Reduce tap dance memory usage, move state out of data (#25415)

* Use less tap dance memory.

Use dynamically allocated sparse array for tap dance state, dynamically allocate tap dance state when needed and free it when the tap dance is done.

* new approach

* Use null, check for null

* Reformat with docker

* Use uint8 with idx rather than uint16 with keycode in state

* fix accidental change

* reformat

* Add null check

* add documentation tip suggested by tzarc

* Only allow tap dance state allocation on key down, not on key up

Co-authored-by: Sergey Vlasov <sigprof@gmail.com>

* Only allow tap dance allocation on key down, not on key up

Co-authored-by: Sergey Vlasov <sigprof@gmail.com>

* add user action required section

---------

Co-authored-by: Sergey Vlasov <sigprof@gmail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/tests/tap_dance/examples.c b/tests/tap_dance/examples.c
index 4b6bdb2090..6aaf008232 100644
--- a/tests/tap_dance/examples.c
+++ b/tests/tap_dance/examples.c
@@ -81,11 +81,13 @@ typedef struct {
 
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
     tap_dance_action_t *action;
+    tap_dance_state_t* state;
 
     switch (keycode) {
         case TD(CT_CLN):
             action = tap_dance_get(QK_TAP_DANCE_GET_INDEX(keycode));
-            if (!record->event.pressed && action->state.count && !action->state.finished) {
+            state = tap_dance_get_state(QK_TAP_DANCE_GET_INDEX(keycode));
+            if (!record->event.pressed && state != NULL && state->count && !state->finished) {
                 tap_dance_tap_hold_t *tap_hold = (tap_dance_tap_hold_t *)action->user_data;
                 tap_code16(tap_hold->tap);
             }