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3731 :: The terminal module and reading the non-alphanumeric key presses

• bronikowski (orginal) [2018-04-07T20:45:45+02:00] view original

  Hello,

  another weekend with a free time, so I'm playing around with Nim. I decided I'll try to write a little terminal plaything but after having a good luck with the fact that terminal implements almost everything I wanted I got stuck on getch() — as I guessed it only picks up the alphanumeric characters. ESC or F1 or → all produce 7 when I ord() the return value.

  Maybe I'm missing something? Like switching stdout to raw?

  import terminal
  
  setForegroundColor(stdout, ForegroundColor.fgRed)
  setStyle(stdout, {Style.styleBlink, Style.styleBright})
  var c = getch()
  echo(c, ord(c))
  Run

  Any pointers would be welcomed!

  (Or maybe I should go directly to ncurses?)

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• Udiknedormin (orginal) [2018-04-08T11:47:50+02:00] view original

  But that's just how the terminal works. For me, it returns:

  • ESC: 27
  • F1: 27, then 79, then 80 (THREE chars per one keydown)
  • →: 27, then 91, then 67

  The problem's not with the lib. Go ahead try it in C, you should get the same results.

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• bronikowski (orginal) [2018-04-09T14:55:04+02:00] view original

  Thanks Udikendormn, that makes sense. So, what would the solution be? If F1 puts that sequence of three values into stdin and getch() plucks one (and blocks, so I can't call it one after another). Would catching the start of a sequence and just reading next bytes out of stdin work?

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• h42 (orginal) [2018-04-09T16:08:42+02:00] view original

  The easiest thing to do is do a read on stdin with a buffer big enough to hold the longest sequence. I only do this sort of thing on posix systems so posix read with a size of 6 should cover all function key escape sequences. The problem is bit bigger if you want a general solution. Different terminals use different key strokes. Linux console uses different seqs than xterm. xterm uses slightly different sequences than other xterms like gnome-terminal. The easiest solution is to use ncurses. If you don't want to do that, you can parse the output of the program "infocmp" to get the sequences for any terminal you want which is usually the value in the environment variable "TERM".

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• bronikowski (orginal) [2018-04-09T19:06:52+02:00] view original

  Yeah, h24, I'll probably get ncurses, I bet I'll get stuck on another solved issue if I'll stick to trying to make RAW work for me.

  Thanks for your help!

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• shashlick (orginal) [2018-04-10T06:40:51+02:00] view original

  Check out the console snippet editor snip I did a few months ago. It's far from perfect but works well enough.

  The code is mainly in key.nim and keymap.nim.

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