Qt5 and (lack of!) font rendering quality (Linux/X11)

  • I'm a bit of a font freak, so I have "bohoomil"'s Ultimate version of the Infinality patches to libfreetype6 and fontconfig installed. It does wonders to my KDE4-based desktop, giving text a quality that's just about as good as with MS Window's ClearType (using Segoe UI semi-bold as my desktop font) and better than OS X's font rendering.

    Recently I have been playing a bit with "Project Neon5", (K)Ubuntu's KDE Frameworks 5 playground, to get a preview of what's supposed to become the next KDE desktop. It's built atop Qt 5.3.2 .

    Font rendering is horrible when starting KF5 applications from under a KDE4 session: blocky and something is clearly off with RGB antialiasing. Thinking it might be due to running beta-quality software in a "subsession" rather than a standalone session, I thought I'd had a look at "pure" Qt5 from the official (K)Ubuntu repos. That's Qt 5.2.1 to be exact.

    Font rendering is better here, but it's still a far cry from being as nice as under Qt4. Part of that is due to Qt5 not respecting my choice of fonts (picking an unknown other font) but it also seems there's no distinction being made between medium (semi-bold) and bold, making everything look either too heavy or too light. I already have to work around this "feature" to treat semi-bold fonts as regular bold in Qt on OS X (Qt4 and Qt5 are handicapped alike in this aspect), I REALLY hope that Qt5 on Linux won't follow suit ...

    Thoughts, reactions or other feedback welcome!


  • Lifetime Qt Champion


    Interesting points you have. You should rather bring this topic to the interest mailing list. You'll find there Qt's developers/maintainers. This forum is more user oriented.

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