Use real terminal font size

[piranna]

Instead of have hardcoded values for the number of pixels of the font on screen, it's possible to get the real font size in pixels using the ws_xpixel and ws_ypixel values, between some other syscalls and tools, although they are poorly supported, but if they can be fetch, it's better to use the real values to do the calcs.

https://stackoverflow.com/questions/42936926/ws-xpixel-and-ws-ypixel

[GottZ]

that's a client sided syscall right? you won't be able to use that through ssh or mosh if I'm not mistaken.
if you are using this locally, wouldn't it be more reasonable to approach command line flags for dpi first?

[fathyb]

You can access it through SSH or Docker (with -t or --tty) as those programs create a virtual PTY on the server which proxies requests back to the client.

Carbonyl currently uses the same syscall ioctl(STDOUT, TIOCGWINSZ) to retrieve the number of rows and columns, we just ignore ws_xpixel and ws_ypixel.

carbonyl/src/output/size.rs

Line 9 in 6b906b0

if libc::ioctl(libc::STDOUT_FILENO, libc::TIOCGWINSZ, ptr.as_mut_ptr()) == 0 {

I should release both this and a --dpi flag this week with #28.

[piranna]

It seems my original idea was more related to chafa, but by the moment, current algorythm is fine :-)