Add proxy classes for IContextMenu

So we can proxy objects returned by the host during `IComponentHandler3::createContextMenu`.
2026-06-10 22:32:10 +02:00 · 2021-01-06 15:50:58 +01:00
parent 5b70e0eea6
commit fbbd2f0671
6 changed files with 286 additions and 0 deletions
@@ -0,0 +1,122 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020-2021 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include "../common.h"
+#include "context-menu/context-menu.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+
+/**
+ * An abstract class that implements `IContextMenu`, and optionally also all
+ * other VST3 interfaces an object returned by
+ * `IComponentHandler3::createContextMenu()` might implement. This is used to
+ * provide a proxy for the context menu object created by the host. The host
+ * will return a (prepopulated, although that's invisible to the plugin) context
+ * menu for right clicking on a specific parameter. The plugin can then add
+ * their own items to it, and then have it appear at the specified coordinates.
+ * Those items passed by the plugin contain callbacks that will be called when
+ * the user clicks on them. As far as I'm aware, not a single Linux VST3 host
+ * implements `IComponentHandler3` and thus provides support for these context
+ * menus.
+ *
+ * NOTE: For simplicity's sake (and because this is going to be true 100% of the
+ *       time) we'll assume a plugin can only have a single context menu open at
+ *       a time. If a host does allow creating multiple context menus for
+ *       different parameters at the same time, then we'll just have to add a
+ *       unique instance ID to the context menu.
+ */
+class Vst3ContextMenuProxy : public YaContextMenu {
+   public:
+    /**
+     * These are the arguments for constructing a `Vst3ContextMenuProxyImpl`.
+     */
+    struct ConstructArgs {
+        ConstructArgs();
+
+        /**
+         * Read from an existing object. We will try to mimic this object, so
+         * we'll support any interfaces this object also supports.
+         */
+        ConstructArgs(Steinberg::IPtr<FUnknown> object,
+                      size_t owner_instance_id);
+
+        /**
+         * The unique instance identifier of the proxy object instance this
+         * context menu has been created for.
+         */
+        native_size_t owner_instance_id;
+
+        YaContextMenu::ConstructArgs context_menu_args;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(owner_instance_id);
+            s.object(context_menu_args);
+        }
+    };
+
+    /**
+     * Instantiate this instance with arguments read from an actual component
+     * handler.
+     *
+     * This object is created as part of
+     * `IComponentHandler3::createContextMenu`, so there's no direct `Construct`
+     * message. When the object's reference count reaches zero, we should
+     * destroy the actual context menu object provided by the host using the
+     * `Destruct` message.
+     */
+    Vst3ContextMenuProxy(const ConstructArgs&& args);
+
+    /**
+     * Message to request the plugin to drop the the `IContextMenu*` returned by
+     * the host for the plugin instance with the given instance ID. Sent from
+     * the destructor of `Vst3ContextMenuProxyImpl`.
+     */
+    struct Destruct {
+        using Response = Ack;
+
+        native_size_t owner_instance_id;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(owner_instance_id);
+        }
+    };
+
+    /**
+     * When this object gets dropped, we sent a `Destruct` message to also drop
+     * the pointer to the actual `IContextMenu*` returend by the host during
+     * `IComponentHandler3::createContextMenu`.
+     */
+    virtual ~Vst3ContextMenuProxy() = 0;
+
+    DECLARE_FUNKNOWN_METHODS
+
+    /**
+     * Get the instance ID of the owner of this object.
+     */
+    inline size_t owner_instance_id() const {
+        return arguments.owner_instance_id;
+    }
+
+   private:
+    ConstructArgs arguments;
+};
+
+#pragma GCC diagnostic pop