Implement bindsym --release

This is a "simple" version of --release (same as i3) that only supports
a binding that contain one normal key. e.g.:

    bindsym --release $mod+x exec somthing-fun

I didn't bother implementing it for a combination like `$mod+x+z` since
it is a bit tricky to get right and also a bit weird to actually do on a
keyboard.

include/config.h

@@ -22,6 +22,7 @@ struct sway_variable {
  */
 struct sway_binding {
 	int order;
+	bool release;
 	list_t *keys;
 	uint32_t modifiers;
 	char *command;

include/input_state.h

@@ -9,6 +9,9 @@
 // returns true if key has been pressed, otherwise false
 bool check_key(uint32_t key_sym, uint32_t key_code);
 
+// returns true if key_sym matches latest released key.
+bool check_released_key(uint32_t key_sym);
+
 // sets a key as pressed
 void press_key(uint32_t key_sym, uint32_t key_code);
 

sway/commands.c

@@ -163,9 +163,25 @@ static struct cmd_results *cmd_bindsym(int argc, char **argv) {
 		return cmd_results_new(CMD_FAILURE, "bindsym", "Can only be used in config file.");
 	}
 
+
 	struct sway_binding *binding = malloc(sizeof(struct sway_binding));
 	binding->keys = create_list();
 	binding->modifiers = 0;
+	binding->release = false;
+
+	// Handle --release
+	if (strcmp("--release", argv[0]) == 0) {
+		if (argc >= 3) {
+			binding->release = true;
+			argv++;
+			argc--;
+		} else {
+			return cmd_results_new(CMD_FAILURE, "bindsym",
+				"Invalid bindsym command"
+				"(expected more than 2 arguments, got %d)", argc);
+		}
+	}
+
 	binding->command = join_args(argv + 1, argc - 1);
 
 	list_t *split = split_string(argv[0], "+");

sway/handlers.c

@@ -336,6 +336,43 @@ static void handle_view_state_request(wlc_handle view, enum wlc_view_state_bit s
 	return;
 }
 
+static bool handle_bindsym(struct sway_binding *binding) {
+	bool match = false;
+	int i;
+	for (i = 0; i < binding->keys->length; ++i) {
+		xkb_keysym_t *key = binding->keys->items[i];
+		if ((match = check_key(*key, 0)) == false) {
+			break;
+		}
+	}
+
+	if (match) {
+		struct cmd_results *res = handle_command(binding->command);
+		if (res->status != CMD_SUCCESS) {
+			sway_log(L_ERROR, "Command '%s' failed: %s", res->input, res->error);
+		}
+		free_cmd_results(res);
+		return true;
+	}
+
+	return false;
+}
+
+static bool handle_bindsym_release(struct sway_binding *binding) {
+	if (binding->keys->length == 1) {
+		xkb_keysym_t *key = binding->keys->items[0];
+		if (check_released_key(*key)) {
+			struct cmd_results *res = handle_command(binding->command);
+			if (res->status != CMD_SUCCESS) {
+				sway_log(L_ERROR, "Command '%s' failed: %s", res->input, res->error);
+			}
+			free_cmd_results(res);
+			return true;
+		}
+	}
+
+	return false;
+}
 
 static bool handle_key(wlc_handle view, uint32_t time, const struct wlc_modifiers *modifiers,
 		uint32_t key, enum wlc_key_state state) {
@@ -366,33 +403,6 @@ static bool handle_key(wlc_handle view, uint32_t time, const struct wlc_modifier
 		release_key(sym, key);
 	}
 
-	for (i = 0; i < mode->bindings->length; ++i) {
-		struct sway_binding *binding = mode->bindings->items[i];
-
-		if ((modifiers->mods ^ binding->modifiers) == 0) {
-			bool match = false;
-			int j;
-			for (j = 0; j < binding->keys->length; ++j) {
-				xkb_keysym_t *key = binding->keys->items[j];
-				if ((match = check_key(*key, 0)) == false) {
-					break;
-				}
-			}
-			if (match) {
-				if (state == WLC_KEY_STATE_PRESSED) {
-					struct cmd_results *res = handle_command(binding->command);
-					if (res->status != CMD_SUCCESS) {
-						sway_log(L_ERROR, "Command '%s' failed: %s", res->input, res->error);
-					}
-					free_cmd_results(res);
-					return EVENT_HANDLED;
-				} else if (state == WLC_KEY_STATE_RELEASED) {
-					// TODO: --released
-				}
-			}
-		}
-	}
-
 	// handle bar modifiers pressed/released
 	uint32_t modifier;
 	for (i = 0; i < config->active_bar_modifiers->length; ++i) {
@@ -409,6 +419,27 @@ static bool handle_key(wlc_handle view, uint32_t time, const struct wlc_modifier
 	}
 	// update modifiers state
 	modifiers_state_update(modifiers->mods);
+
+	// handle bindings
+	for (i = 0; i < mode->bindings->length; ++i) {
+		struct sway_binding *binding = mode->bindings->items[i];
+		if ((modifiers->mods ^ binding->modifiers) == 0) {
+			switch (state) {
+			case WLC_KEY_STATE_PRESSED: {
+				if (!binding->release && handle_bindsym(binding)) {
+					return EVENT_HANDLED;
+				}
+				break;
+			}
+			case WLC_KEY_STATE_RELEASED:
+				if (binding->release && handle_bindsym_release(binding)) {
+					return EVENT_HANDLED;
+				}
+				break;
+			}
+		}
+	}
+
 	return EVENT_PASSTHROUGH;
 }
 

sway/input_state.c

@@ -22,6 +22,8 @@ struct key_state {
 
 static struct key_state key_state_array[KEY_STATE_MAX_LENGTH];
 
+static struct key_state last_released;
+
 static uint32_t modifiers_state;
 
 void input_init(void) {
@@ -31,6 +33,9 @@ void input_init(void) {
 		key_state_array[i] = none;
 	}
 
+	struct key_state none = { 0, 0, 0 };
+	last_released = none;
+
 	modifiers_state = 0;
 }
 
@@ -76,6 +81,12 @@ bool check_key(uint32_t key_sym, uint32_t key_code) {
 	return find_key(key_sym, key_code, false) < KEY_STATE_MAX_LENGTH;
 }
 
+bool check_released_key(uint32_t key_sym) {
+	return (key_sym != 0
+		&& (last_released.key_sym == key_sym
+		|| last_released.alt_sym == key_sym));
+}
+
 void press_key(uint32_t key_sym, uint32_t key_code) {
 	if (key_code == 0) {
 		return;
@@ -94,6 +105,9 @@ void press_key(uint32_t key_sym, uint32_t key_code) {
 void release_key(uint32_t key_sym, uint32_t key_code) {
 	uint8_t index = find_key(key_sym, key_code, true);
 	if (index < KEY_STATE_MAX_LENGTH) {
+		last_released.key_sym = key_state_array[index].key_sym;
+		last_released.alt_sym = key_state_array[index].alt_sym;
+		last_released.key_code = key_state_array[index].key_code;
 		struct key_state none = { 0, 0, 0 };
 		key_state_array[index] = none;
 	}