From 8a4b430e8389eab2c174ae96ca7b721540ea2707 Mon Sep 17 00:00:00 2001
From: Nick Thompson <ncthom91@gmail.com>
Date: Sun, 14 Jan 2024 18:19:23 -0500
Subject: [PATCH] Relay graph events to webview

---
 native/LambdaTimer.h       | 28 ++++++++++++++++++++++++++++
 native/PluginProcessor.cpp | 34 ++++++++++++++++++++++++++++++++++
 native/PluginProcessor.h   |  4 ++++
 src/main.jsx               |  4 ++++
 4 files changed, 70 insertions(+)
 create mode 100644 native/LambdaTimer.h

diff --git a/native/LambdaTimer.h b/native/LambdaTimer.h
new file mode 100644
index 0000000..71081cd
--- /dev/null
+++ b/native/LambdaTimer.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <juce_core/juce_core.h>
+
+
+//==============================================================================
+// A small helper class for invoking a lambda periodically
+// via juce::Timer
+template <typename Fn>
+class LambdaTimer : public juce::Timer {
+public:
+    LambdaTimer(int rate, Fn&& f) : callback(std::move(f)) {
+        startTimerHz(rate);
+    }
+
+    ~LambdaTimer() {
+        stopTimer();
+    }
+
+    void timerCallback() override {
+        if (callback) {
+            callback();
+        }
+    }
+
+private:
+    Fn callback;
+};
diff --git a/native/PluginProcessor.cpp b/native/PluginProcessor.cpp
index 2b7ab85..1739fec 100644
--- a/native/PluginProcessor.cpp
+++ b/native/PluginProcessor.cpp
@@ -217,6 +217,11 @@ void EffectsPluginProcessor::handleAsyncUpdate()
         // TODO: This is definitely not thread-safe! It could delete a Runtime instance while
         // the real-time thread is using it. Depends on when the host will call prepareToPlay.
         runtime = std::make_unique<elem::Runtime<float>>(lastKnownSampleRate, lastKnownBlockSize);
+
+        eventsTimer = std::make_unique<LambdaTimer<std::function<void()>>>(60, [this]() {
+            dispatchGraphEvents();
+        });
+
         initJavaScriptEngine();
     }
 
@@ -371,6 +376,35 @@ void EffectsPluginProcessor::dispatchStateChange()
     jsContext.evaluate(expr);
 }
 
+void EffectsPluginProcessor::dispatchGraphEvents()
+{
+    const auto* kDispatchScript = R"script(
+(function() {
+  if (typeof globalThis.__receiveGraphEvents__ !== 'function')
+    return false;
+
+  globalThis.__receiveGraphEvents__(%);
+  return true;
+})();
+)script";
+
+    if (runtime) {
+        elem::js::Array batch;
+
+        runtime->processQueuedEvents([this, &batch](std::string const& type, elem::js::Value evt) {
+            batch.push_back(elem::js::Object({
+                {"type", type},
+                {"event", evt}
+            }));
+        });
+
+        if (auto* editor = static_cast<WebViewEditor*>(getActiveEditor())) {
+            auto expr = juce::String(kDispatchScript).replace("%", elem::js::serialize(elem::js::serialize(batch))).toStdString();
+            editor->getWebViewPtr()->evaluateJavascript(expr);
+        }
+    }
+}
+
 void EffectsPluginProcessor::dispatchError(std::string const& name, std::string const& message)
 {
     const auto* kDispatchScript = R"script(
diff --git a/native/PluginProcessor.h b/native/PluginProcessor.h
index d828257..91cdee2 100644
--- a/native/PluginProcessor.h
+++ b/native/PluginProcessor.h
@@ -6,6 +6,8 @@
 #include <choc_javascript.h>
 #include <elem/Runtime.h>
 
+#include "LambdaTimer.h"
+
 
 //==============================================================================
 class EffectsPluginProcessor
@@ -64,6 +66,7 @@ class EffectsPluginProcessor
 
     /** Internal helper for propagating processor state changes. */
     void dispatchStateChange();
+    void dispatchGraphEvents();
     void dispatchError(std::string const& name, std::string const& message);
 
 private:
@@ -78,6 +81,7 @@ class EffectsPluginProcessor
     juce::AudioBuffer<float> scratchBuffer;
 
     std::unique_ptr<elem::Runtime<float>> runtime;
+    std::unique_ptr<LambdaTimer<std::function<void()>>> eventsTimer;
 
     //==============================================================================
     // A simple "dirty list" abstraction here for propagating realtime parameter
diff --git a/src/main.jsx b/src/main.jsx
index 51ee5e6..3152a19 100644
--- a/src/main.jsx
+++ b/src/main.jsx
@@ -39,6 +39,10 @@ globalThis.__receiveStateChange__ = function(state) {
   store.setState(JSON.parse(state));
 };
 
+globalThis.__receiveGraphEvents__ = function(eventBatch) {
+  console.log(JSON.parse(eventBatch));
+};
+
 globalThis.__receiveError__ = (err) => {
   errorStore.setState({ error: err });
 };