feat(combos): add layer filtering

app/Kconfig

@@ -301,6 +301,10 @@ config ZMK_COMBO_MAX_KEYS_PER_COMBO
 	int "Maximum number of keys per combo"
 	default 4
 
+config ZMK_COMBO_MAX_LAYER_FILTERS_PER_COMBO
+	int "Maximum number of layers that can be specified per combo"
+	default 4
+
 #Display/LED Options
 endmenu
 

app/dts/bindings/zmk,combos.yaml

@@ -20,3 +20,6 @@ child-binding:
       default: 50
     slow-release:
       type: boolean
+    layers:
+      type: array
+      default: [-1]

app/src/combo.c

@@ -17,6 +17,7 @@
 #include <zmk/events/position_state_changed.h>
 #include <zmk/hid.h>
 #include <zmk/matrix.h>
+#include <zmk/keymap.h>
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
@@ -33,6 +34,8 @@ struct combo_cfg {
     // the virtual key position is a key position outside the range used by the keyboard.
     // it is necessary so hold-taps can uniquely identify a behavior.
     int32_t virtual_key_position;
+    int8_t layers[CONFIG_ZMK_COMBO_MAX_LAYER_FILTERS_PER_COMBO];
+    int32_t layers_len;
 };
 
 struct active_combo {
@@ -104,17 +107,35 @@ static int initialize_combo(struct combo_cfg *new_combo) {
     return 0;
 }
 
+static bool combo_active_on_layer(struct combo_cfg *combo, uint8_t layer) {
+    if (combo->layers[0] == -1) {
+        // -1 in the first layer position is global layer scope
+        return true;
+    }
+    for (int j = 0; j < combo->layers_len; j++) {
+        if (combo->layers[j] == layer) {
+            return true;
+        }
+    }
+    return false;
+}
+
 static int setup_candidates_for_first_keypress(int32_t position, int64_t timestamp) {
+    int number_of_combo_candidates = 0;
+    uint8_t highest_active_layer = zmk_keymap_highest_layer_active();
     for (int i = 0; i < CONFIG_ZMK_COMBO_MAX_COMBOS_PER_KEY; i++) {
         struct combo_cfg *combo = combo_lookup[position][i];
         if (combo == NULL) {
-            return i;
+            return number_of_combo_candidates;
+        }
+        if (combo_active_on_layer(combo, highest_active_layer)) {
+            candidates[number_of_combo_candidates].combo = combo;
+            candidates[number_of_combo_candidates].timeout_at = timestamp + combo->timeout_ms;
+            number_of_combo_candidates++;
         }
-        candidates[i].combo = combo;
-        candidates[i].timeout_at = timestamp + combo->timeout_ms;
         // LOG_DBG("combo timeout %d %d %d", position, i, candidates[i].timeout_at);
     }
-    return CONFIG_ZMK_COMBO_MAX_COMBOS_PER_KEY;
+    return number_of_combo_candidates;
 }
 
 static int filter_candidates(int32_t position) {
@@ -451,6 +472,8 @@ ZMK_SUBSCRIPTION(combo, zmk_position_state_changed);
         .behavior = KEY_BINDING_TO_STRUCT(0, n),                                                   \
         .virtual_key_position = ZMK_KEYMAP_LEN + __COUNTER__,                                      \
         .slow_release = DT_PROP(n, slow_release),                                                  \
+        .layers = DT_PROP(n, layers),                                                              \
+        .layers_len = DT_PROP_LEN(n, layers),                                                      \
     };
 
 #define INITIALIZE_COMBO(n) initialize_combo(&combo_config_##n);

app/tests/combo/layer-filter-0/events.patterns

@@ -0,0 +1,2 @@
+s/.*hid_listener_keycode_//p
+s/.*combo//p

app/tests/combo/layer-filter-0/keycode_events.snapshot

@@ -0,0 +1,8 @@
+pressed: usage_page 0x07 keycode 0x1b implicit_mods 0x00 explicit_mods 0x00
+released: usage_page 0x07 keycode 0x1b implicit_mods 0x00 explicit_mods 0x00
+pressed: usage_page 0x07 keycode 0x04 implicit_mods 0x00 explicit_mods 0x00
+released: usage_page 0x07 keycode 0x04 implicit_mods 0x00 explicit_mods 0x00
+pressed: usage_page 0x07 keycode 0x1c implicit_mods 0x00 explicit_mods 0x00
+released: usage_page 0x07 keycode 0x1c implicit_mods 0x00 explicit_mods 0x00
+pressed: usage_page 0x07 keycode 0x04 implicit_mods 0x00 explicit_mods 0x00
+released: usage_page 0x07 keycode 0x04 implicit_mods 0x00 explicit_mods 0x00

