Add layer change event

app/CMakeLists.txt

@@ -30,6 +30,7 @@ target_sources(app PRIVATE src/sensors.c)
 target_sources(app PRIVATE src/event_manager.c)
 target_sources_ifdef(CONFIG_ZMK_EXT_POWER app PRIVATE src/ext_power_generic.c)
 target_sources(app PRIVATE src/events/position_state_changed.c)
+target_sources(app PRIVATE src/events/layer_state_changed.c)
 target_sources(app PRIVATE src/events/keycode_state_changed.c)
 target_sources(app PRIVATE src/events/modifiers_state_changed.c)
 target_sources(app PRIVATE src/events/sensor_event.c)

app/include/zmk/events/layer-state-changed.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr.h>
+#include <zmk/event-manager.h>
+
+struct layer_state_changed {
+    struct zmk_event_header header;
+    u32_t layer;
+    bool state;
+    s64_t timestamp;
+};
+
+ZMK_EVENT_DECLARE(layer_state_changed);

app/include/zmk/keymap.h

@@ -6,7 +6,10 @@
 
 #pragma once
 
+u8_t zmk_layer_default();
+u32_t zmk_layer_state();
 bool zmk_keymap_layer_active(u8_t layer);
+u8_t zmk_highest_layer_active();
 int zmk_keymap_layer_activate(u8_t layer);
 int zmk_keymap_layer_deactivate(u8_t layer);
 int zmk_keymap_layer_toggle(u8_t layer);

app/src/events/layer_state_changed.c

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <kernel.h>
+#include <zmk/events/layer-state-changed.h>
+
+ZMK_EVENT_IMPL(layer_state_changed);

app/src/keymap.c

@@ -16,6 +16,7 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
 #include <zmk/event-manager.h>
 #include <zmk/events/position-state-changed.h>
+#include <zmk/events/layer-state-changed.h>
 #include <zmk/events/sensor-event.h>
 
 static u32_t zmk_keymap_layer_state = 0;
@@ -76,17 +77,34 @@ static struct zmk_behavior_binding zmk_sensor_keymap[ZMK_KEYMAP_LAYERS_LEN]
 
 #endif /* ZMK_KEYMAP_HAS_SENSORS */
 
-#define SET_LAYER_STATE(layer, state)                                                              \
+#define SET_LAYER_STATE(new_layer, new_state)                                                      \
-    if (layer >= 32) {                                                                             \
+    if (new_layer >= 32) {                                                                         \
         return -EINVAL;                                                                            \
     }                                                                                              \
-    WRITE_BIT(zmk_keymap_layer_state, layer, state);                                               \
+    WRITE_BIT(zmk_keymap_layer_state, new_layer, new_state);                                       \
+    struct layer_state_changed *ev = new_layer_state_changed();                                    \
+    ev->layer = new_layer;                                                                         \
+    ev->state = new_state;                                                                         \
+    ZMK_EVENT_RAISE(ev);                                                                           \
     return 0;
 
+u8_t zmk_layer_default() { return zmk_keymap_layer_default; }
+
+u32_t zmk_layer_state() { return zmk_keymap_layer_state; }
+
 bool zmk_keymap_layer_active(u8_t layer) {
     return (zmk_keymap_layer_state & (BIT(layer))) == (BIT(layer));
 };
 
+u8_t zmk_highest_layer_active() {
+    for (u8_t layer = 31; layer > 0; layer--) {
+        if (zmk_keymap_layer_active(layer)) {
+            return layer;
+        }
+    }
+    return zmk_layer_default();
+}
+
 int zmk_keymap_layer_activate(u8_t layer) { SET_LAYER_STATE(layer, true); };
 
 int zmk_keymap_layer_deactivate(u8_t layer) { SET_LAYER_STATE(layer, false); };