The "clear current line and reprint" doesn't work with long suffix

[gbouv]

Easy repro:

func main() {
	suffix := "    super long string super long string super long string super long string super long string super long string super long string super long string super long string super long string super long string super long string super long string super long string super long string "
	spin := spinner.New(spinner.CharSets[11], 100*time.Millisecond, spinner.WithSuffix(suffix))
	spin.Start()
	time.Sleep(2 * time.Second)
	spin.Stop()
}

Other side effect: we can't have multi line suffix (string with \n)

I think rather than clearing current line only, it should mark the location of the spinner and then erase everything between the marked location and current location.

[gbouv]

This can be "easily" fixed with the following spinner:

spin := spinner.New(spinner.CharSets[11], 100*time.Millisecond, spinner.WithSuffix(suffix))
spin.PreUpdate = func(s *spinner.Spinner) {
    fmt.Print("\0337\033[J") // save cursor position and erase everything until end of screen
}
spin.PostUpdate = func(s *spinner.Spinner) {
    fmt.Print("\0338")  // restore cursor position
}

But I would have expected the spinner to handle it by itself

Also, the downside of doing \033[J in the PreUpdate is that we're clearing current line twice, which is unnecessary

[gbouv]

In fact the above "hack" doesn't even work when we start printing at the bottom of the terminal because scrolling messes up with the saved position.
So, I had to implement the actual fix of computing in advance how many lines will be needed to print the entire "spinner + suffix" string, and clearing this exact number of lines on every update in the PreUpdate function. It seems to be the only working solution

[briandowns]

Care to share your solution or submit a PR?

[gbouv]

Yup @briandowns I'll submit a PR and tag you on it in the next few days when I have a bit more bandwidth 👍

[gbouv]

@briandowns sorry it took so long, but the PR is up and ready for review: #146
Let me know what you think