On a high DPI screen, lines in Xfig are very thin. Is it possible to scale the lines, or the entire Xfig UI?
Note that I don't want to scale the entire desktop. Other application UIs are legible on high DPI screens.
Perhaps a Wayland compositor can scale an individual window?
Method that I used in the end:
Run Xfig in its own desktop under TigerVNC server.
Connect to the VNC server with a VNC client that allows scaling.
To simplify the process, I created a tool to run arbitrary applications scaled up, Vncdesk. A simple command such as vncdesk 2 starts the server and connects a viewer. Closing the application or the viewer shuts down the VNC server:
An alternative could be running each application window in its own VNC viewer, which is the goal of experimental x11vnc -appscale.
I'm now using an Apple 32-inch "Pro Display XDR" monitor on a macOS system with Xquartz in full resolution (starting it with full-screen mode enabled using xrander -s 6016x3384), and Xfig is one of the few apps that so far still refuses all attempts to get even its menu fonts to resize relative to the screen resolution.
However a quick and dirty hack on macOS with Xquartz in full-screen full-res mode is to open Xfig in the top-left corner of the full-res screen, then switch back to macOS (by exiting full-screen mode), then back to Xquartz again but without changing the resolution with xrandr (i.e. just use the shortcut or menu to turn full-screen back on). Window decorations and window manager fonts will be scaled outrageously large of course, as now you can see just the top-left 1/4 of your Xquartz screen scaled to full-screen size, but you'll see Xfig clearly readable and usable in scaled mode.
This of course works for any application that is stuck in the dark ages of pixel-based layout and sizing.
Now if only macOS itself would run with the true full resolution of this display!
TL;DR Start another X server, change its resolution, use XFig in the new, lowish DPI environment.
If you don't mind switching between different X sessions, this works for me
xrandr$ xrandr Screen 0: minimum 320 x 200, current 2160 x 1440, maximum 16384 x 16384 eDP connected primary 2160x1440+0+0 (normal left inverted right x axis y axis) 296mm x 197mm 2160x1440 60.00*+ 1920x1200 60.00 1920x1080 60.00 1600x1200 60.00 1680x1050 60.00 1280x1024 60.00 1440x900 60.00 1280x800 60.00 1280x720 60.00 1024x768 60.00 800x600 60.00 640x480 60.00 HDMI-A-0 disconnected (normal left inverted right x axis y axis) DisplayPort-0 disconnected (normal left inverted right x axis y axis)and choose a lesser resolution.
$ echo 'xrandr -s 1600x1200' > ~/bin/startxfig $ echo 'xfig -option 1 ... -option n -geometry 1600x1200' >> ~/bin/startxfig $ chmod +x ~/bin/startxfig
$ startx xterm -e /home/username/bin/startxfig -- :2to have a full screen, reasonably scaled XFig. When you exit XFig, the
startxfig script returns and first the xterm and next the X server exit gracefully.