Refactor QXcbKeyboard::updateModifiers()

The current implementation is poorly documented and hides the mapping
between keysyms and modifier bits.
This changeset adds documentation about the inner workings and makes
the keysym/modifier bit mapping reusable. (The latter will be needed for
xkb keymap synthesis if the XKEYBOARD extension is unavailable.)

Change-Id: I70c6d204b2357365db4dafeda680132ab6823ca3
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbkeyboard.h b/src/plugins/platforms/xcb/qxcbkeyboard.h
index 7f1c51fab8..1e3e97d1ec 100644
--- a/src/plugins/platforms/xcb/qxcbkeyboard.h
+++ b/src/plugins/platforms/xcb/qxcbkeyboard.h
@@ -96,6 +96,8 @@ protected:
     void clearXKBConfig();
     // when XKEYBOARD not present on the X server
     void updateModifiers();
+    typedef QMap<xcb_keysym_t, int> KeysymModifierMap;
+    KeysymModifierMap keysymsToModifiers();
     // when XKEYBOARD is present on the X server
     void updateVModMapping();
     void updateVModToRModMapping();