fix: issue 3935 handle F13-F24

[ovidiu-ionescu]

Fixes: keys F13-F24 are not passed through on a PC122 keyboard issue 3935

[wez]

Thanks for this! For the sake of completeness, since I don't have a device where I can test this, could you also take a look at the kitty keyboard encoding for these keys?

There's some out-commented relevant code over here:

wezterm/wezterm-input-types/src/lib.rs

Lines 1307 to 1322 in 69bb69b

	/*
	F21 => 57384,
	F22 => 57385,
	F23 => 57386,
	F24 => 57387,
	F25 => 57388,
	F26 => 57389,
	F27 => 57390,
	F28 => 57391,
	F29 => 57392,
	F30 => 57393,
	F31 => 57394,
	F32 => 57395,
	F33 => 57396,
	F34 => 57397,
	*/

that may also require some plumbing for higher numbered F-keys over here:

wezterm/wezterm-input-types/src/lib.rs

Line 1009 in 69bb69b

F20,

and here:

wezterm/wezterm-input-types/src/lib.rs

Line 742 in 69bb69b

F20,

and here:

wezterm/wezterm-input-types/src/lib.rs

Lines 1856 to 1869 in 69bb69b

	let intro = match *n {
	1 => "\x1b[11",
	2 => "\x1b[12",
	3 => "\x1b[13",
	4 => "\x1b[14",
	5 => "\x1b[15",
	6 => "\x1b[17",
	7 => "\x1b[18",
	8 => "\x1b[19",
	9 => "\x1b[20",
	10 => "\x1b[21",
	11 => "\x1b[23",
	12 => "\x1b[24",
	_ => unreachable!(),

Testing methodology should be something like:

• Spawn a wezterm with kitty keyboard enabled: wezterm -n --config enable_kitty_keyboard=true --config disable_default_key_bindings=true
• In a shell in there, run printf '\e[=31u' ; cat
• Try pressing those extended F keys; you should see very large numbers like 57397 for F34
• https://github.com/kovidgoyal/kitty/blob/master/docs/keyboard-protocol.rst#functional-key-definitions has more details on the protocol itself

[ovidiu-ionescu]

Sure, will do. My keyboard only has 24 Function keys labelled as such. Not sure if the extra 10 keys on the left are supposed to be the F25-F34 ones.

[ovidiu-ionescu]

I can make wezterm send the kitty codes for F13-F24 but neovim does not seem to enter CSI mode and does not react to them. Is there a way to diagnose the dialog establishing the mode between neovim and wezterm?

[wez]

You can use https://wezfurlong.org/wezterm/config/lua/config/debug_key_events.html to have wezterm show what it is sending to the program in the terminal, which may be helpful

[ovidiu-ionescu]

I think I found a problem in neovim, I found the place in the code where it ignores the F13 and higher kitty codes send by wezterm.

Also collected a backtrace when wezterm crashed while doing this.

[zeertzjq]

I don't think the escape sequences produced in this PR are correct.

https://sw.kovidgoyal.net/kitty/keyboard-protocol/ lists:

Name	CSI	Name	CSI
F13	57376 u	F14	57377 u
F15	57378 u	F16	57379 u
F17	57380 u	F18	57381 u
F19	57382 u	F20	57383 u
F21	57384 u	F22	57385 u
F23	57386 u	F24	57387 u

But the format used in this PR is {intro};{modifiers}{event_type}~, which ends with ~, not u.

[zeertzjq]

This is still incorrect, as F1-F12 should end with ~, so that most terminal programs that don't interpret characters in Private User Area can still recognize them.

I think it should be something like this:

            Function(n) if *n < 25 => {
                // The spec says that kitty prefers an SS3 form for F1-F4,
                // but then has some variance in the encoding and cites a
                // compatibility issue with a cursor position report.
                // Since it allows reporting these all unambiguously with
                // the same general scheme, that is what we're using here.
                let intro = match *n {
                    1 => "\x1b[11",
                    2 => "\x1b[12",
                    3 => "\x1b[13",
                    4 => "\x1b[14",
                    5 => "\x1b[15",
                    6 => "\x1b[17",
                    7 => "\x1b[18",
                    8 => "\x1b[19",
                    9 => "\x1b[20",
                    10 => "\x1b[21",
                    11 => "\x1b[23",
                    12 => "\x1b[24",
                    13 => "\x1b[57376",
                    14 => "\x1b[57377",
                    15 => "\x1b[57378",
                    16 => "\x1b[57379",
                    17 => "\x1b[57380",
                    18 => "\x1b[57381",
                    19 => "\x1b[57382",
                    20 => "\x1b[57383",
                    21 => "\x1b[57384",
                    22 => "\x1b[57385",
                    23 => "\x1b[57386",
                    24 => "\x1b[57387",
                    _ => unreachable!(),
                };

                let c = match *n {
                    1..=12 => '~',
                    _ => 'u',
                };

                format!("{intro};{modifiers}{event_type}{c}")
            }

[ovidiu-ionescu]

This is still incorrect, as F1-F12 should end with ~, so that most terminal programs that don't interpret characters in Private User Area can still recognize them.

You are right; I did actually figure that out myself before reading your comment and my fix is quite similar.

[ovidiu-ionescu]

@wez neovim seems to work Ok for me after the last commit.
Is there anything else you want done in this PR?

[wez]

Thanks!