[Webkit-unassigned] [Bug 69614] New: [Qt] True/FreeType Font Rendering Issue at Large Size

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=69614

           Summary: [Qt] True/FreeType Font Rendering Issue at Large Size
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: All
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: Major
          Priority: P3
         Component: New Bugs
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: rudi at rudiv.se


Created an attachment (id=110120)
 --> (https://bugs.webkit.org/attachment.cgi?id=110120&action=review)
Font Rendering differences across size

We have a large canvas that is intended to draw text and images, and scale between different sizes. This works fine for most rendering engines (including GTK+ WebKit, Chromium/Chrome port of WebKit and Safari itself), however QTWebKit has an issue when the font-sizes we render get too large.

On the same machine, when rendering TheanoModern between QtWebKit and Chrome, QtWebKit exhibits the attached issue where certain characters (containing curves) are rendered incorrectly. As shown in the attachment 'qtwebkitbug.png' you can see the text when rendered at 69px (Scaled up from 30 at a factor of 2.3) which is correct, however bumping up the scale to 2.5 (81px) and above always exhibits this issue.

As mentioned before, QtWebKit is the only WebKit port that displays this issue, and it is only on RH/Arch based linuxes which makes me believe it may be a Free/TrueType library that is not installed, thus forcing Qt to use it's own renderer rather than an external library. I have ensured that the FreeType libraries are up to date on all machines to no avail, perhaps there is another library that may need installing.

The font TheanoModern is available here for testing - http://www.fontsquirrel.com/fonts/Theano-Modern

Affected systems:
Fedora 15 - Linux 2.6.38.6-2.rc1.fc15.x86_64 #1 SMP x86_64
Red Hat Enterprise Linux 5 - Linux 2.6.18-194.17.1.el5 #1 SMP x86_64
Arch Linux - Linux Kernel 3.0, x86_64, unknown full kernel string at this time.

Unaffected (Confirmed) systems:
Ubuntu 10.10 x86_64, Ubuntu 11.04 i386, Mac OSX 10.6

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