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Bug 313646 - Corrupted fonts in GTK+ 2.8.x if RenderAccel set to "true"
Corrupted fonts in GTK+ 2.8.x if RenderAccel set to "true"
Status: RESOLVED NOTGNOME
Product: gtk+
Classification: Platform
Component: .General
2.8.x
Other All
: Normal major
: ---
Assigned To: gtk-bugs
gtk-bugs
Depends on:
Blocks:
 
 
Reported: 2005-08-16 17:16 UTC by Wojciech Milkowski
Modified: 2005-12-22 14:56 UTC
See Also:
GNOME target: ---
GNOME version: 2.11/2.12


Attachments
corrupted gVim 1 (31.98 KB, image/png)
2005-08-16 17:18 UTC, Wojciech Milkowski
Details
corrupted gVim 2 (44.47 KB, image/png)
2005-08-16 17:19 UTC, Wojciech Milkowski
Details
corrupted BMP (24.36 KB, image/png)
2005-08-17 00:01 UTC, Wojciech Milkowski
Details

Description Wojciech Milkowski 2005-08-16 17:16:40 UTC
Please describe the problem:
New 2.8.0 release of GTK+ (and its components: Pango 1.9.1, Cairo 0.9.2, Atk
1.10.1, Freetype 2.1.10) has occasional problems with font rendering. It happens
mostly during fast menu redraws, or in applications like gVim.
I've attached two screenshots that shows this bug (on gVim i can reproduce it
every time).

My /etc/fonts/local.conf:

<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<!-- /etc/fonts/local.conf file for local customizations -->
<fontconfig>
<!--
  Enable sub-pixel rendering
        <match target="font">
                <edit name="rgba" mode="assign"><const>rgb</const></edit>
        </match>
-->
<!-- Auto Antialais -->
    <match target="font">
        <test name="pixelsize" compare="more_eq">
            <double>7.0</double>
        </test>
        <test name="pixelsize" compare="less_eq">
            <double>14.0</double>
        </test>
        <edit name="antialias" mode="assign">
            <bool>false</bool>
        </edit>
    </match>

</fontconfig>


Steps to reproduce:
1. install gtk+ 2.8.0
2. install an run gVim


Actual results:


Expected results:


Does this happen every time?


Other information:
Comment 1 Wojciech Milkowski 2005-08-16 17:18:23 UTC
Created attachment 50802 [details]
corrupted gVim 1
Comment 2 Wojciech Milkowski 2005-08-16 17:19:00 UTC
Created attachment 50803 [details]
corrupted gVim 2
Comment 3 Wojciech Milkowski 2005-08-17 00:01:43 UTC
Created attachment 50820 [details]
corrupted BMP
Comment 4 Wojciech Milkowski 2005-08-17 13:01:42 UTC
I discovered that it happens only when font's antialiasing is disabled. For
antialaiased fonts everything works OK, so I changed topic to comply that.
Comment 5 Bernhard Walle 2005-10-08 11:38:51 UTC
Same problem here with a installation of SuSE 10.0 which includes gtk 2.8.2. 
Comment 6 Bernhard Walle 2005-10-08 11:58:44 UTC
Disabling RenderAccel in xorg.conf or using the OpenSource nv driver solved the
problem here. Seems to be a bug in nVidia driver.
Comment 7 Wojciech Milkowski 2005-10-08 21:37:03 UTC
I confirm that, disabling RenderAccel solves the problem with nVidia drivers
version 76.67.
Comment 8 Eike Hein 2005-12-18 18:59:42 UTC
More data in this Gentoo bug: http://bugs.gentoo.org/show_bug.cgi?id=113123
Comment 9 Christian Kirbach 2005-12-18 21:33:00 UTC
Eike, you get the problem with the nvidia driver as well, right?

Wojciech : does switching to the free nv driver remedy for you as well?
Comment 10 Christian Kirbach 2005-12-18 22:36:57 UTC
So this seems to be an NVidia driver issue, marking this NOTGNOME.
Please report this issue to NVidia.


<loopback> nazgul: using open source driver and keeping RenderAccel fix font rendering, removing RenderAccel and keeping closed source driver fix font rendering too
<loopback> nazgul: so, yes, I may be an nvidia driver issue, or at least is seems so.
Comment 11 Luca Cavalli 2005-12-18 22:44:41 UTC
I hope you can at least understand my funny IRC english :)
Comment 12 Wojciech Milkowski 2005-12-19 03:38:31 UTC
Seems to work OK with free nv driver & RenderAccel set to "true". Still doesn't work with newer nvidia release 81.74.
Comment 13 Christian Kirbach 2005-12-19 13:01:28 UTC
Can anyone downgrade the driver and pinpoint it to a release that causes this?
Might be helpful.
Comment 14 Luca Cavalli 2005-12-19 21:03:14 UTC
Tested with the oldest driver I can install, version 7167. The very same problem with RenderAccel, solved by disabling the option. Tried also versions 6629 and 6106, but driver installation aborted before completition.
Comment 15 Ashley Bostock 2005-12-20 18:15:31 UTC
http://forums.gentoo.org/viewtopic-t-393284-highlight-gtk+fonts.html See the post from Sho who doesn't even use nvidia's binary driver and still gets the problem.

