Add poly mod config constant to ClapPlugin

Setting this will enable the 'voice-info' extension.

src/param/boolean.rs

@@ -226,7 +226,9 @@ impl BoolParam {
     /// Enable polyphonic modulation for this parameter. The ID is used to uniquely identify this
     /// parameter in [`NoteEvent::PolyModulation][crate::prelude::NoteEvent::PolyModulation`]
     /// events, and must thus be unique between _all_ polyphonically modulatable parameters. See the
-    /// event's documentation for more information on how to use this.
+    /// event's documentation on how to do this. Consider configuring the
+    /// [`ClapPlugin::CLAP_POLY_MODULATION_CONFIG`][crate::prelude::ClapPlugin::CLAP_POLY_MODULATION_CONFIG]
+    /// constant when enabling this.
     ///
     /// # Important
     ///

src/param/enums.rs

@@ -337,7 +337,9 @@ impl<T: Enum + PartialEq + 'static> EnumParam<T> {
     /// Enable polyphonic modulation for this parameter. The ID is used to uniquely identify this
     /// parameter in [`NoteEvent::PolyModulation][crate::prelude::NoteEvent::PolyModulation`]
     /// events, and must thus be unique between _all_ polyphonically modulatable parameters. See the
-    /// event's documentation for more information on how to use this.
+    /// event's documentation on how to do this. Consider configuring the
+    /// [`ClapPlugin::CLAP_POLY_MODULATION_CONFIG`][crate::prelude::ClapPlugin::CLAP_POLY_MODULATION_CONFIG]
+    /// constant when enabling this.
     ///
     /// # Important
     ///

src/param/float.rs

@@ -293,7 +293,10 @@ impl FloatParam {
 
     /// Enable polyphonic modulation for this parameter. The ID is used to uniquely identify this
     /// parameter in [`NoteEvent::PolyModulation][crate::prelude::NoteEvent::PolyModulation`]
-    /// events, and must thus be unique between _all_ polyphonically modulatable parameters.
+    /// events, and must thus be unique between _all_ polyphonically modulatable parameters. See the
+    /// event's documentation on how to do this. Consider configuring the
+    /// [`ClapPlugin::CLAP_POLY_MODULATION_CONFIG`][crate::prelude::ClapPlugin::CLAP_POLY_MODULATION_CONFIG]
+    /// constant when enabling this.
     ///
     /// # Important
     ///

src/param/integer.rs

@@ -258,7 +258,9 @@ impl IntParam {
     /// Enable polyphonic modulation for this parameter. The ID is used to uniquely identify this
     /// parameter in [`NoteEvent::PolyModulation][crate::prelude::NoteEvent::PolyModulation`]
     /// events, and must thus be unique between _all_ polyphonically modulatable parameters. See the
-    /// event's documentation for more information on how to use this.
+    /// event's documentation on how to do this. Consider configuring the
+    /// [`ClapPlugin::CLAP_POLY_MODULATION_CONFIG`][crate::prelude::ClapPlugin::CLAP_POLY_MODULATION_CONFIG]
+    /// constant when enabling this.
     ///
     /// # Important
     ///

src/plugin.rs

@@ -19,8 +19,8 @@ use crate::wrapper::clap::features::ClapFeature;
 /// This is super basic, and lots of things I didn't need or want to use yet haven't been
 /// implemented. Notable missing features include:
 ///
-/// - MIDI SysEx and MIDI2 for CLAP, note expressions and MIDI1 are already supported
+/// - MIDI SysEx and MIDI2 for CLAP, note expressions, polyphonic modulation and MIDI1 are already
-/// - Polyphonic modulation for CLAP
+///   supported
 /// - Audio thread thread pools (with host integration in CLAP)
 #[allow(unused_variables)]
 pub trait Plugin: Default + Send + Sync + 'static {
@@ -206,6 +206,9 @@ pub trait ClapPlugin: Plugin {
     /// Keywords describing the plugin. The host may use this to classify the plugin in its plugin
     /// browser.
     const CLAP_FEATURES: &'static [ClapFeature];
+
+    /// If set, this informs the host about the plugin's capabilities for polyphonic modulation.
+    const CLAP_POLY_MODULATION_CONFIG: Option<PolyModulationConfig> = None;
 }
 
 /// Provides auxiliary metadata needed for a VST3 plugin.
@@ -419,3 +422,15 @@ pub enum ProcessMode {
     /// processed.
     Offline,
 }
+
+/// Configuration for the plugin's polyphonic modulation options, if it supports .
+pub struct PolyModulationConfig {
+    /// The maximum number of voices this plugin will ever use. Call the context's
+    /// `set_current_voices()` method during initialization or audio processing to set the number of
+    /// currently active voices.
+    pub max_voices: u32,
+    /// If set to `true`, then the host may send note events for the same channel and key, but using
+    /// different voice IDs. Bitwig Studio, for instance, can use this to do voice stacking. After
+    /// enabling this, you should always prioritize using voice IDs to map note events to voices.
+    pub supports_overlapping_voices: bool,
+}