Feature: Layer toggle

app/CMakeLists.txt

@@ -38,6 +38,7 @@ target_sources(app PRIVATE src/behaviors/behavior_key_press.c)
 target_sources(app PRIVATE src/behaviors/behavior_reset.c)
 target_sources(app PRIVATE src/behaviors/behavior_mod_tap.c)
 target_sources(app PRIVATE src/behaviors/behavior_momentary_layer.c)
+target_sources(app PRIVATE src/behaviors/behavior_toggle_layer.c)
 target_sources(app PRIVATE src/behaviors/behavior_transparent.c)
 target_sources(app PRIVATE src/behaviors/behavior_sensor_rotate_key_press.c)
 target_sources_ifdef(CONFIG_ZMK_RGB_UNDERGLOW app PRIVATE src/behaviors/behavior_rgb_underglow.c)

app/dts/behaviors.dtsi

@@ -2,6 +2,7 @@
 #include <behaviors/transparent.dtsi>
 #include <behaviors/mod_tap.dtsi>
 #include <behaviors/momentary_layer.dtsi>
+#include <behaviors/toggle_layer.dtsi>
 #include <behaviors/reset.dtsi>
 #include <behaviors/sensor_rotate_key_press.dtsi>
 #include <behaviors/rgb_underglow.dtsi>

app/dts/behaviors/toggle_layer.dtsi

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2020 Cody McGinnis <brainwart@gmail.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+ / {
+	behaviors {
+		tog: behavior_toggle_layer {
+			compatible = "zmk,behavior-toggle-layer";
+			label = "TOGGLE_LAYER";
+			#binding-cells = <1>;
+		};
+	};
+};

app/dts/bindings/behaviors/zmk,behavior-toggle-layer.yaml

@@ -0,0 +1,8 @@
+# Copyright (c) 2020, Cody McGinnis <brainwart@gmail.com>
+# SPDX-License-Identifier: MIT
+
+description: Toggle Layer
+
+compatible: "zmk,behavior-toggle-layer"
+
+include: one_param.yaml

app/include/zmk/keymap.h

@@ -1,6 +1,8 @@
 #pragma once
 
+bool zmk_keymap_layer_active(u8_t layer);
 int zmk_keymap_layer_activate(u8_t layer);
 int zmk_keymap_layer_deactivate(u8_t layer);
+int zmk_keymap_layer_toggle(u8_t layer);
 
 int zmk_keymap_position_state_changed(u32_t position, bool pressed);

app/src/behaviors/behavior_toggle_layer.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2020 Cody McGinnis <brainwart@gmail.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#define DT_DRV_COMPAT zmk_behavior_toggle_layer
+
+#include <device.h>
+#include <drivers/behavior.h>
+#include <logging/log.h>
+
+#include <zmk/keymap.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+struct behavior_tog_config { };
+struct behavior_tog_data { };
+
+static int behavior_tog_init(struct device *dev)
+{
+	return 0;
+};
+
+
+static int tog_keymap_binding_pressed(struct device *dev, u32_t position, u32_t layer, u32_t _)
+{
+  return zmk_keymap_layer_toggle(layer);
+}
+
+static int tog_keymap_binding_released(struct device *dev, u32_t position, u32_t layer, u32_t _)
+{
+  return 0;
+}
+
+static const struct behavior_driver_api behavior_tog_driver_api = {
+  .binding_pressed = tog_keymap_binding_pressed,
+  .binding_released = tog_keymap_binding_released,
+};
+
+static const struct behavior_tog_config behavior_tog_config = {};
+
+static struct behavior_tog_data behavior_tog_data;
+
+DEVICE_AND_API_INIT(behavior_tog, DT_INST_LABEL(0), behavior_tog_init,
+                    &behavior_tog_data,
+                    &behavior_tog_config,
+                    APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
+                    &behavior_tog_driver_api);

app/src/keymap.c

@@ -76,6 +76,11 @@ static struct zmk_behavior_binding zmk_sensor_keymap[ZMK_KEYMAP_LAYERS_LEN][ZMK_
 	WRITE_BIT(zmk_keymap_layer_state, layer, state); \
 	return 0;
 
+bool zmk_keymap_layer_active(u8_t layer)
+{
+	return (zmk_keymap_layer_state & (BIT(layer))) == (BIT(layer));
+};
+
 int zmk_keymap_layer_activate(u8_t layer)
 {
 	SET_LAYER_STATE(layer, true);
@@ -86,6 +91,16 @@ int zmk_keymap_layer_deactivate(u8_t layer)
 	SET_LAYER_STATE(layer, false);
 };
 
+int zmk_keymap_layer_toggle(u8_t layer)
+{
+	if (zmk_keymap_layer_active(layer))
+	{
+		return zmk_keymap_layer_deactivate(layer);
+	}
+
+  	return zmk_keymap_layer_activate(layer);
+};
+
 bool is_active_position(u32_t position, u8_t layer)
 {
 	return (zmk_keymap_layer_state & BIT(layer)) == BIT(layer)

docs/docs/behavior/layers.md

@@ -39,3 +39,54 @@ Example:
 ```
 &mo LOWER
 ```
+
+## Toggle Layer
+
+The "toggle layer" behavior allows you to enable a layer until the layer is manually disabled.
+
+### Behavior Binding
+
+- Reference: `&tog`
+- Parameter: The layer number to enable/disable, e.g. `1`
+
+Example:
+
+```
+&tog LOWER
+```
+
+"Toggle layer" for a :
+```
+#define DEFAULT 0
+#define NAVI    1
+
+#define NONE 0
+
+/ {
+	keymap {
+		compatible = "zmk,keymap";
+
+		default_layer {
+			bindings = <
+                &tog NAVI &kp KDIV  &kp KMLT  &kp KMIN
+                &kp NUM_7 &kp NUM_8 &kp NUM_9 &kp KPLS
+                &kp NUM_4 &kp NUM_5 &kp NUM_6 &kp KPLS
+                &kp NUM_1 &kp NUM_2 &kp NUM_3 &kp RET
+                &kp NUM_0 &kp NUM_0 &kp DOT   &kp RET
+			>;
+		};
+
+		nav_layer {
+			bindings = <
+                &tog NAVI &kp KDIV  &kp KMLT  &kp KMIN
+                &kp HOME  &kp UARW  &kp PGUP  &kp KPLS
+                &kp LARW  &none     &kp RARW  &kp KPLS
+                &kp END   &kp DARW  &kp PGDN  &kp RET
+                &kp INS   &kp INS   &kp DEL   &kp RET
+            >;
+		};
+	};
+};
+```
+
+It is possible to use "toggle layer" to have keys that raise and lower the layers as well.