Move event handling to a common HostBridge

src/wine-host/bridges/common.h

@@ -0,0 +1,61 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020  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 "../editor.h"
+
+/**
+ * The base for the Wine plugin host bridge interface for all plugin types. This
+ * only has to be able to handle Win32 and X11 events. Implementations of this
+ * will actually host a plugin and do all the function call forwarding.
+ */
+class HostBridge {
+   public:
+    /**
+     * Handle X11 events for the editor window if it is open. This can safely be
+     * run from any thread.
+     */
+    void handle_x11_events();
+
+    /**
+     * Run the message loop for this plugin. This is only used for the
+     * individual plugin host, so that we can filter out some unnecessary timer
+     * events. When hosting multiple plugins, a simple central message loop
+     * should be used instead. This is run on a timer in the same IO context as
+     * the one that handles the events, i.e. `main_context`.
+     *
+     * Because of the way the Win32 API works we have to process events on the
+     * same thread as the one the window was created on, and that thread is the
+     * thread that's handling dispatcher calls. Some plugins will also rely on
+     * the Win32 message loop to run tasks on a timer and to defer loading, so
+     * we have to make sure to always run this loop. The only exception is a in
+     * specific situation that can cause a race condition in some plugins
+     * because of incorrect assumptions made by the plugin. See the dostring for
+     * `HostBridge::editor` for more information.
+     */
+    void handle_win32_events();
+
+   protected:
+    /**
+     * The plugin editor window. Allows embedding the plugin's editor into a
+     * Wine window, and embedding that Wine window into a window provided by the
+     * host. Should be empty when the editor is not open.
+     *
+     * @see should_postpone_message_loop
+     */
+    std::optional<Editor> editor;
+};