Bug 284924 - subpixel rendering disappears inside selection box since upgrading Qt to 4.8rc1
Summary: subpixel rendering disappears inside selection box since upgrading Qt to 4.8rc1
Status: RESOLVED UPSTREAM
Alias: None
Product: kde
Classification: I don't know
Component: general (show other bugs)
Version: unspecified
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: Unassigned bugs mailing-list
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-10-25 09:55 UTC by Victor Gavrish
Modified: 2011-10-25 14:32 UTC (History)
1 user (show)

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Latest Commit:
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subpixel rendering disappears. (39.96 KB, image/png)
2011-10-25 09:55 UTC, Victor Gavrish 		Details
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Description Victor Gavrish 2011-10-25 09:55:04 UTC 
Created attachment 64860 [details]
subpixel rendering disappears.

Version:           unspecified (using KDE 4.7.2) 
OS:                Linux

I noticed this happening in System Settings and Dolphin.

Reproducible: Didn't try

Steps to Reproduce:
1. Install Qt 4.8rc1
2. Open systemsettings.
3. Open kmag. Set zoom to 1:3.
4. Hover the mouse pointer over an item in systemsettings

Actual Results:  
The color fringing visible in kmag disappears.

Expected Results:  
Subpixel rendering all the way.
Comment 1 Christoph Feck 2011-10-25 12:07:27 UTC 
Which widget style are you using? I cannot reproduce.
Comment 2 Victor Gavrish 2011-10-25 12:11:53 UTC 
Ok, things I think might affect this:

1. qtcurve widget style ("flat" preset)
2. slight autohinting in fontconfig
3. droid sans font for interface
4. this might also be a bug of freetype2 with infinality patches that I'm using, although I don't see how it would only affect this specific aspect of KDE
Comment 3 Victor Gavrish 2011-10-25 12:37:13 UTC 
I removed infinality and installed standard freetype2 and I'm still experiencing this. I also tried changing everything else of the above and nothing helps. I tried Oxygen widget style, full TT hinting and DejaVu fonts. Also, subpixel rendering is permanently off in in the kickoff menu, on the taskbar, and on the clock, although I think that was the case even before qt 4.8rc1. Not sure if that's related or not.
Comment 4 Christoph Feck 2011-10-25 13:28:41 UTC 
I cannot reproduce with QtCurve 1.8.9.

Does "systemsettings --graphicssystem native" change the rendering?

Note that the Plasma texts are rendered to a QImage to apply the shadow effects, so it did not support subpixel hinting even before (there is already a bug about those cases).
Comment 5 Victor Gavrish 2011-10-25 13:35:27 UTC 
It does change the rendering (for the uglier), but the issue remains:

http://i.imgur.com/zyKpp.png
Comment 6 Victor Gavrish 2011-10-25 14:07:37 UTC 
> Note that the Plasma texts are rendered to a QImage to apply the shadow
effects, so it did not support subpixel hinting even before (there is already a
bug about those cases).

It is possible that the bug was present before I upgraded to Qt 4.8rc1.
Comment 7 Christoph Feck 2011-10-25 14:28:52 UTC 
Okey, I see the problem, it is only visible with animations enabled, I had them disabled via System Settings > Application Appearance > Style > Fine Tuning > Graphical effects.

The animation code renders the items to a QPixmap cache, and Qt no longer renders those texts with subpixel antialiasing.

For more information, see https://bugreports.qt.nokia.com/browse/QTBUG-22334
Comment 8 Victor Gavrish 2011-10-25 14:32:43 UTC 
Thanks for the workaround :D