input: reconfigure send_events on output hotplug

Closes: https://github.com/swaywm/sway/issues/7890

include/sway/input/libinput.h

@@ -4,6 +4,9 @@
 
 bool sway_input_configure_libinput_device(struct sway_input_device *device);
 
+void sway_input_configure_libinput_device_send_events(
+	struct sway_input_device *device);
+
 void sway_input_reset_libinput_device(struct sway_input_device *device);
 
 bool sway_libinput_device_is_builtin(struct sway_input_device *device);

sway/input/input-manager.c

@@ -534,6 +534,13 @@ void input_manager_configure_all_input_mappings(void) {
 		wl_list_for_each(seat, &server.input->seats, link) {
 			seat_configure_device_mapping(seat, input_device);
 		}
+
+#if WLR_HAS_LIBINPUT_BACKEND
+		// Input devices mapped to unavailable outputs get their libinput
+		// send_events setting switched to false. We need to re-enable this
+		// when the output appears.
+		sway_input_configure_libinput_device_send_events(input_device);
+#endif
 	}
 }
 

sway/input/libinput.c

@@ -219,36 +219,38 @@ static bool set_calibration_matrix(struct libinput_device *dev, float mat[6]) {
 	return changed;
 }
 
-bool sway_input_configure_libinput_device(struct sway_input_device *input_device) {
-	struct input_config *ic = input_device_get_config(input_device);
-	if (!ic || !wlr_input_device_is_libinput(input_device->wlr_device)) {
-		return false;
-	}
-
-	struct libinput_device *device =
-		wlr_libinput_get_device_handle(input_device->wlr_device);
-	sway_log(SWAY_DEBUG, "sway_input_configure_libinput_device('%s' on '%s')",
-			ic->identifier, input_device->identifier);
-
-	bool changed = false;
+static bool configure_send_events(struct libinput_device *device,
+		struct input_config *ic) {
 	if (ic->mapped_to_output &&
 			strcmp("*", ic->mapped_to_output) != 0 &&
 			!output_by_name_or_id(ic->mapped_to_output)) {
 		sway_log(SWAY_DEBUG,
 				"%s '%s' is mapped to offline output '%s'; disabling input",
 				ic->input_type, ic->identifier, ic->mapped_to_output);
-		changed |= set_send_events(device,
-			LIBINPUT_CONFIG_SEND_EVENTS_DISABLED);
+		return set_send_events(device, LIBINPUT_CONFIG_SEND_EVENTS_DISABLED);
 	} else if (ic->send_events != INT_MIN) {
-		changed |= set_send_events(device, ic->send_events);
+		return set_send_events(device, ic->send_events);
 	} else {
 		// Have to reset to the default mode here, otherwise if ic->send_events
 		// is unset and a mapped output just came online after being disabled,
 		// we'd remain stuck sending no events.
-		changed |= set_send_events(device,
+		return set_send_events(device,
 			libinput_device_config_send_events_get_default_mode(device));
 	}
+}
 
+bool sway_input_configure_libinput_device(struct sway_input_device *input_device) {
+	struct input_config *ic = input_device_get_config(input_device);
+	if (!ic || !wlr_input_device_is_libinput(input_device->wlr_device)) {
+		return false;
+	}
+
+	struct libinput_device *device =
+		wlr_libinput_get_device_handle(input_device->wlr_device);
+	sway_log(SWAY_DEBUG, "sway_input_configure_libinput_device('%s' on '%s')",
+			ic->identifier, input_device->identifier);
+
+	bool changed = configure_send_events(device, ic);
 	if (ic->tap != INT_MIN) {
 		changed |= set_tap(device, ic->tap);
 	}
@@ -304,6 +306,22 @@ bool sway_input_configure_libinput_device(struct sway_input_device *input_device
 	return changed;
 }
 
+void sway_input_configure_libinput_device_send_events(
+		struct sway_input_device *input_device) {
+	struct input_config *ic = input_device_get_config(input_device);
+	if (!ic || !wlr_input_device_is_libinput(input_device->wlr_device)) {
+		return;
+	}
+
+	struct libinput_device *device =
+		wlr_libinput_get_device_handle(input_device->wlr_device);
+	bool changed = configure_send_events(device, ic);
+
+	if (changed) {
+		ipc_event_input("libinput_config", input_device);
+	}
+}
+
 void sway_input_reset_libinput_device(struct sway_input_device *input_device) {
 	if (!wlr_input_device_is_libinput(input_device->wlr_device)) {
 		return;