*port_event)(LV2UI_Handle ui,
 205                      uint32_t     port_index,
 206                      uint32_t     buffer_size,
 207                      uint32_t     format,
 208                      const void*  buffer);
 209
 210   /**
 211      Return a data structure associated with an extension URI, for example
 212      a struct containing additional function pointers.
 213
 214      Avoid returning function pointers directly since standard C/C++ has no
 215      valid way of casting a void* to a function pointer. This member may be set
 216      to NULL if the UI is not interested in supporting any extensions. This is
 217      similar to the extension_data() member in LV2_Descriptor.
 218   */
 219   const void* (*extension_data)(const char* uri);
 220
 221 } LV2UI_Descriptor;
 222
 223 /**
 224    A plugin UI programmer must include a function called "lv2ui_descriptor"
 225    with the following function prototype within the shared object file.  This
 226    function will have C-style linkage (if you are using C++ this is taken care
 227    of by the 'extern "C"' clause at the top of the file).  This function will
 228    be accessed by the UI host using the @c dlsym() function and called to get a
 229    LV2UI_UIDescriptor for the wanted plugin.
 230
 231    Just like lv2_descriptor(), this function takes an index parameter.  The
 232    index should only be used for enumeration and not as any sort of ID number -
 233    the host should just iterate from 0 and upwards until the function returns
 234    NULL or a descriptor with an URI matching the one the host is looking for.
 235 */
 236 const LV2UI_Descriptor* lv2ui_descriptor(uint32_t index);
 237
 238 /**
 239    The type of the lv2ui_descriptor() function.
 240 */
 241 typedef const LV2UI_Descriptor* (*LV2UI_DescriptorFunction)(uint32_t index);
 242
 243 #ifdef __cplusplus
 244 }
 245 #endif
 246
 247 #endif /* LV2_UI_H */