Using rulerfmt to style the ruler

[joelim-work]

Description

I had an idea to take the existing design of statfmt and apply it to styling the ruler as well, because the current ruler option doesn't have any real support for customizing colors.

So I wrote up an implementation for a new rulerfmt option (roughly written with limited testing), which works like below:

• Placeholders for internal data
  • %a is the pressed keys
  • %p is the progress of file operations
  • %s is the number of files that are selected or being designated for cut/copied
  • %f shows is a filter is currently being applied
  • %i is the position of the cursor
  • %t is the number of files in the current directory
  • %d is the amount of free disk space remaining
• Placeholders for options
  • %{lf_<name>} for the value of options (e.g. %{lf_selmode})
  • %{lf_user_<name>} for the value of user-defined options (e.g. %{lf_user_foobar})
• Formatting for optional fields
  • Use | to divide the ruler into sections
  • Any section containing a failed placeholder substitution (blank result) is omitted

Implementation

Copy the following code into the ui.drawStatLine function (some other boilerplate code for adding a new option is required but not shown here):

// var reRulerSub = regexp.MustCompile(`%[apsfitd]|%\{([^}])+\}`)
if gOpts.rulerfmt != "" {
    opts := getOptsMap()
    rulerfmt := strings.ReplaceAll(gOpts.rulerfmt, "|", "\x1f")
    rulerfmt = reRulerSub.ReplaceAllStringFunc(rulerfmt, func(s string) string {
        result := ""
        switch s {
        case "%a":
            result = acc
        case "%p":
            result = strings.Join(progress, "  ")
        case "%s":
            result = strings.Join(selection, "  ")
        case "%f":
            if len(dir.filter) != 0 {
                result = "\033[34;7m F \033[0m"
            }
        case "%i":
            result = fmt.Sprint(ind)
        case "%t":
            result = fmt.Sprint(tot)
        case "%d":
            result = diskFree(dir.path)
        default:
            s = strings.TrimSuffix(strings.TrimPrefix(s, "%{"), "}")
            if val, ok := opts[s]; ok {
                result = formatRulerOpt(s, val)
            }
        }
        if result == "" {
            result = "\x00"
        }
        return result
    })
    ruler := ""
    for _, section := range strings.Split(rulerfmt, "\x1f") {
        if !strings.Contains(section, "\x00") {
            ruler += section
        }
    }
    ui.msgWin.printRight(ui.screen, 0, st, ruler)
    return
}

Example

lfrc configuration (adapted from #1347 (comment)):

set rulerfmt "%p  |%s  |\033[35m%i\033[0m/\033[36m%t\033[0m|  \033[34m%d\033[0m|  \033[32m%{lf_user_selected_size}\033[0m"

cmd on-select &{{
    s=$(find $fx -type f -maxdepth 1 -ls | awk '{total += $7} END {print total}' | numfmt --to=iec --format='%.2fB')
	lf -remote "send $id set user_selected_size $s"
}}

map <space> :toggle; on-select; down
map v :invert; on-select
map u :unselect; on-select

The value of rulerfmt can be a bit long, but it should be possible to build it in a ${{ ... }} shell block which calls lf -remote at the end to set the value.

Conclusion

This idea opens up more opportunities for customizing the ruler, especially the ability to apply styling and colors. I am not sure whether this will end up being merged, perhaps not since there is already a ruler option.

In any case, I didn't spend too long hacking this proof of concept up, as the main ideas were already implemented in the statfmt option, and the experience was fun anyway.

[gokcehan]

@joelim-work In general, I like the idea of introducing rulerfmt as it makes things more consistent with our options. ruler option is still relatively new (introduced in r29), so maybe a breaking change is still acceptable. If rulerfmt works in parallel with ruler, then we can also consider deprecating ruler for a few releases before removing it. So feel free to merge this if you like.

After rulerfmt, I think maybe the only inconsistency left would be to use the special separator | for promptfmt as well. I think maybe it could be introduced without any breaking changes. I'm not sure if there is a use case for it in promptfmt though.

[joelim-work]

@gokcehan Thanks for the feedback, I have submitted a PR #1386 which implements this option and deprecates the existing ruler option (it's still available for the time being).

I have thought about promptfmt too, but TBH I'm not sure if it's worth it because unlike the other cases there aren't really any 'optional' fields (you pretty much always have a username, hostname and current file). The only exception is the filter, but in my opinion this kind of information really belongs in the ruler, as you previously suggested in #667 (comment).