From e77330bc3fe733412e92f4e90d797d31ee6c5652 Mon Sep 17 00:00:00 2001
From: Johan Malm <jgm323@gmail.com>
Date: Tue, 26 Sep 2023 17:51:54 +0100
Subject: [PATCH] keyboard: make keybind match stricter

...and avoid failing to send release events to clients for any keys that were
not absorbed by a keybind.

Do not match keybinds if there are other non-modifier keys (not part of any
defined bind) pressed at the same time.

Only store non-modifier keycodes in the key-state.c 'pressed' array.
This makes the call to wlr_seat_keyboard_notify_enter() in seat_focus()
consistent with the equivalent in sway (in seat_keyboard_notify_enter()).

Fixes: issue #1091
---
 include/key-state.h |  1 +
 src/key-state.c     |  6 ++++++
 src/keyboard.c      | 51 +++++++++++++++++++++++++++++++++++++--------
 3 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/include/key-state.h b/include/key-state.h
index a45b3494..fd029881 100644
--- a/include/key-state.h
+++ b/include/key-state.h
@@ -21,5 +21,6 @@ void key_state_store_pressed_keys_as_bound(void);
 bool key_state_corresponding_press_event_was_bound(uint32_t keycode);
 void key_state_bound_key_remove(uint32_t keycode);
 int key_state_nr_keys(void);
+int key_state_nr_pressed_keys(void);
 
 #endif /* LABWC_KEY_STATE_H */
diff --git a/src/key-state.c b/src/key-state.c
index f95d480c..06e193a7 100644
--- a/src/key-state.c
+++ b/src/key-state.c
@@ -102,3 +102,9 @@ key_state_nr_keys(void)
 {
 	return bound.nr_keys;
 }
+
+int
+key_state_nr_pressed_keys(void)
+{
+	return pressed.nr_keys;
+}
diff --git a/src/keyboard.c b/src/keyboard.c
index 0d5b4c2a..73b8c9fe 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -203,8 +203,34 @@ handle_compositor_keybindings(struct keyboard *keyboard,
 
 	bool handled = false;
 
-	key_state_set_pressed(event->keycode,
-		event->state == WL_KEYBOARD_KEY_STATE_PRESSED);
+	/*
+	 * keyboard_key_notify() is called before keyboard_key_modifier(), so
+	 * 'modifiers' refers to modifiers that were pressed before the key
+	 * event in hand. Consequently, we use is_modifier_key() to find out if
+	 * the key event being processed is a modifier.
+	 *
+	 * Sway solves this differently by saving the 'modifiers' state and
+	 * checking if it has changed each time we get to the equivalent of this
+	 * function. If it has changed, it concludes that the last key was a
+	 * modifier and then deletes it from the buffer of pressed keycodes.
+	 * For us the equivalent would look something like this:
+	 *
+	 * static uint32_t last_modifiers;
+	 * bool last_key_was_a_modifier = last_modifiers != modifiers;
+	 * last_modifiers = modifiers;
+	 * if (last_key_was_a_modifier) {
+	 *	key_state_remove_last_pressed_key(last_pressed_keycode);
+	 * }
+	 */
+
+	bool ismodifier = false;
+	for (int i = 0; i < translated.nr_syms; i++) {
+		ismodifier |= is_modifier_key(translated.syms[i]);
+	}
+	if (!ismodifier) {
+		key_state_set_pressed(event->keycode,
+			event->state == WL_KEYBOARD_KEY_STATE_PRESSED);
+	}
 
 	/*
 	 * Ignore labwc keybindings if input is inhibited
@@ -293,13 +319,7 @@ handle_compositor_keybindings(struct keyboard *keyboard,
 
 			/* cycle to next */
 			bool backwards = modifiers & WLR_MODIFIER_SHIFT;
-			/* ignore if this is a modifier key being pressed */
-			bool ignore = false;
-			for (int i = 0; i < translated.nr_syms; i++) {
-				ignore |= is_modifier_key(translated.syms[i]);
-			}
-
-			if (!ignore) {
+			if (!ismodifier) {
 				enum lab_cycle_dir dir = backwards
 					? LAB_CYCLE_DIR_BACKWARD
 					: LAB_CYCLE_DIR_FORWARD;
@@ -313,6 +333,19 @@ handle_compositor_keybindings(struct keyboard *keyboard,
 		goto out;
 	}
 
+	/*
+	 * A keybind is not considered valid if other keys are pressed at the
+	 * same time.
+	 *
+	 * In labwc, a keybind is defined by one/many modifier keys + _one_
+	 * non-modifier key. Returning early on >1 pressed non-modifier keys
+	 * avoids false positive matches where 'other' keys were pressed at the
+	 * same time.
+	 */
+	if (key_state_nr_pressed_keys() > 1) {
+		return false;
+	}
+
 	/*
 	 * Handle compositor keybinds
 	 *