Incorrect rendering of Emojis with Zero-Width-Join characters

[bcongdon]

It seems that some emojis sequences with zero-width-join runes are unable to be rendered correctly.

For example, with the List view:

package main

import (
	"github.com/rivo/tview"
)

func main() {
	app := tview.NewApplication()
	list := tview.NewList().
		AddItem("👩‍🍳", "Some explanatory text", 'a', nil).
		AddItem("👨‍👨‍👧", "Some explanatory text", 'a', nil).
		AddItem("🏳️‍🌈", "Some explanatory text", 'a', nil).
		AddItem("Quit", "Press to exit", 'q', func() {
			app.Stop()
		})
	if err := app.SetRoot(list, true).Run(); err != nil {
		panic(err)
	}
}

These emojis are rendered as their component emojis, instead of the full emoji sequence.

I've double checked that this is not a problem with my terminal emulator, as using the native fmt.Println function on these emojis renders them correctly.

fmt.Println("Emojis: 👩‍🍳 👨‍👨‍👧 🏳️‍🌈")

I've also noticed this behavior with the Table view, so I would suspect that this behavior is present in other views as well.

[rivo]

Thanks for spotting this. Approximately 90% of my work on tview is spent on making Unicode characters work properly. I thought I had solved it but there are obviously still issues.

I'll look into this. Might take me some time if I find there's no simple fix.

[rivo]

Looking into this some more, I found that I can't solve this without the help of tcell and runewidth (see referenced issues). Both of these packages seem to have issues with unicode sequences containing zero-width joiners.

Once support for ZWJs is implemented in these packages, I can fix it in tview as well. I hope that the maintainers will add support for ZWJ.

[rivo]

I just added support for zero-width joiners in tview. Note that the width of these characters will still be wrong. Once @mattn fixes mattn/go-runewidth#20, this should go away.

[bcongdon]

Thanks, I appreciate you fixing this!