ipc: add an input event

This adds an ipc event related to input devices. Currently the
following changes are supported:
- added: when an input device becomes available
- removed: when an input device is no longer available
- xkb_keymap_changed: (keyboards only) the keymap changed
- xkb_layout_changed: (keyboards only) the effective layout changed

include/ipc.h

@@ -34,6 +34,7 @@ enum ipc_command_type {
 
 	// sway-specific event types
 	IPC_EVENT_BAR_STATE_UPDATE = ((1<<31) | 20),
+	IPC_EVENT_INPUT = ((1<<31) | 21),
 };
 
 #endif

include/sway/input/keyboard.h

@@ -52,6 +52,7 @@ struct sway_keyboard {
 	struct sway_seat_device *seat_device;
 
 	struct xkb_keymap *keymap;
+	xkb_layout_index_t effective_layout;
 
 	struct wl_listener keyboard_key;
 	struct wl_listener keyboard_modifiers;

include/sway/ipc-server.h

@@ -2,6 +2,7 @@
 #define _SWAY_IPC_SERVER_H
 #include <sys/socket.h>
 #include "sway/config.h"
+#include "sway/input/input-manager.h"
 #include "sway/tree/container.h"
 #include "ipc.h"
 
@@ -19,5 +20,6 @@ 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);
+void ipc_event_input(const char *change, struct sway_input_device *device);
 
 #endif

sway/input/input-manager.c

@@ -12,6 +12,7 @@
 #include "sway/config.h"
 #include "sway/input/input-manager.h"
 #include "sway/input/seat.h"
+#include "sway/ipc-server.h"
 #include "sway/server.h"
 #include "stringop.h"
 #include "list.h"
@@ -584,6 +585,8 @@ static void handle_device_destroy(struct wl_listener *listener, void *data) {
 		seat_remove_device(seat, input_device);
 	}
 
+	ipc_event_input("removed", input_device);
+
 	wl_list_remove(&input_device->link);
 	wl_list_remove(&input_device->device_destroy.link);
 	free(input_device->identifier);
@@ -656,6 +659,8 @@ static void handle_new_input(struct wl_listener *listener, void *data) {
 			"device '%s' is not configured on any seats",
 			input_device->identifier);
 	}
+
+	ipc_event_input("added", input_device);
 }
 
 static void handle_inhibit_activate(struct wl_listener *listener, void *data) {

sway/input/keyboard.c

@@ -473,6 +473,11 @@ static void handle_keyboard_modifiers(struct wl_listener *listener,
 
 	uint32_t modifiers = wlr_keyboard_get_modifiers(wlr_device->keyboard);
 	determine_bar_visibility(modifiers);
+
+	if (wlr_device->keyboard->modifiers.group != keyboard->effective_layout) {
+		keyboard->effective_layout = wlr_device->keyboard->modifiers.group;
+		ipc_event_input("xkb_layout", keyboard->seat_device->input_device);
+	}
 }
 
 struct sway_keyboard *sway_keyboard_create(struct sway_seat *seat,
@@ -603,8 +608,23 @@ void sway_keyboard_configure(struct sway_keyboard *keyboard) {
 		}
 	}
 
+	bool keymap_changed = false;
+	bool effective_layout_changed = keyboard->effective_layout != 0;
+	if (keyboard->keymap) {
+		char *old_keymap_string = xkb_keymap_get_as_string(keyboard->keymap,
+			XKB_KEYMAP_FORMAT_TEXT_V1);
+		char *new_keymap_string = xkb_keymap_get_as_string(keymap,
+			XKB_KEYMAP_FORMAT_TEXT_V1);
+		keymap_changed = strcmp(old_keymap_string, new_keymap_string);
+		free(old_keymap_string);
+		free(new_keymap_string);
+	} else {
+		keymap_changed = true;
+	}
+
 	xkb_keymap_unref(keyboard->keymap);
 	keyboard->keymap = keymap;
+	keyboard->effective_layout = 0;
 	wlr_keyboard_set_keymap(wlr_device->keyboard, keyboard->keymap);
 
