Per-application window scaling in Xorg for high dpi display

Question

I am running Gnome Shell with a 4k monitor and there are a few applications that I use that don't scale at all with the high resolution.

Here is an example of LMMS, an application that hasn't yet been ported Qt 5, so it doesn't have high dpi scaling capabilities:

^{(Click images to enlarge)}

Is there any way to scale a specific X window without changing the display resolution?

My current solution is to half the dimensions of my display resolution, but this degrades the resolution of every other application that supports proper dpi scaling:

Answer 1

I finally managed to find a solution that scales old applications without any noticeable visual or performance degradation.

Thanks to kaueraal, you can now scale old applications using run_scaled. You can obtain the script from either his GitHub page or through AUR run_scaled-git if you are running Arch Linux.

Here is an example of two applications running side by side:

• Firefox with HiDPI support on the left
• LMMS running with run_scaled on the right

I discovered this script through the Arch Linux Wiki.

Answer 2

Without seeing the exact problem that you are running into I would suggest using

GDK_SCALE=x

or

GDK_DPI_SCALE=x

Before starting each application. You will likely have to manually change .desktop files or run from your shell prefixing the commands with GDK_SCALE=x

GDK_SCALE only allow interger values however GDK_DPI_SCALE=x allow for decimal values like i.e.GDK_DPI_SCALE=0.66

For other SDK based applications there are likely similar settings for respective kits. However since your problem is with gnome desktop I will provide this solution.

I haven't tried with a 4k monitor, but running GDK_DPI_SCALE=1.66 gnome-calculator will demo the solution.

Source: https://developer.gnome.org/gtk3/stable/gtk-x11.html

Answer 3

Vncdesk gives you a solution based on a local VNC client-server (see here)

It is not a complete solution for me because it gives some problems if the app need a window manager.