compositor: add a way to change the keyboard locks

This adds a function weston_keyboard_set_locks() which can be used to
change the state of the num lock and the caps locks, changing the leds too.
Only the evdev and libinput backends supports this, since it doesn't make
sense for embedded sessions.

Tested-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

src/compositor.h

@@ -68,6 +68,11 @@ enum weston_keyboard_modifier {
 	MODIFIER_SHIFT = (1 << 3),
 };
 
+enum weston_keyboard_locks {
+	WESTON_NUM_LOCK = (1 << 0),
+	WESTON_CAPS_LOCK = (1 << 1),
+};
+
 enum weston_led {
 	LED_NUM_LOCK = (1 << 0),
 	LED_CAPS_LOCK = (1 << 1),
@@ -393,6 +398,13 @@ weston_keyboard_start_grab(struct weston_keyboard *device,
 			   struct weston_keyboard_grab *grab);
 void
 weston_keyboard_end_grab(struct weston_keyboard *keyboard);
+int
+/*
+ * 'mask' and 'value' should be a bitwise mask of one or more
+ * valued of the weston_keyboard_locks enum.
+ */
+weston_keyboard_set_locks(struct weston_keyboard *keyboard,
+			  uint32_t mask, uint32_t value);
 
 struct weston_touch *
 weston_touch_create(void);

src/input.c

@@ -1062,6 +1062,58 @@ notify_axis(struct weston_seat *seat, uint32_t time, uint32_t axis,
 				     value);
 }
 
+WL_EXPORT int
+weston_keyboard_set_locks(struct weston_keyboard *keyboard,
+			  uint32_t mask, uint32_t value)
+{
+#ifdef ENABLE_XKBCOMMON
+	uint32_t serial;
+	xkb_mod_mask_t mods_depressed, mods_latched, mods_locked, group;
+	xkb_mod_mask_t num, caps;
+
+	/* We don't want the leds to go out of sync with the actual state
+	 * so if the backend has no way to change the leds don't try to
+	 * change the state */
+	if (!keyboard->seat->led_update)
+		return -1;
+
+	mods_depressed = xkb_state_serialize_mods(keyboard->xkb_state.state,
+						XKB_STATE_DEPRESSED);
+	mods_latched = xkb_state_serialize_mods(keyboard->xkb_state.state,
+						XKB_STATE_LATCHED);
+	mods_locked = xkb_state_serialize_mods(keyboard->xkb_state.state,
+						XKB_STATE_LOCKED);
+	group = xkb_state_serialize_group(keyboard->xkb_state.state,
+                                      XKB_STATE_EFFECTIVE);
+
+	num = (1 << keyboard->xkb_info->mod2_mod);
+	caps = (1 << keyboard->xkb_info->caps_mod);
+	if (mask & WESTON_NUM_LOCK) {
+		if (value & WESTON_NUM_LOCK)
+			mods_locked |= num;
+		else
+			mods_locked &= ~num;
+	}
+	if (mask & WESTON_CAPS_LOCK) {
+		if (value & WESTON_CAPS_LOCK)
+			mods_locked |= caps;
+		else
+			mods_locked &= ~caps;
+	}
+
+	xkb_state_update_mask(keyboard->xkb_state.state, mods_depressed,
+			      mods_latched, mods_locked, 0, 0, group);
+
+	serial = wl_display_next_serial(
+				keyboard->seat->compositor->wl_display);
+	notify_modifiers(keyboard->seat, serial);
+
+	return 0;
+#else
+	return -1;
+#endif
+}
+
 #ifdef ENABLE_XKBCOMMON
 WL_EXPORT void
 notify_modifiers(struct weston_seat *seat, uint32_t serial)