HiDPI scaling for non-aware applications

xorg

Current situation

I have a 15" 3200×1800 screen, which is referred to as Retina or HiDPI. Using Linux Mint Cinnamon, I already have a desktop that scales nicely – but that's pretty much it. Besides Firefox proprietary setting for HiDPI screens, other applications usually only have fonts scaled, without window layouts taking that into account.

Question

Is it (and how) possible, to have application specific scaling for their windows?

Possible solution

I am no expert on X, multiple displays or tunneling, but: Maybe this is possible through the use of a second xserver running that has this solution applied: Can X11 scale to virtual resoltions on HiDPI/Retina screens the way OS X does? and somehow the resulting windows are being tunneled to the main screen? If that was possible, one could write a wrapper so non hidpi applications do not kill the user's eyes.

Best Answer

The following could provide a temporary solution.

https://github.com/rubo77/set_resolution.py

List the applications you wish to scale and the resolution you wish to scale them to. There is a second or so lag when switching applications, but it's the best I've got until developers start accommodating HiDPi screens by default.

Related Solutions

Keep applications running across X sessions

You have to leave the original X server running. You can start another X server on another tty. So, on a typical system, do ctrl+alt+f1, then log in and run startx -- :1. You should end up with another X session on reachable by ctrl+alt+f8.

Any number of X servers can be started by changing the number after the colon; if you use a number larger than 12, you can use chvt to change to it instead of the key combo.

If you want, you can setup special .xinitrc files that start different desktop environments. So you might have a .xinitrc-kde that starts a KDE session. In that file, you'd have something like exec startkde. And you'd start X like by doing startx ./.xinitrc-kde -- :1.

If you plan on running Firefox on both the sessions, there may be some issues. Look into the "no-remote" and "ProfileManager" command line options for Firefox.

How to achieve higher resolution than physical resolution of an LCD

In short, you want something like

xrandr --output LVDS --scale 1.28x1.28

(replacing LVDS with the desired output name, as seen in the output of running xrandr by itself).

Give it a try. Some sites said that this doesn't work on some systems that are using KMS (kernel mode setting); if so, that's a bug that's hopefully fixed. See these links for some more info on using xrandr to scale a screen like this: