swaybar: show hidden bar on key event

Since wayland does not currently allow swaybar to create global
keybinds, this is handled within sway and sent to the bar using a custom
event, so as not to pollute existing events, called bar_state_update.

include/ipc.h

@@ -30,6 +30,9 @@ enum ipc_command_type {
 	IPC_EVENT_BINDING = ((1<<31) | 5),
 	IPC_EVENT_SHUTDOWN = ((1<<31) | 6),
 	IPC_EVENT_TICK = ((1<<31) | 7),
+
+	// sway-specific event types
+	IPC_EVENT_BAR_STATE_UPDATE = ((1<<31) | 20),
 };
 
 #endif

include/sway/config.h

@@ -191,6 +191,7 @@ struct bar_config {
 	 * In "show" mode, it will always be shown on top of the active workspace.
 	 */
 	char *hidden_state;
+	bool visible_by_modifier; // only relevant in "hide" mode
 	/**
 	 * Id name used to identify the bar through IPC.
 	 *

include/sway/ipc-server.h

@@ -15,6 +15,7 @@ void ipc_event_workspace(struct sway_workspace *old,
 		struct sway_workspace *new, const char *change);
 void ipc_event_window(struct sway_container *window, const char *change);
 void ipc_event_barconfig_update(struct bar_config *bar);
+void ipc_event_bar_state_update(struct bar_config *bar);
 void ipc_event_mode(const char *mode, bool pango);
 void ipc_event_shutdown(const char *reason);
 void ipc_event_binding(struct sway_binding *binding);

include/swaybar/config.h

@@ -32,6 +32,7 @@ struct swaybar_config {
 	char *sep_symbol;
 	char *mode;
 	char *hidden_state;
+	char *modifier;
 	bool strip_workspace_numbers;
 	bool binding_mode_indicator;
 	bool wrap_scroll;

sway/config/bar.c

@@ -16,6 +16,7 @@
 #include "stringop.h"
 #include "list.h"
 #include "log.h"
+#include "util.h"
 
 static void terminate_swaybar(pid_t pid) {
 	wlr_log(WLR_DEBUG, "Terminating swaybar %d", pid);
@@ -101,6 +102,7 @@ struct bar_config *default_bar_config(void) {
 	bar->binding_mode_indicator = true;
 	bar->verbose = false;
 	bar->pid = 0;
+	bar->modifier = get_modifier_mask_by_name("Mod4");
 	if (!(bar->mode = strdup("dock"))) {
 	       goto cleanup;
 	}

sway/input/keyboard.c

@@ -9,6 +9,7 @@
 #include "sway/input/input-manager.h"
 #include "sway/input/keyboard.h"
 #include "sway/input/seat.h"
+#include "sway/ipc-server.h"
 #include "log.h"
 
 /**
@@ -235,7 +236,6 @@ static void handle_keyboard_key(struct wl_listener *listener, void *data) {
 				code_modifiers);
 	}
 
-
 	bool handled = false;
 
 	// Identify active release binding
@@ -337,6 +337,19 @@ static int handle_keyboard_repeat(void *data) {
 	return 0;
 }
 
+static void determine_bar_visibility(uint32_t modifiers) {
+	for (int i = 0; i < config->bars->length; ++i) {
+		struct bar_config *bar = config->bars->items[i];
+		if (strcmp(bar->mode, bar->hidden_state) == 0) { // both are "hide"
+			bool should_be_visible = (~modifiers & bar->modifier) == 0;
+			if (bar->visible_by_modifier != should_be_visible) {
+				bar->visible_by_modifier = should_be_visible;
+				ipc_event_bar_state_update(bar);
+			}
+		}
+	}
+}
+
 static void handle_keyboard_modifiers(struct wl_listener *listener,
 		void *data) {
 	struct sway_keyboard *keyboard =
@@ -346,6 +359,9 @@ static void handle_keyboard_modifiers(struct wl_listener *listener,
 		keyboard->seat_device->input_device->wlr_device;
 	wlr_seat_set_keyboard(wlr_seat, wlr_device);
 	wlr_seat_keyboard_notify_modifiers(wlr_seat, &wlr_device->keyboard->modifiers);
+
+	uint32_t modifiers = wlr_keyboard_get_modifiers(wlr_device->keyboard);
+	determine_bar_visibility(modifiers);
 }
 
 struct sway_keyboard *sway_keyboard_create(struct sway_seat *seat,

sway/ipc-server.c

@@ -349,6 +349,22 @@ void ipc_event_barconfig_update(struct bar_config *bar) {
 	json_object_put(json);
 }
 
