term: add key_pressed, enable_echo

[kbkpbot]

Feature/Enhancement Request
#21826

// enable_echo enable/disable echo input characters
pub fn enable_echo(enable bool) 
// key_pressed gives back a single character, read from the standard input.
// It returns -1 on error or no character in non-blocking mode
pub fn key_pressed(blocking bool, echo bool) int 

TODO: add tests, but I don't know how ....

_{Huly®: V_0.6-21607}

[kbkpbot]

Example usage:

module main

import term
import time

fn main() {
        defer {
                term.enable_echo(true)
        }
        term.enable_echo(false)
        for {
                // non-blocking mode, no echo
                x := term.key_pressed(false, false)
                if x >= 0 {
                        println(x)
                }
                time.sleep(1 * time.millisecond)
        }
}

[spytheman]

I'm using this variation to test:

module main

import term
import time

fn main() {
	unbuffer_stdout()
	term.enable_echo(false)
	defer {
		term.enable_echo(true)
	}
	for {
		// non-blocking mode, with echo
		x := term.key_pressed(false, true)
		if x == 0 {
			break
		}
		if x > 0 {
			println(x)
		}
		time.sleep(16 * time.millisecond)
		print('\r${time.now()} | ')
	}
	println('done')
}

(pressing Ctrl-D exits the loop, without having to reset the terminal, which is needed if I stop it with Ctrl-C)

[kbkpbot]

I'm using this variation to test:

module main

import term
import time

fn main() {
	unbuffer_stdout()
	term.enable_echo(false)
	defer {
		term.enable_echo(true)
	}
	for {
		// non-blocking mode, with echo
		x := term.key_pressed(false, true)
		if x == 0 {
			break
		}
		if x > 0 {
			println(x)
		}
		time.sleep(16 * time.millisecond)
		print('\r${time.now()} | ')
	}
	println('done')
}

(pressing Ctrl-D exits the loop, without having to reset the terminal, which is needed if I stop it with Ctrl-C)

Thanks, add it to examples

[spytheman]

It seems that the keycodes that are used for F1..F12 + arrows + home/end keys, are different than the ones that terminals on linux/macos use 🤔 .

[spytheman]

examples/term.ui/event_viewer.v (and term.ui) already does a good job of providing an uniform API to user programs, when it comes to keyboard events/key sym codes.

Unfortunately it is more of a framework (with callbacks), not a library 🤔 .