[Core] Tri Layer Keys (#19795)

Co-authored-by: wilba <[email protected]>
Co-authored-by: Pablo Martínez <[email protected]>
Co-authored-by: Joel Challis <[email protected]>
Co-authored-by: Nick Brassel <[email protected]>

quantum/process_keycode/process_tri_layer.c

@@ -0,0 +1,30 @@
+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "process_tri_layer.h"
+#include "tri_layer.h"
+#include "action_layer.h"
+
+bool process_tri_layer(uint16_t keycode, keyrecord_t *record) {
+    switch (keycode) {
+        case QK_TRI_LAYER_LOWER:
+            if (record->event.pressed) {
+                layer_on(get_tri_layer_lower_layer());
+                update_tri_layer(get_tri_layer_lower_layer(), get_tri_layer_upper_layer(), get_tri_layer_adjust_layer());
+            } else {
+                layer_off(get_tri_layer_lower_layer());
+                update_tri_layer(get_tri_layer_lower_layer(), get_tri_layer_upper_layer(), get_tri_layer_adjust_layer());
+            }
+            return false;
+        case QK_TRI_LAYER_UPPER:
+            if (record->event.pressed) {
+                layer_on(get_tri_layer_upper_layer());
+                update_tri_layer(get_tri_layer_lower_layer(), get_tri_layer_upper_layer(), get_tri_layer_adjust_layer());
+            } else {
+                layer_off(get_tri_layer_upper_layer());
+                update_tri_layer(get_tri_layer_lower_layer(), get_tri_layer_upper_layer(), get_tri_layer_adjust_layer());
+            }
+            return false;
+    }
+    return true;
+}

quantum/process_keycode/process_tri_layer.h

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+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "action.h"
+
+/**
+ * @brief Handles tri layer behavior
+ *
+ * @param keycode the keycode
+ * @param record the key record structure
+ * @return true continue handling keycodes
+ * @return false stop handling keycodes
+ */
+bool process_tri_layer(uint16_t keycode, keyrecord_t *record);