Per Key Leader Timing Option (#4026)

* leader changes to enable per key timing option

* Changes requested to docs for @drashna

* Changes requested by @drashna

docs/config_options.md

@@ -143,6 +143,8 @@ If you define these options you will enable the associated feature, which may in
   * Breaks any Tap Toggle functionality (`TT` or the One Shot Tap Toggle)
 * `#define LEADER_TIMEOUT 300`
   * how long before the leader key times out
+* `#define LEADER_PER_KEY_TIMING`
+  * sets the timer for leader key chords to run on each key press rather than overall
 * `#define ONESHOT_TIMEOUT 300`
   * how long before oneshot times out
 * `#define ONESHOT_TAP_TOGGLE 2`
@@ -252,6 +254,8 @@ Use these to enable or disable building certain features. The more you have enab
   * Enable the audio subsystem.
 * `RGBLIGHT_ENABLE`
   * Enable keyboard underlight functionality
+* `LEADER_ENABLE`
+  * Enable leader key chording
 * `MIDI_ENABLE`
   * MIDI controls
 * `UNICODE_ENABLE`

docs/feature_leader_key.md

@@ -47,3 +47,26 @@ To add support for Leader Key you simply need to add a single line to your keyma
 ```
 LEADER_ENABLE = yes
 ```
+
+## Per Key Timing on Leader keys
+
+Rather than relying on an incredibly high timeout for long leader key strings or those of us without 200wpm typing skills, we can enable per key timing to ensure that each key pressed provides us with more time to finish our stroke. This is incredibly helpful with leader key emulation of tap dance (read: multiple taps of the same key like C, C, C).
+
+In order to enable this, place this in your `config.h`:
+```
+#define LEADER_PER_KEY_TIMING
+```
+
+After this, it's recommended that you lower your `LEADER_TIMEOUT` to something less that 300ms.
+
+```
+#define LEADER_TIMEOUT 250
+```
+
+Now, something like this won't seem impossible to do without a 1000MS leader key timeout:
+
+```
+SEQ_THREE_KEYS(KC_C, KC_C, KC_C) {
+  SEND_STRING("Per key timing is great!!!");
+}
+```

quantum/process_keycode/process_leader.c

@@ -38,9 +38,15 @@ uint8_t leader_sequence_size = 0;
 bool process_leader(uint16_t keycode, keyrecord_t *record) {
   // Leader key set-up
   if (record->event.pressed) {
+#ifdef LEADER_PER_KEY_TIMING
+    leader_time = timer_read();
+#endif
     if (!leading && keycode == KC_LEAD) {
       leader_start();
       leading = true;
+#ifndef LEADER_PER_KEY_TIMING
+      leader_time = timer_read();
+#endif
       leader_time = timer_read();
       leader_sequence_size = 0;
       leader_sequence[0] = 0;