[Bug 84115] New: Broken line drawing with cairo graphics using SNA and UXA

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=84115

          Priority: medium
            Bug ID: 84115
          Assignee: chris at chris-wilson.co.uk
           Summary: Broken line drawing with cairo graphics using SNA and
                    UXA
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: maurizio.berti at gmail.com
          Hardware: x86 (IA32)
            Status: NEW
           Version: 7.4 (2008.09)
         Component: Driver/intel
           Product: xorg

As reported on cairo graphics mailing list (here:
http://lists.cairographics.org/archives/cairo/2014-September/025623.html ), it
looks like that the accelerated line drawing is broken while drawing arcs with
cairo, and this is visible when the line width is way bigger than 1 pixel.
Using UXA the beginning of the arc is not straight, as shown here:
http://jidesk.net/sypy/strangearc2.jpg
Using SNA there is also a seaming issue as shown here:
http://jidesk.net/sypy/strangearc-bryce.png

After consulting users on #cairo on FreeNode, the issue is confirmed, and they
suggested me to report here, since it looks like it is related to intel's X
acceleration on newer drivers. I am using a i5-3570K for graphics too, which is
an Ivy Bridge architecture, but I suppose that the problem affects Sandy Bridge
architectures also.

Unfortunally I am no programmer, so I am just supposing a lot of things
figuring out techno-babble I barely understand. I'm pretty sure that you could
find the source of this issue anyway, and eventually bounce back to cairo
developers if you find out that this is only a cairo related bug.

Thanks,
Maurizio

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20140920/eb7772b5/attachment-0001.html>