qxkbcommon: Keep lower case as Qt key when upper case is not in Latin1

Upper-casing a Latin1 character might move it out of Latin1 range,
for example U+00B5 MICRO SIGN, which upper-case equivalent is
U+039C GREEK CAPITAL LETTER MU. If that's the case, then map the
original lower-case character.

Fixes: QTBUG-93858
Pick-to: 5.15 6.0 6.1
Change-Id: Ibd86fbb7c70d620c0884015ec1c40aa6351e6320
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Andrey Butirsky <butirsky@gmail.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/gui/platform/unix/qxkbcommon.cpp b/src/gui/platform/unix/qxkbcommon.cpp
index 3db84097c7..f53864cba1 100644
--- a/src/gui/platform/unix/qxkbcommon.cpp
+++ b/src/gui/platform/unix/qxkbcommon.cpp
@@ -545,7 +545,15 @@ static int keysymToQtKey_internal(xkb_keysym_t keysym, Qt::KeyboardModifiers mod
         // numeric keypad keys
         qtKey = Qt::Key_0 + (keysym - XKB_KEY_KP_0);
     } else if (QXkbCommon::isLatin1(keysym)) {
+        // Upper-case first, since Qt::Keys are defined in terms of their
+        // upper-case versions.
         qtKey = QXkbCommon::qxkbcommon_xkb_keysym_to_upper(keysym);
+        // Upper-casing a Latin1 character might move it out of Latin1 range,
+        // for example U+00B5 MICRO SIGN, which upper-case equivalent is
+        // U+039C GREEK CAPITAL LETTER MU. If that's the case, then map the
+        // original lower-case character.
+        if (!QXkbCommon::isLatin1(qtKey))
+            qtKey = keysym;
     } else {
         // check if we have a direct mapping
         xkb2qt_t searchKey{keysym, 0};