[client] main: add interface for modules to register key binds

client/include/interface/app.h

@@ -0,0 +1,41 @@
+/*
+Looking Glass - KVM FrameRelay (KVMFR) Client
+Copyright (C) 2017-2019 Geoffrey McRae <geoff@hostfission.com>
+https://looking-glass.hostfission.com
+
+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 2 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, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#pragma once
+
+#include <SDL2/SDL.h>
+
+typedef struct KeybindHandle * KeybindHandle;
+typedef void (*SuperEventFn)(SDL_Scancode key, void * opaque);
+
+/**
+ * Register a handler for the <super>+<key> combination
+ * @param key      The scancode to register
+ * @param callback The function to be called when the combination is pressed
+ * @param opaque   A pointer to be passed to the callback, may be NULL
+ * @retval A handle for the binding or NULL on failure.
+ *         The caller is required to release the handle via `app_release_keybind` when it is no longer required
+ */
+KeybindHandle app_register_keybind(SDL_Scancode key, SuperEventFn callback, void * opaque);
+
+/**
+ * Release an existing key binding
+ * @param handle A pointer to the keybind handle to release, may be NULL
+ */
+void app_release_keybind(KeybindHandle * handle);