tap-dance: key + layer helper

This adds the `ACTION_TAP_DANCE_DUAL_ROLE` helper, which makes it easy to have
keys that act as a key on the first tap, and as a layer toggle on the second.

Fixes #1532, reported by @Ptomerty.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/quantum/process_keycode/process_tap_dance.c b/quantum/process_keycode/process_tap_dance.c
index 4fd45810b..00870c4e7 100644
--- a/quantum/process_keycode/process_tap_dance.c
+++ b/quantum/process_keycode/process_tap_dance.c
@@ -41,6 +41,24 @@ void qk_tap_dance_pair_reset (qk_tap_dance_state_t *state, void *user_data) {
   }
 }
 
+void qk_tap_dance_dual_role_finished (qk_tap_dance_state_t *state, void *user_data) {
+  qk_tap_dance_dual_role_t *pair = (qk_tap_dance_dual_role_t *)user_data;
+
+  if (state->count == 1) {
+    register_code16 (pair->kc);
+  } else if (state->count == 2) {
+    layer_invert (pair->layer);
+  }
+}
+
+void qk_tap_dance_dual_role_reset (qk_tap_dance_state_t *state, void *user_data) {
+  qk_tap_dance_dual_role_t *pair = (qk_tap_dance_dual_role_t *)user_data;
+
+  if (state->count == 1) {
+    unregister_code16 (pair->kc);
+  }
+}
+
 static inline void _process_tap_dance_action_fn (qk_tap_dance_state_t *state,
                                                  void *user_data,
                                                  qk_tap_dance_user_fn_t fn)