Windows: Work-around misreporting of Script and Roman

Two legacy bitmap fonts are misreported as TMPF_VECTOR on
Windows: Roman and Script. This causes them to be marked as
scalable, and the automatic fallback to NativeRendering in
Qt Quick does not kick in - causing the text elements to look
empty instead.

To work around this, we exploit the peculiarity that the type
of these two fonts is reported as "0" in the enumeration, which is
not a valid value. No other fonts on the system is reported as type
0, so we simply detect this error case and mark the fonts as
non-scalable, which is the safer choice.

[ChangeLog][Windows] Fixed text in "Roman" and "Script" bitmap
fonts not showing in Qt Quick applications.

Fixes: QTBUG-85826
Change-Id: Id889f0dedb1d529e6dd64c6da9e17e303f4a9d04
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
(cherry picked from commit a1e405ce11eb6760ccca13cf1b4e5d20fa3916e9)

1 files changed, 3 insertions, 1 deletions

diff --git a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp
index 6785578ee1..21f4f7d879 100644
--- a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp
+++ b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp
@@ -1038,7 +1038,9 @@ static bool addFontToDatabase(QString familyName,
     const QString foundryName; // No such concept.
     const bool fixed = !(textmetric->tmPitchAndFamily & TMPF_FIXED_PITCH);
     const bool ttf = (textmetric->tmPitchAndFamily & TMPF_TRUETYPE);
-    const bool scalable = textmetric->tmPitchAndFamily & (TMPF_VECTOR|TMPF_TRUETYPE);
+    const bool unreliableTextMetrics = type == 0;
+    const bool scalable = (textmetric->tmPitchAndFamily & (TMPF_VECTOR|TMPF_TRUETYPE))
+                          && !unreliableTextMetrics;
     const int size = scalable ? SMOOTH_SCALABLE : textmetric->tmHeight;
     const QFont::Style style = textmetric->tmItalic ? QFont::StyleItalic : QFont::StyleNormal;
     const bool antialias = false;