+void ipc_event_bar_state_update(struct bar_config *bar) {
+	if (!ipc_has_event_listeners(IPC_EVENT_BAR_STATE_UPDATE)) {
+		return;
+	}
+	wlr_log(WLR_DEBUG, "Sending bar_state_update event");
+
+	json_object *json = json_object_new_object();
+	json_object_object_add(json, "id", json_object_new_string(bar->id));
+	json_object_object_add(json, "visible_by_modifier",
+			json_object_new_boolean(bar->visible_by_modifier));
+
+	const char *json_string = json_object_to_json_string(json);
+	ipc_send_event(json_string, IPC_EVENT_BAR_STATE_UPDATE);
+	json_object_put(json);
+}
+
 void ipc_event_mode(const char *mode, bool pango) {
 	if (!ipc_has_event_listeners(IPC_EVENT_MODE)) {
 		return;
@@ -651,6 +667,8 @@ void ipc_client_handle_command(struct ipc_client *client) {
 				client->subscribed_events |= event_mask(IPC_EVENT_WORKSPACE);
 			} else if (strcmp(event_type, "barconfig_update") == 0) {
 				client->subscribed_events |= event_mask(IPC_EVENT_BARCONFIG_UPDATE);
+			} else if (strcmp(event_type, "bar_state_update") == 0) {
+				client->subscribed_events |= event_mask(IPC_EVENT_BAR_STATE_UPDATE);
 			} else if (strcmp(event_type, "mode") == 0) {
 				client->subscribed_events |= event_mask(IPC_EVENT_MODE);
 			} else if (strcmp(event_type, "shutdown") == 0) {

swaybar/ipc.c

@@ -367,7 +367,7 @@ bool ipc_initialize(struct swaybar *bar) {
 	struct swaybar_config *config = bar->config;
 	char subscribe[128]; // suitably large buffer
 	len = snprintf(subscribe, 128,
-			"[ \"barconfig_update\" %s %s ]",
+			"[ \"barconfig_update\" , \"bar_state_update\" %s %s ]",
 			config->binding_mode_indicator ? ", \"mode\"" : "",
 			config->workspace_buttons ? ", \"workspace\"" : "");
 	free(ipc_single_command(bar->ipc_event_socketfd,
@@ -375,6 +375,20 @@ bool ipc_initialize(struct swaybar *bar) {
 	return true;
 }
 
+static bool handle_bar_state_update(struct swaybar *bar, json_object *event) {
+	json_object *json_id;
+	json_object_object_get_ex(event, "id", &json_id);
+	const char *id = json_object_get_string(json_id);
+	if (strcmp(id, bar->id) != 0) {
+		return false;
+	}
+
+	json_object *visible_by_modifier;
+	json_object_object_get_ex(event, "visible_by_modifier", &visible_by_modifier);
+	bar->visible_by_modifier = json_object_get_boolean(visible_by_modifier);
+	return determine_bar_visibility(bar, false);
+}
+
 static bool handle_barconfig_update(struct swaybar *bar,
 		json_object *json_config) {
 	json_object *json_id;
@@ -444,6 +458,9 @@ bool handle_ipc_readable(struct swaybar *bar) {
 	case IPC_EVENT_BARCONFIG_UPDATE:
 		bar_is_dirty = handle_barconfig_update(bar, result);
 		break;
+	case IPC_EVENT_BAR_STATE_UPDATE:
+		bar_is_dirty = handle_bar_state_update(bar, result);
+		break;
 	default:
 		bar_is_dirty = false;
 		break;