Add per-event user hook function to QMK

tmk_core/common/action.c

@@ -53,6 +53,9 @@ void action_exec(keyevent_t event)
 #endif
 }
 
+__attribute__ ((weak))
+void process_action_user(keyrecord_t *record) {}
+
 void process_action(keyrecord_t *record)
 {
     keyevent_t event = record->event;
@@ -62,6 +65,8 @@ void process_action(keyrecord_t *record)
 
     if (IS_NOEVENT(event)) { return; }
 
+    process_action_user(record);
+
     action_t action = layer_switch_get_action(event.key);
     dprint("ACTION: "); debug_action(action);
 #ifndef NO_ACTION_LAYER

tmk_core/common/action.h

@@ -58,6 +58,9 @@ const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt);
 /* user defined special function */
 void action_function(keyrecord_t *record, uint8_t id, uint8_t opt);
 
+/* user-defined (pre)processing of each key event */
+void process_action_user(keyrecord_t *record);
+
 /* Utilities for actions.  */
 void process_action(keyrecord_t *record);
 void register_code(uint8_t code);