Implement the plugin side if IComponentHandler3

src/plugin/bridges/vst3-impls/plugin-proxy.cpp

@@ -39,6 +39,26 @@ Vst3PluginProxyImpl::queryInterface(const Steinberg::TUID _iid, void** obj) {
     return result;
 }
 
+size_t Vst3PluginProxyImpl::register_context_menu(
+    Steinberg::IPtr<Steinberg::Vst::IContextMenu> menu) {
+    std::lock_guard lock(context_menus_mutex);
+
+    const size_t context_menu_id = current_context_menu_id.fetch_add(1);
+    context_menus.emplace(context_menu_id, std::move(menu));
+
+    return context_menu_id;
+}
+
+/**
+ * Unregister a context menu using the ID generated by a previous call to
+ * `register_context_menu()`. This will release the context menu object
+ * returned by the host.
+ */
+bool Vst3PluginProxyImpl::unregister_context_menu(size_t context_menu_id) {
+    std::lock_guard lock(context_menus_mutex);
+    return context_menus.erase(context_menu_id);
+}
+
 tresult PLUGIN_API Vst3PluginProxyImpl::setAudioPresentationLatencySamples(
     Steinberg::Vst::BusDirection dir,
     int32 busIndex,
@@ -373,6 +393,7 @@ tresult PLUGIN_API Vst3PluginProxyImpl::setComponentHandler(
         // Automatically converted smart pointers for when the plugin performs a
         // callback later
         component_handler_2 = component_handler;
+        component_handler_3 = component_handler;
         unit_handler = component_handler;
 
         return bridge.send_message(YaEditController::SetComponentHandler{

src/plugin/bridges/vst3-impls/plugin-proxy.h

@@ -38,6 +38,22 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
     tresult PLUGIN_API queryInterface(const Steinberg::TUID _iid,
                                       void** obj) override;
 
+    /**
+     * Add a context menu created by a call to
+     * `IComponentHandler3::createContextMenu` to our list of registered cotnext
+     * menus. This way we can refer to it later when the plugin calls a function
+     * on the proxy object we'll create for it.
+     */
+    size_t register_context_menu(
+        Steinberg::IPtr<Steinberg::Vst::IContextMenu> menu);
+
+    /**
+     * Unregister a context menu using the ID generated by a previous call to
+     * `register_context_menu()`. This will release the context menu object
+     * returned by the host.
+     */
+    bool unregister_context_menu(size_t context_menu_id);
+
     // From `IAudioPresentationLatency`
     tresult PLUGIN_API
     setAudioPresentationLatencySamples(Steinberg::Vst::BusDirection dir,
@@ -242,6 +258,21 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
      */
     Vst3PlugViewProxyImpl* last_created_plug_view = nullptr;
 
+    /**
+     * All context menus created by this object through
+     * `IComponentHandler3::createContextMenu()`. We'll generate a unique
+     * identifier for each context menu just like we do for plugin objects. When
+     * the plugin drops the context menu object, we'll also remove the
+     * corresponding entry for this map causing the original pointer returned by
+     * the host to get dropped a well.
+     *
+     * @see Vst3PluginProxyImpl::register_context_menu
+     * @see Vst3PluginProxyImpl::unregister_context_menu
+     */
+    std::map<size_t, Steinberg::IPtr<Steinberg::Vst::IContextMenu>>
+        context_menus;
+    std::mutex context_menus_mutex;
+
     // The following pointers are cast from `host_context` if
     // `IPluginBase::initialize()` has been called
 
@@ -252,6 +283,8 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
 
     Steinberg::FUnknownPtr<Steinberg::Vst::IComponentHandler2>
         component_handler_2;
+    Steinberg::FUnknownPtr<Steinberg::Vst::IComponentHandler3>
+        component_handler_3;
     Steinberg::FUnknownPtr<Steinberg::Vst::IUnitHandler> unit_handler;
 
    private:
@@ -265,4 +298,12 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
      * but for the sake of correctness we will.
      */
     Steinberg::IPtr<Steinberg::FUnknown> host_context;
+
+    /**
+     * Used to assign unique identifiers to context menus created by
+     * `IComponentHandler3::CreateContextMenu`.
+     *
+     * @related Vst3PluginProxyImpl::register_context_menu
+     */
+    std::atomic_size_t current_context_menu_id;
 };

src/plugin/bridges/vst3.cpp

@@ -102,6 +102,43 @@ Vst3PluginBridge::Vst3PluginBridge()
                         .get()
                         .component_handler_2->finishGroupEdit();
                 },
+                [&](const YaComponentHandler3::CreateContextMenu& request)
+                    -> YaComponentHandler3::CreateContextMenu::Response {
+                    // XXX: As mentioned elsewhere, since VST3 only supports a
+                    //      single plug view type at the moment we'll just
+                    //      assume that this function is called from the last
+                    //      (and only) `IPlugView*` instance returned by the
+                    //      plugin.
+                    Vst3PlugViewProxyImpl* plug_view =
+                        plugin_proxies.at(request.owner_instance_id)
+                            .get()
+                            .last_created_plug_view;
+
+                    Steinberg::IPtr<Steinberg::Vst::IContextMenu> context_menu =
+                        Steinberg::owned(
+                            plugin_proxies.at(request.owner_instance_id)
+                                .get()
+                                .component_handler_3->createContextMenu(
+                                    plug_view, request.param_id
+                                                   ? &*request.param_id
+                                                   : nullptr));
+
+                    if (context_menu) {
+                        const size_t context_menu_id =
+                            plugin_proxies.at(request.owner_instance_id)
+                                .get()
+                                .register_context_menu(std::move(context_menu));
+
+                        return YaComponentHandler3::CreateContextMenuResponse{
+                            .context_menu_args =
+                                Vst3ContextMenuProxy::ConstructArgs(
+                                    context_menu, request.owner_instance_id,
+                                    context_menu_id)};
+                    } else {
+                        return YaComponentHandler3::CreateContextMenuResponse{
+                            .context_menu_args = std::nullopt};
+                    }
+                },
                 [&](YaConnectionPoint::Notify& request)
                     -> YaConnectionPoint::Notify::Response {
                     return plugin_proxies.at(request.instance_id)