Also I have antialiasing turned on and I still see the problem.
Comment 16 Eike Hein 2005-12-20 18:37:04 UTC
Actually, I was mistaken - I do in fact use the nVidia binary driver with RenderAccel enabled. Disabling it solves the problem.

To explain how I made this mistake: The GTK+ apps that exhibited the broken font rendering are actually running on a remote machine, which I control from afar using the terminal server technology NX (www.nomachine.com). Now, the X server on that remote box does use the "nv" driver, however unlike VNC which essentially transmits screen captures of the remote desktop, NX transmits X11 protocol primitives (as I know only now). The local client application is an X server instance running in some kind of Xnest-like setup - and my local X server uses the "nvidia" driver.

Sorry for the confusion. We've nailed the issue, then.
Comment 17 Christian Kirbach 2005-12-20 23:24:22 UTC
Are you all on Gentoo Linux? If not, please make yourself heard.
I have the suspicion you are all on it - this cannot be coincidence.

Retitling since the option "RenderAccel" seems to trigger this.
Also all but one use the closed-source NVida binary driver.
I'll try to pull him/her into the discussion.

As this has stirred many people I will reopen the report and try to poke some of the experts :)
Comment 18 Luca Cavalli 2005-12-20 23:47:43 UTC
No, I'm on Slackware :)
Comment 19 Eike Hein 2005-12-21 00:12:00 UTC
I'm on Gentoo, yep. Using gcc 3.4.4 on x86 with sane CFLAGS (-march=athlon-xp -O2 -pipe).
Comment 20 Stephen P. Becker 2005-12-21 13:37:13 UTC
(In reply to comment #17)
> Are you all on Gentoo Linux? If not, please make yourself heard.
> I have the suspicion you are all on it - this cannot be coincidence.

There are at least two folks not on gentoo in this bug report.  One SUSE, one Slackware.


> Retitling since the option "RenderAccel" seems to trigger this.
> Also all but one use the closed-source NVida binary driver.
> I'll try to pull him/her into the discussion.

It really does seem to be nvidia binary related in some way.  I've talked to some folks who claim to have the same problem, and it always ends up that they were either mistaken about their driver, or they were actually having a different problem for which "font corruption" sounded like what they had.

While it is easy to blame the nvidia binary drivers, don't yet discount the possibility that they are simply uncovering some obscure bug in GTK+.


> As this has stirred many people I will reopen the report and try to poke some
> of the experts :)

I can provide some additional information here which might give a good starting point.

I first noticed the problem when I upgraded to mozilla-firefox-1.5.  In my frustration at not being able to use the web browser because the corruption was so horrible, I nuked it from my system.  Well, a couple days later I got a bug up my butt and decided to reinstall firefox and see if I could debug this a bit, except I didn't want to wait for it to compile, so I installed the official binary release from upstream.  I could *not* reproduce it with this, even though it is linked against the very same gtk+ libs.  Other folks in the Gentoo bug for this problem have noticed the same thing.  This might be a good place to start, as I have no idea why some pre-compiled binary which is using the same libs to render widgets and display fonts wouldn't reproduce the corruption.

Secondly, this problem doesn't show up for everybody who uses nvidia+RenderAccel, including at least two of the Gentoo GNOME team members.  It actually seems like all of the people who have spoken up (on the Gentoo side of things) are KDE users.  Furthermore, one of our developers (who normally runs KDE) started Fluxbox, and could not reproduce the corruption in that environment.  I'm starting to get a feeling that QT and GTK+ aren't coexisting very nicely in terms of the RENDER extension, however I can't say which one is truly at fault.  I've got a couple ideas for testing this, and I'll report back if I find out anything.
Comment 21 Eike Hein 2005-12-22 12:02:06 UTC
In this web forum thread, an nVidia engineer has responded to a description of the problem: http://www.nvnews.net/vbulletin/showthread.php?t=61763

Full quote:

"There are currently known issues with RenderAccel. We hope to address most, if not all of the known issues in the first driver release of 2006.

Thanks,
Lonni"