 	xkb_mod_mask_t locked_mods = 0;
@@ -654,6 +674,14 @@ void sway_keyboard_configure(struct sway_keyboard *keyboard) {
 	wl_signal_add(&wlr_device->keyboard->events.modifiers,
 		&keyboard->keyboard_modifiers);
 	keyboard->keyboard_modifiers.notify = handle_keyboard_modifiers;
+
+	if (keymap_changed) {
+		ipc_event_input("xkb_keymap",
+			keyboard->seat_device->input_device);
+	} else if (effective_layout_changed) {
+		ipc_event_input("xkb_layout",
+			keyboard->seat_device->input_device);
+	}
 }
 
 void sway_keyboard_destroy(struct sway_keyboard *keyboard) {

sway/ipc-server.c

@@ -487,6 +487,21 @@ static void ipc_event_tick(const char *payload) {
 	json_object_put(json);
 }
 
+void ipc_event_input(const char *change, struct sway_input_device *device) {
+	if (!ipc_has_event_listeners(IPC_EVENT_INPUT)) {
+		return;
+	}
+	sway_log(SWAY_DEBUG, "Sending input event");
+
+	json_object *json = json_object_new_object();
+	json_object_object_add(json, "change", json_object_new_string(change));
+	json_object_object_add(json, "input", ipc_json_describe_input(device));
+
+	const char *json_string = json_object_to_json_string(json);
+	ipc_send_event(json_string, IPC_EVENT_INPUT);
+	json_object_put(json);
+}
+
 int ipc_client_handle_writable(int client_fd, uint32_t mask, void *data) {
 	struct ipc_client *client = data;
 
@@ -716,6 +731,8 @@ void ipc_client_handle_command(struct ipc_client *client, uint32_t payload_lengt
 			} else if (strcmp(event_type, "tick") == 0) {
 				client->subscribed_events |= event_mask(IPC_EVENT_TICK);
 				is_tick = true;
+			} else if (strcmp(event_type, "input") == 0) {
+				client->subscribed_events |= event_mask(IPC_EVENT_INPUT);
 			} else {
 				const char msg[] = "{\"success\": false}";
 				ipc_send_reply(client, payload_type, msg, strlen(msg));

sway/sway-ipc.7.scd

@@ -1371,6 +1371,9 @@ available:
 |- 0x80000014
 :  bar_status_update
 :  Send when the visibility of a bar should change due to a modifier
+|- 0x80000015
+:  input
+:  Sent when something related to input devices changes
 
 
 ## 0x80000000. WORKSPACE
@@ -1702,6 +1705,56 @@ event is a single object with the following properties:
 }
 ```
 
+## 0x80000015. INPUT
+
+Sent when something related to the input devices changes. The event is a single
+object with the following properties:
+
+[- *PROPERTY*
+:- *DATA TYPE*
+:- *DESCRIPTION*
+|- change
+:  string
+:[ What has changed
+|- input
+:  object
+:  An object representing the input that is identical the ones GET_INPUTS gives
+
+The following change types are currently available:
+[- *TYPE*
+:- *DESCRIPTION*
+|- added
+:[ The input device became available
+|- removed
+:  The input device is no longer available
+|- xkb_keymap
+:  (Keyboards only) The keymap for the keyboard has changed
+|- xkb_layout
+:  (Keyboards only) The effective layout in the keymap has changed
+
+*Example Event:*
+```
+{
+	"change": "xkb_layout",
+	"input": {
+		"identifier": "1:1:AT_Translated_Set_2_keyboard",
+		"name": "AT Translated Set 2 keyboard",
+		"vendor": 1,
+		"product": 1,
+		"type": "keyboard",
+		"xkb_layout_names": [
+			"English (US)",
+			"English (Dvorak)"
+		],
+		"xkb_active_layout_index": 1,
+		"xkb_active_layout_name": "English (Dvorak)",
+		"libinput": {
+			"send_events": "enabled"
+		}
+	}
+}
+```
+
 # SEE ALSO
 
 *sway*(1) *sway*(5) *sway-bar*(5) *swaymsg*(1) *sway-input*(5) *sway-output*(5)