broken window rendering: 3/4 black with Cinnamon + HiDPI

[totaam]

Issue migrated from trac ticket # 2492

component: client | priority: major | resolution: fixed

2019-11-25 23:58:11: doegox created the issue

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When using xpra as client on a Cinnamon (4.2.4-2 on Debian) with HiDPI settings, the xpra windows are rendered wrongly, see screenshot.
The image of the window (from any X app) is cropped to the lower left quarter, the other three quarters of the window are black.
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[[Image(https://i.imgur.com/F7ObhbV.png)]]
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If I disable Cinnamon HiDPI settings (via System Settings / Desktop Scaling or in CLI: "gsettings set org.cinnamon.desktop.interface scaling-factor 1", the problem disappears immediately in the currently opened xpra windows.

E.g.:

Cinnamon initially configured for HiDPI

$ xpra attach ssh:nuc:100 --start=gnome-terminal
2019-11-26 00:40:47,497 Xpra GTK3 X11 client version 3.0.2-24387 64-bit
2019-11-26 00:40:47,810  running on Linux Debian testing bullseye
2019-11-26 00:40:47,812  window manager is 'Mutter (Muffin)'
2019-11-26 00:40:48,886 GStreamer version 1.16.1 for Python 3.7.5 64-bit
2019-11-26 00:40:49,099 No OpenGL_accelerate module loaded: No module named 'OpenGL_accelerate'
2019-11-26 00:40:49,522 OpenGL enabled with Mesa DRI Intel(R) HD Graphics 530 (Skylake GT2)
2019-11-26 00:40:49,709 Connected (version 2.0, client OpenSSH_7.4p1)
2019-11-26 00:40:50,139 Authentication (publickey) successful!
2019-11-26 00:40:50,272  keyboard settings: rules=evdev, model=pc105, layout=us
2019-11-26 00:40:50,284  desktop size is 1920x1080 with 1 screen:
2019-11-26 00:40:50,285   :0.0 (338x190 mm - DPI: 144x144) workarea: 3840x2110
2019-11-26 00:40:50,285     SHP eDP-1 (346x194 mm - DPI: 140x141)
2019-11-26 00:40:50,307 no ethtool interface speed available for wlp2s0
2019-11-26 00:40:50,999 enabled remote logging
2019-11-26 00:40:51,001 Xpra GTK3 X11 server version 3.0.2-24387 64-bit
2019-11-26 00:40:51,001  running on Linux Debian 9.11 stretch
2019-11-26 00:40:51,017 Attached to ssh://phil@nuc/100
2019-11-26 00:40:51,017  (press Control-C to detach)

2019-11-26 00:40:51,160 server does not support xi input devices
2019-11-26 00:40:51,161  server uses: xtest

=> getting a 3/4 black terminal, cf screenshot

=> typing in another term:

gsettings set org.cinnamon.desktop.interface scaling-factor 1

=> xpra log:

2019-11-26 00:42:15,605 sending updated screen size to server: 3840x2160 with 1 screens
2019-11-26 00:42:15,605   :0.0 (338x190 mm - DPI: 288x288) workarea: 3840x2135
2019-11-26 00:42:15,606     SHP eDP-1 (346x194 mm - DPI: 281x282)

=> and xpra terminal appearance is now correct.

=> typing in another term:

gsettings set org.cinnamon.desktop.interface scaling-factor 2

=> the initial problem reappears

=> xpra log:

2019-11-26 00:42:30,015 sending updated screen size to server: 1920x1080 with 1 screens
2019-11-26 00:42:30,016   :0.0 (338x190 mm - DPI: 144x144) workarea: 3840x2110
2019-11-26 00:42:30,017     SHP eDP-1 (346x194 mm - DPI: 140x141)

[totaam]

2019-11-26 00:00:48: doegox uploaded file 2492.zip (80.2 KiB)

xpra settings

[totaam]

2019-11-26 03:14:45: antoine changed owner from antoine to doegox

[totaam]

2019-11-26 03:14:45: antoine commented

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This was meant to have been fixed in 24282, but maybe GTK has changed things yet again?
Can you please try to run the client with:

GDK_SCALE=1 xpra attach ..

[totaam]

2019-11-26 07:54:20: antoine changed component from android to client

[totaam]

2019-11-26 10:02:06: doegox commented

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GDK_SCALE=1 xpra attach ..
has no effect

But, if I comment unsetenv("GDK_SCALE") in main.py and run
GDK_SCALE=1 xpra attach ..
then the window decoration is properly drawn around the terminal (but everything is twice small, as for the terminal of my screenshot)

Note that by default GDK_SCALE is not defined and if I run
xpra attach .., no matter if unsetenv("GDK_SCALE") is commented or not, I have the same 3/4 black issue.

[totaam]

2019-11-26 10:06:29: doegox commented

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so for now I'm using

    #unsetenv("GDK_SCALE")
    os.environ["GDK_SCALE"]="1"

[totaam]

2019-11-26 11:49:58: antoine commented

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But, if I comment unsetenv("GDK_SCALE") in main.py
Doh, of course, since we then unset it!

Applied in r24484.
Can I close this ticket?

[totaam]

2019-11-26 18:50:46: doegox commented

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yes, thanks!!

[totaam]

2019-12-25 11:38:36: antoine changed status from new to closed

[totaam]

2019-12-25 11:38:36: antoine set resolution to fixed