feature(modifiers): add explicit modifiers

this makes LS(LEFT_CONTROL) work as if shift and control were both
pressed explicitly. Previously, the left shift would have been released
as soon as another key was pressed. The implicit behavior is useful in
case of LS(NUMBER_1) when rolling over to other keys.

Also see #361.

2 files changed, 13 insertions, 4 deletions

diff --git a/app/include/zmk/events/keycode_state_changed.h b/app/include/zmk/events/keycode_state_changed.h
index 031169d..466bbd7 100644
--- a/app/include/zmk/events/keycode_state_changed.h
+++ b/app/include/zmk/events/keycode_state_changed.h
@@ -7,8 +7,6 @@
 #pragma once
 
 #include <zephyr.h>
-#include <dt-bindings/zmk/modifiers.h>
-#include <dt-bindings/zmk/hid_usage_pages.h>
 #include <zmk/event_manager.h>
 #include <zmk/keys.h>
 
@@ -16,6 +14,7 @@ struct zmk_keycode_state_changed {
     uint16_t usage_page;
     uint32_t keycode;
     uint8_t implicit_modifiers;
+    uint8_t explicit_modifiers;
     bool state;
     int64_t timestamp;
 };
@@ -26,16 +25,24 @@ static inline struct zmk_keycode_state_changed_event *
 zmk_keycode_state_changed_from_encoded(uint32_t encoded, bool pressed, int64_t timestamp) {
     uint16_t page = HID_USAGE_PAGE(encoded) & 0xFF;
     uint16_t id = HID_USAGE_ID(encoded);
-    zmk_mod_flags_t implicit_mods = SELECT_MODS(encoded);
+    uint8_t implicit_modifiers = 0x00;
+    uint8_t explicit_modifiers = 0x00;
 
     if (!page) {
         page = HID_USAGE_KEY;
     }
 
+    if (is_mod(page, id)) {
+        explicit_modifiers = SELECT_MODS(encoded);
+    } else {
+        implicit_modifiers = SELECT_MODS(encoded);
+    }
+
     return new_zmk_keycode_state_changed(
         (struct zmk_keycode_state_changed){.usage_page = page,
                                            .keycode = id,
-                                           .implicit_modifiers = implicit_mods,
+                                           .implicit_modifiers = implicit_modifiers,
+                                           .explicit_modifiers = explicit_modifiers,
                                            .state = pressed,
                                            .timestamp = timestamp});
 }
diff --git a/app/include/zmk/hid.h b/app/include/zmk/hid.h
index aca3cc4..5aa004c 100644
--- a/app/include/zmk/hid.h
+++ b/app/include/zmk/hid.h
@@ -169,6 +169,8 @@ struct zmk_hid_consumer_report {
 zmk_mod_flags_t zmk_hid_get_explicit_mods();
 int zmk_hid_register_mod(zmk_mod_t modifier);
 int zmk_hid_unregister_mod(zmk_mod_t modifier);
+int zmk_hid_register_mods(zmk_mod_flags_t explicit_modifiers);
+int zmk_hid_unregister_mods(zmk_mod_flags_t explicit_modifiers);
 int zmk_hid_implicit_modifiers_press(zmk_mod_flags_t implicit_modifiers);
 int zmk_hid_implicit_modifiers_release();
 int zmk_hid_keyboard_press(zmk_key_t key);