From 4ce5f359d6e2e93c215a52fb73de3214d44267ea Mon Sep 17 00:00:00 2001
From: Robbert van der Helm <mail@robbertvanderhelm.nl>
Date: Fri, 18 Mar 2022 15:26:19 +0100
Subject: [PATCH] Add parameter setting events for vizia

---
 nih_plug_vizia/src/assets.rs  |  2 +-
 nih_plug_vizia/src/lib.rs     | 10 ++++++-
 nih_plug_vizia/src/widgets.rs | 54 +++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 nih_plug_vizia/src/widgets.rs

diff --git a/nih_plug_vizia/src/assets.rs b/nih_plug_vizia/src/assets.rs
index e8f3e385..e0ca383a 100644
--- a/nih_plug_vizia/src/assets.rs
+++ b/nih_plug_vizia/src/assets.rs
@@ -1,7 +1,7 @@
 //! Binary assets for use with `nih_plug_iced. These fonts first need to be registered by calling
 //! [`nih_plug_iced::assets::register_fonts()`][register_fonts()`].
 
-use crate::vizia::Context;
+use vizia::Context;
 
 // This module provides a re-export and simple font wrappers around the re-exported fonts.
 pub use nih_plug_assets::*;
diff --git a/nih_plug_vizia/src/lib.rs b/nih_plug_vizia/src/lib.rs
index d183b78d..b3daac9f 100644
--- a/nih_plug_vizia/src/lib.rs
+++ b/nih_plug_vizia/src/lib.rs
@@ -5,12 +5,13 @@ use crossbeam::atomic::AtomicCell;
 use nih_plug::prelude::{Editor, GuiContext, ParamSetter, ParentWindowHandle};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
-use vizia::{Application, Context, WindowDescription};
+use vizia::{Application, Context, Model, WindowDescription};
 
 // Re-export for convenience
 pub use vizia;
 
 pub mod assets;
+pub mod widgets;
 
 /// Create an [`Editor`] instance using a [`vizia`][::vizia] GUI. The [`ViziaState`] passed to this
 /// function contains the GUI's intitial size, and this is kept in sync whenever the GUI gets
@@ -88,6 +89,13 @@ impl Editor for ViziaEditor {
         let window = Application::new(window_description, move |cx| {
             let setter = ParamSetter::new(context.as_ref());
 
+            // Any widget can change the parameters by emitting `ParamEvent` events. This model will
+            // handle them automatically.
+            widgets::ParamModel {
+                context: context.clone(),
+            }
+            .build(cx);
+
             app(cx, &setter)
         })
         .with_scale_policy(
diff --git a/nih_plug_vizia/src/widgets.rs b/nih_plug_vizia/src/widgets.rs
new file mode 100644
index 00000000..3fcd712b
--- /dev/null
+++ b/nih_plug_vizia/src/widgets.rs
@@ -0,0 +1,54 @@
+//! Widgets and utilities for making widgets to integrate VIZIA with NIH-plug.
+//!
+//! # Note
+//!
+//! None of these widgets are finalized, and their sizes or looks can change at any point. Feel free
+//! to copy the widgets and modify them to your personal taste.
+
+use nih_plug::{context::GuiContext, param::internals::ParamPtr};
+use std::sync::Arc;
+
+use vizia::Model;
+
+/// An event that updates a parameter's value. Since NIH-plug manages the parameters, interacting
+/// with parameter values with VIZIA works a little different from updating any other state. These
+/// events are automatically handled by `nih_plug_vizia`.
+#[derive(Debug, Clone, Copy)]
+pub enum ParamEvent {
+    /// Begin an automation gesture for a parameter.
+    BeginSetParameter(ParamPtr),
+    /// Set a parameter to a new normalized value. This needs to be surrounded by a matching
+    /// `BeginSetParameter` and `EndSetParameter`.
+    SetParameterNormalized(ParamPtr, f32),
+    /// Reset a parameter to its default value. This needs to be surrounded by a matching
+    /// `BeginSetParameter` and `EndSetParameter`.
+    ResetParameter(ParamPtr),
+    /// End an automation gesture for a parameter.
+    EndSetParameter(ParamPtr),
+}
+
+/// Handles parameter updates for VIZIA GUIs. Registered in
+/// [`ViziaEditor::spawn()`][super::ViziaEditor::spawn()].
+pub(crate) struct ParamModel {
+    pub context: Arc<dyn GuiContext>,
+}
+
+impl Model for ParamModel {
+    fn event(&mut self, _cx: &mut vizia::Context, event: &mut vizia::Event) {
+        if let Some(param_event) = event.message.downcast() {
+            match *param_event {
+                ParamEvent::BeginSetParameter(p) => unsafe {
+                    self.context.raw_begin_set_parameter(p)
+                },
+                ParamEvent::SetParameterNormalized(p, v) => unsafe {
+                    self.context.raw_set_parameter_normalized(p, v)
+                },
+                ParamEvent::ResetParameter(p) => unsafe {
+                    let default_value = self.context.raw_default_normalized_param_value(p);
+                    self.context.raw_set_parameter_normalized(p, default_value);
+                },
+                ParamEvent::EndSetParameter(p) => unsafe { self.context.raw_end_set_parameter(p) },
+            }
+        }
+    }
+}