app/tests/combo/layer-filter-0/native_posix.keymap

@@ -0,0 +1,78 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+
+/* it is useful to set timeout to a large value when attaching a debugger. */
+#define TIMEOUT (60*60*1000)
+
+/ {
+	combos {
+		compatible = "zmk,combos";
+		combo_one {
+			timeout-ms = <TIMEOUT>;
+			key-positions = <0 1>;
+			bindings = <&kp X>;
+			layers = <0>;
+		};
+
+		combo_two {
+			timeout-ms = <TIMEOUT>;
+			key-positions = <0 1>;
+			bindings = <&kp Y>;
+			layers = <1>;
+		};
+
+		combo_three {
+			timeout-ms = <TIMEOUT>;
+			key-positions = <0 2>;
+			bindings = <&kp Z>;
+		};
+	};
+
+	keymap {
+		compatible = "zmk,keymap";
+		label ="Default keymap";
+
+		default_layer {
+			bindings = <
+				&kp A &kp B
+				&kp C &tog 1
+			>;
+		};
+
+		filtered_layer {
+			bindings = <
+				&kp A &kp B
+				&kp C &tog 0
+			>;
+		};
+	};
+};
+
+&kscan {
+	events = <
+		/* Combo One */
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(0,1,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(0,1,10)
+		/* Combo Three */
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(1,1,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(1,1,10)
+		/* Toggle Layer */
+		ZMK_MOCK_PRESS(1,1,10) 
+		ZMK_MOCK_RELEASE(1,1,10)
+		/* Combo Two */
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(0,1,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(0,1,10)
+		/* Combo Three */
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(1,1,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(1,1,10)
+	>;
+};

app/tests/combo/layer-filter-1/events.patterns

@@ -0,0 +1,2 @@
+s/.*hid_listener_keycode_//p
+s/.*combo//p

app/tests/combo/layer-filter-1/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x04 implicit_mods 0x00 explicit_mods 0x00
+pressed: usage_page 0x07 keycode 0x05 implicit_mods 0x00 explicit_mods 0x00
+released: usage_page 0x07 keycode 0x04 implicit_mods 0x00 explicit_mods 0x00
+released: usage_page 0x07 keycode 0x05 implicit_mods 0x00 explicit_mods 0x00

app/tests/combo/layer-filter-1/native_posix.keymap

@@ -0,0 +1,40 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+
+/* it is useful to set timeout to a large value when attaching a debugger. */
+#define TIMEOUT (60*60*1000)
+
+/ {
+	combos {
+		compatible = "zmk,combos";
+		combo_one {
+			timeout-ms = <TIMEOUT>;
+			key-positions = <0 1>;
+			bindings = <&kp X>;
+			layers = <1>;
+		};
+	};
+
+	keymap {
+		compatible = "zmk,keymap";
+		label ="Default keymap";
+
+		default_layer {
+			bindings = <
+				&kp A &kp B
+				&kp C &tog 1
+			>;
+		};
+	};
+};
+
+&kscan {
+	events = <
+		/* Combo One */
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(0,1,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(0,1,10)
+	>;
+};

docs/docs/features/combos.md

@@ -18,6 +18,7 @@ Combos configured in your `.keymap` file, but are separate from the `keymap` nod
 			timeout-ms = <50>;
 			key-positions = <0 1>;
 			bindings = <&kp ESC>;
+			layers = <-1>;
 		};
 	};
 };
@@ -27,6 +28,7 @@ Combos configured in your `.keymap` file, but are separate from the `keymap` nod
 - The `compatible` property should always be `"zmk,combos"` for combos.
 - `timeout-ms` is the number of milliseconds that all keys of the combo must be pressed.
 - `key-positions` is an array of key positions. See the info section below about how to figure out the positions on your board.
+- `layers = <0 1...>` will allow limiting a combo to specific layers. this is an _optional_ parameter and defaults to `-1` which is global scope.
 - `bindings` is the behavior that is activated when the behavior is pressed.
 - (advanced) you can specify `slow-release` if you want the combo binding to be released when all key-positions are released. The default is to release the combo as soon as any of the keys in the combo is released.
 
@@ -49,3 +51,4 @@ There are three global combo parameters which are set through KConfig. You can s
 - `CONFIG_ZMK_COMBO_MAX_PRESSED_COMBOS` is the number of combos that can be active at the same time. Default 4.
 - `CONFIG_ZMK_COMBO_MAX_COMBOS_PER_KEY` is the maximum number of combos that can be active on a key position. Defaults to 5. (So you can have 5 separate combos that use position `3` for example)
 - `CONFIG_ZMK_COMBO_MAX_KEYS_PER_COMBO` is the maximum number of keys that need to be pressed to activate a combo. Default 4. If you want a combo that triggers when pressing 5 keys, you'd set this to 5 for example.
+- `ZMK_COMBO_MAX_LAYER_FILTERS_PER_COMBO` is the maximum number of layer filters that can be specified. Default 4. If you want use layer filters with a combo that spans more than 4 layers, you'll need to change this value.