Client: Allow inheritance of key translation

Use a virtual method keysymToQtKey for Qt key code translation, so that
it can be customized by a descendant class if needed.

Change-Id: I3b48346a63e2c6f134230fe15279faa95abe11a0
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

src/plugins/platforms/wayland/qwaylandinputdevice.cpp

@@ -1268,7 +1268,7 @@ void QWaylandInputDevice::Keyboard::keyboard_key(uint32_t serial, uint32_t time,
 
         Qt::KeyboardModifiers modifiers = mParent->modifiers();
 
-        int qtkey = QXkbCommon::keysymToQtKey(sym, modifiers, mXkbState.get(), code);
+        int qtkey = keysymToQtKey(sym, modifiers, mXkbState.get(), code);
         QString text = QXkbCommon::lookupString(mXkbState.get(), code);
 
         QEvent::Type type = isDown ? QEvent::KeyPress : QEvent::KeyRelease;

src/plugins/platforms/wayland/qwaylandinputdevice_p.h

@@ -263,6 +263,12 @@ public:
 
     struct ::wl_keyboard *wl_keyboard() { return QtWayland::wl_keyboard::object(); }
 
+#if QT_CONFIG(xkbcommon)
+    virtual int keysymToQtKey(xkb_keysym_t keysym, Qt::KeyboardModifiers modifiers, xkb_state *state, xkb_keycode_t code) {
+        return QXkbCommon::keysymToQtKey(keysym, modifiers, state, code);
+    }
+#endif
+
 private slots:
     void handleFocusDestroyed();
     void handleFocusLost();