seat: only pass on sent keys on surface-focus

Key events associated with keybindings (both pressed and released) are not
sent to clients. When using wlr_seat_keyboard_notify_enter() it it
therefore important not to send the keycodes of _all_ pressed keys, but
only those that were actually _sent_ to clients (that is, those that were
not bound).

This approach is consistent with sway's implementation in input/seat.c
cffb006feb/sway/input/seat.c (L173-L175)

Fixes issue #510

include/key-state.h

@@ -2,6 +2,20 @@
 #ifndef __LABWC_KEY_STATE_H
 #define __LABWC_KEY_STATE_H
 
+/*
+ * All keycodes in these functions are (Linux) libinput evdev scancodes which is
+ * what 'wlr_keyboard' uses (e.g. 'seat->keyboard_group->keyboard->keycodes').
+ * Note: These keycodes are different to XKB scancodes by a value of 8.
+ */
+
+/**
+ * key_state_pressed_sent_keycodes - generate array of pressed+sent keys
+ * Note: The array is generated by subtracting any bound keys from _all_ pressed
+ * keys (because bound keys were not forwarded to clients).
+ */
+uint32_t *key_state_pressed_sent_keycodes(void);
+int key_state_nr_pressed_sent_keycodes(void);
+
 void key_state_set_pressed(uint32_t keycode, bool ispressed);
 void key_state_store_pressed_keys_as_bound(void);
 bool key_state_corresponding_press_event_was_bound(uint32_t keycode);

src/key-state.c

@@ -10,7 +10,7 @@ struct key_array {
 	int nr_keys;
 };
 
-static struct key_array pressed, bound;
+static struct key_array pressed, bound, pressed_sent;
 
 static void
 remove_key(struct key_array *array, uint32_t keycode)
@@ -35,6 +35,25 @@ add_key(struct key_array *array, uint32_t keycode)
 	array->keys[array->nr_keys++] = keycode;
 }
 
+uint32_t *
+key_state_pressed_sent_keycodes(void)
+{
+	/* pressed_sent = pressed - bound */
+	memcpy(pressed_sent.keys, pressed.keys,
+		MAX_PRESSED_KEYS * sizeof(uint32_t));
+	pressed_sent.nr_keys = pressed.nr_keys;
+	for (int i = 0; i < bound.nr_keys; ++i) {
+		remove_key(&pressed_sent, bound.keys[i]);
+	}
+	return pressed_sent.keys;
+}
+
+int
+key_state_nr_pressed_sent_keycodes(void)
+{
+	return pressed_sent.nr_keys;
+}
+
 void
 key_state_set_pressed(uint32_t keycode, bool ispressed)
 {

src/keyboard.c

@@ -85,6 +85,7 @@ handle_keybinding(struct server *server, uint32_t modifiers, xkb_keysym_t sym)
 		}
 		for (size_t i = 0; i < keybind->keysyms_len; i++) {
 			if (xkb_keysym_to_lower(sym) == keybind->keysyms[i]) {
+				key_state_store_pressed_keys_as_bound();
 				actions_run(NULL, server, &keybind->actions, 0);
 				return true;
 			}
@@ -121,7 +122,7 @@ handle_compositor_keybindings(struct wl_listener *listener,
 
 	bool handled = false;
 
-	key_state_set_pressed(keycode,
+	key_state_set_pressed(event->keycode,
 		event->state == WL_KEYBOARD_KEY_STATE_PRESSED);
 
 	/*
@@ -152,9 +153,9 @@ handle_compositor_keybindings(struct wl_listener *listener,
 	 * If a press event was handled by a compositor binding, then do not
 	 * forward the corresponding release event to clients
 	 */
-	if (key_state_corresponding_press_event_was_bound(keycode)
+	if (key_state_corresponding_press_event_was_bound(event->keycode)
 			&& event->state == WL_KEYBOARD_KEY_STATE_RELEASED) {
-		key_state_bound_key_remove(keycode);
+		key_state_bound_key_remove(event->keycode);
 		return true;
 	}
 
@@ -247,7 +248,7 @@ keyboard_key_notify(struct wl_listener *listener, void *data)
 	if (!handled) {
 		wlr_seat_set_keyboard(wlr_seat, keyboard);
 		wlr_seat_keyboard_notify_key(wlr_seat, event->time_msec,
-					     event->keycode, event->state);
+			event->keycode, event->state);
 	}
 }
 

src/seat.c

@@ -9,6 +9,7 @@
 #include <wlr/types/wlr_touch.h>
 #include <wlr/util/log.h>
 #include "common/mem.h"
+#include "key-state.h"
 #include "labwc.h"
 
 static void
@@ -347,8 +348,19 @@ seat_focus_surface(struct seat *seat, struct wlr_surface *surface)
 		return;
 	}
 	struct wlr_keyboard *kb = &seat->keyboard_group->keyboard;
-	wlr_seat_keyboard_notify_enter(seat->seat, surface, kb->keycodes,
-		kb->num_keycodes, &kb->modifiers);
+
+	/*
+	 * Key events associated with keybindings (both pressed and released)
+	 * are not sent to clients. When changing surface-focus it is therefore
+	 * important not to send the keycodes of _all_ pressed keys, but only
+	 * those that were actually _sent_ to clients (that is, those that were
+	 * not bound).
+	 */
+	uint32_t *pressed_sent_keycodes = key_state_pressed_sent_keycodes();
+	int nr_pressed_sent_keycodes = key_state_nr_pressed_sent_keycodes();
+
+	wlr_seat_keyboard_notify_enter(seat->seat, surface,
+		pressed_sent_keycodes, nr_pressed_sent_keycodes, &kb->modifiers);
 
 	struct server *server = seat->server;
 	struct wlr_pointer_constraint_v1 *constraint =