Wire up Compose support in libuterm

Feed all key events into the Compose state and use the resulting
keysyms.

src/uterm_input_internal.h

@@ -53,6 +53,7 @@ struct uterm_input_dev {
 	char *node;
 	struct ev_fd *fd;
 	struct xkb_state *state;
+	struct xkb_compose_state *compose_state;
 	/* Used in sleep/wake up to store the key's pressed/released state. */
 	char key_state_bits[SHL_DIV_ROUND_UP(KEY_CNT, CHAR_BIT)];
 

src/uterm_input_uxkb.c

@@ -242,6 +242,15 @@ int uxkb_dev_init(struct uterm_input_dev *dev)
 		goto err_timer;
 	}
 
+	if (dev->input->compose_table) {
+		dev->compose_state = xkb_compose_state_new(
+						dev->input->compose_table,
+						0);
+		if (!dev->compose_state)
+			llog_warn(dev->input, "cannot create compose state, "
+				  "disabling compose support");
+	}
+
 	return 0;
 
 err_timer:
@@ -251,6 +260,7 @@ int uxkb_dev_init(struct uterm_input_dev *dev)
 
 void uxkb_dev_destroy(struct uterm_input_dev *dev)
 {
+	xkb_compose_state_unref(dev->compose_state);
 	xkb_state_unref(dev->state);
 	ev_eloop_rm_timer(dev->repeat_timer);
 }
@@ -427,19 +437,40 @@ int uxkb_dev_process(struct uterm_input_dev *dev,
 		     uint16_t key_state, uint16_t code)
 {
 	struct xkb_state *state;
+	struct xkb_compose_state *compose_state;
 	xkb_keycode_t keycode;
 	const xkb_keysym_t *keysyms;
+	xkb_keysym_t one_sym;
 	int num_keysyms, ret;
+	enum xkb_compose_status compose_status;
 	enum xkb_state_component changed;
 
 	if (key_state == KEY_REPEATED)
 		return -ENOKEY;
 
 	state = dev->state;
+	compose_state = dev->compose_state;
 	keycode = code + EVDEV_KEYCODE_OFFSET;
 
 	num_keysyms = xkb_state_key_get_syms(state, keycode, &keysyms);
 
+	one_sym = XKB_KEY_NoSymbol;
+	if (num_keysyms == 1) {
+		/* See: https://bugs.freedesktop.org/show_bug.cgi?id=67167 */
+		one_sym = xkb_state_key_get_one_sym(state, keycode);
+		keysyms = &one_sym;
+	}
+
+	compose_status = XKB_COMPOSE_NOTHING;
+	if (compose_state && key_state == KEY_PRESSED) {
+		/* XKB_KEY_NoSymbol cancels the current compose sequence. */
+		xkb_compose_state_feed(compose_state, one_sym);
+
+		compose_status = xkb_compose_state_get_status(compose_state);
+		if (compose_status == XKB_COMPOSE_COMPOSED)
+			one_sym = xkb_compose_state_get_one_sym(compose_state);
+	}
+
 	changed = 0;
 	if (key_state == KEY_PRESSED)
 		changed = xkb_state_update_key(state, keycode, XKB_KEY_DOWN);
@@ -452,6 +483,10 @@ int uxkb_dev_process(struct uterm_input_dev *dev,
 	if (num_keysyms <= 0)
 		return -ENOKEY;
 
+	if (compose_status == XKB_COMPOSE_COMPOSING ||
+	    compose_status == XKB_COMPOSE_CANCELLED)
+		return -ENOKEY;
+
 	ret = uxkb_dev_fill_event(dev, &dev->event, keycode, num_keysyms,
 				  keysyms);
 	if (ret)
@@ -524,4 +559,7 @@ void uxkb_dev_wake_up(struct uterm_input_dev *dev)
 	}
 
 	uxkb_dev_update_keyboard_leds(dev);
+
+	if (dev->compose_state)
+		xkb_compose_state_reset(dev->compose_state);
 }