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Issue metadata

Status: WontFix
Owner:
Closed: Jun 2018
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux
Pri: 2
Type: Bug



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For HiDPI monitors, in KDE Plasma, "GTK Theme" window controls are blurry when system titlebar is hidden

Reported by battagli...@gmail.com, Jun 12 2018

Issue description

UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.79 Safari/537.36

Steps to reproduce the problem:
1. Go to preferences
2. Uncheck "Use system titlebar and borders"
3. Click "GTK+ Theme"

I'm running KDE Plasma 5.12.5 in Kubuntu 18.04, HiDPI scaling set to 2.0. I have GDK_SCALE=2.0 and GDK_DPI_SCALE=0.5, which are the correct settings for GTK3 scaling. All scaling works in Chrome/Chromium except for the window controls.

What is the expected behavior?
The window controls scale correctly without upsampling interpolation artifacts

What went wrong?
The window controls are blurry and have upsampling interpolation artifacts

Did this work before? N/A 

Chrome version: 67.0.3396.79  Channel: stable
OS Version: Kubuntu 18.04
Flash Version: Disabled

Strangely, this problem doesn't happen on my KDE Neon install (the version using Ubuntu Trusty), only on this one. In Kubuntu we're running version 67.0.3396.79. In Neon it says there are no upgrades and I believe it's the same version, but the window controls work flawlessly.

The attached picture is of Chrome, but the problem happens identically in Chromium as well.
 
Screenshot_20180612_015542.png
14.9 KB View Download
Labels: Needs-Triage-M67
Cc: pbomm...@chromium.org thomasanderson@chromium.org
Owner: thomasanderson@chromium.org
Status: WontFix (was: Unconfirmed)
This happens because the KDE GTK theme uses bitmaps for those buttons, and there's not enough space available in Chrome's tabstrip to display the full button with margin, so it must be downsized.  There's nothing we can really do here, unfortunately.  I'd try filing a bug with the theme to get them to use vector graphics instead of bitmaps.
The size isn't the problem, or that they're being scaled down. The artifact here comes from it being *upsampled* on HiDPI. They are taking the small buttons at normal res, and then on HiDPI, just upsampling them by 2, rather than using higher-res buttons. Perhaps the theme is loading the wrong button images.

Chrome should be using the HiDpi resources, but they're getting scaled down.

Try running 'google-chrome-stable --force-device-scale-factor=1' and check if the icons are still blurry.
Here is the version with the scale factor set to 1. On my screen it looks like they're still scaled down relative to the usual Breeze theme, but aren't blurry.

When I set the factor to 2, it looks like they're taking the same low-DPI image, but naively interpolating by a factor of 2.

It could be that this works in Neon vs Kubuntu because the latter is using a different version of the Breeze theme than the former. Where is the theme stored?
Screenshot_20180612_192843.png
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Sorry, potato quality png here makes *everything* look blurry, but they're crisp on my screen -- I'll get a better pic.
When you unmaximize the window, is it no longer blurry?
No, still blurry. See attached.

I note that this is also blurry in Firefox, so I suspect it's a problem with KDE's Breeze theme as ported to these two applications in Kubuntu 18.04. I hadn't realized this was specific to the theme, so I guess this is all a KDE regression.
Screenshot_20180612_194019.png
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Note that if I change the GTK theme away from Breeze, there's no problem. See attached. However, the Breeze GTK theme works without scaling issues on other apps. It's only in Chromium (and strangely Firefox) that it's broken.
Screenshot_20180612_195210.png
15.6 KB View Download

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