Issue with implementing a tcell.Tty wrapping a websocket

[tjhowse]

This isn't an issue with tcell, per se, but I thought this might be a good place to ask.

I'm working on a personal project that provides an interface to a tcell (tview, actually) application via websockets to xterm.js in a browser. I am hitting an issue stemming from a lack of understanding of how TTY screen buffer contents translate to printable characters. I have boiled down my implementation to a minimum demonstration here: https://github.com/tjhowse/websockettty

This demonstration excludes all the websocket stuff and just tries to print the screenbuffer to the local terminal.

Expectation:

╔═══Hi═══╗
║        ║
║        ║
║        ║
║        ║
║        ║
║        ║
║        ║
║        ║
╚════════╝

Reality:

??????????
??????????
??????????
??????????
??????????
??????????
??????????
??????????
??????????
??????????

Any help would be fantastic.

Cheers,
tjhowse.

[tjhowse]

OK. I think I've got to the bottom of this.

func withWebsocketTty(initScreen bool) {
	// Make a WebsocketTty object
	tty := websockettty.WebsocketTty{}
	// Look up a terminfo definition should work
	ti, err := tcell.LookupTerminfo("tmux")
	if err != nil {
		log.Fatal(err)
	}
	// Build a tcell.Screen object
	screen, err := tcell.NewTerminfoScreenFromTtyTerminfo(&tty, ti)
	if err != nil {
		log.Fatal(err)
	}
	if initScreen {
		screen.Init()
	}
	// if !screen.CanDisplay('=', false) {
	// 	log.Fatal("Your terminal cannot display the equals sign")
	// }
	// Build a tview application
	app := tview.NewApplication()
	box := tview.NewBox().SetBorder(true).SetTitle("Hi")
	app.SetRoot(box, true)

	// Start the application running in the background.
	app.SetScreen(screen)
	go app.Run()
	// Crudely give it some time to draw.
	time.Sleep(time.Millisecond * 100)

	fmt.Printf("%s", tty.Screenbuffer)
}

This function only prints the expected output if initScreen is true. The docs on SetScreen says Init() need not be called on a screen before passing it to the app: https://github.com/rivo/tview/blob/master/application.go#L172

I'll raise an issue on the tview repo.

Cheers,
tjhowse.