Unexpected blank area

[GavinGuan24]

call stty -a, show like that 23 rows; 97 columns;

Step 1: I call

screen.SetContent(0, 95, '中', nil, tcell.defaultStyle)
screen.Show()

that's working.

Step 2: I call

screen.SetContent(0, 95, 't', nil, tcell.defaultStyle)
screen.SetContent(0, 96, 'k', nil, tcell.defaultStyle)
screen.Show()

that's working with a bug. the t disappeared !!!
I think you have a bug with handling Double wide character.
It happens on the right edge of the screen.

for avoiding this, I have to call screen.Clear();screen.Show().
This will cause the screen to flicker.
I can't accept this thing.

[gdamore]

It looks like the problem is that the final column isn't handled properly when there are an odd number of columns and using wide characters. Does this problem occur when using a terminal width of 96 or 98 instead of 97?

[gdamore]

I'm actually thinking that I may have made a bogus assumption that wide characters will only occur in an even numbered cell.

[gdamore]

What terminal are you using?

[gdamore]

I've tried to reproduce this unsuccessfully. This was using go in a Windows terminal on both Windows and on WSL (Linux, but still using the Windows terminal).

Here's the code I used:

[gdamore]

package main

import (
	"time"

	"github.com/gdamore/tcell"
)

func main() {

	s, e := tcell.NewScreen()
	if e != nil {
		panic(e.Error())
	}

	if e = s.Init(); e != nil {
		panic(e.Error())
	}

	s.SetStyle(tcell.StyleDefault.
		Foreground(tcell.ColorBlack).
		Background(tcell.ColorWhite))
	s.Clear()

	s.SetContent(0, 0, 'A', nil, tcell.StyleDefault)
	s.SetContent(95, 0, '中', nil, tcell.StyleDefault)
	s.Show()

	time.Sleep(time.Second * 2)
	s.SetContent(95, 0, 't', nil, tcell.StyleDefault)
	s.SetContent(96, 0, 'k', nil, tcell.StyleDefault)
	s.Show()
	time.Sleep(time.Second * 2)

	s.Fini()
}

[gdamore]

You'll note that you had several other bugs in your original post (X and Y mismatched, style settings incorrect, etc.)

I will also note that I tested in both conemu and Windows Terminal. One thing that is a little weird if you put a sleep between the emit of 't' and the emit of 'k' (and a Show() in there too), then conemu attempts to move the Chinese character one space to the right.

The Windows terminal does not properly display the chinese character at all, but instead places a Unicode place holder character there. But it does display the English characters fine, without any problems.

I suspect we're in a problematic area for handling wide characters in the terminals themselves, but without more information there's not much I can do to validate.

[GavinGuan24]

Thanks for your reply. I am so sorry to reply you now.
I'm a Chinese, not good at using English.
And I was coding a TUI frame on my Macbook Pro (early 2015) three months ago.
The product was running on Iterm 2, you can google Item2.

https://github.com/GavinGuan24/gofer
I have forced fix it on [bugfix 20190717], but this is not what I wanna see.

https://github.com/GavinGuan24/gofer/blob/master/gofer/rootView.go (line: 72 ~ 78)

There is enough space on the screen to display those content.
I also follow the logic of Tcell to set the content of each point.
I am not sure if it is Tcell's problem. But the BUG did happen.
I am sure that my code logic here is ok.
Because I checked my code for this bug many several times.

I will describe the process again. Let's say '0' is a pixel, '中' is two pixel.
screen size (1 row × 4 col )
Move '中' to right edge.

step 1
0000

step 2
a中b

step 3
0a中

step 4
00a>

on step 4, '00a>' is what I want to display.
Because you can't use one pixel to show two pixel width characters ('中').
But, in fact, what appears on the screen is '00_>'. ('_' is ASCII code 0x20. yeah, it's SPACE.)
it's a BUG. It happens at the right edge of the screen.
so, I have to check if the original content of the second to last pixel of each line is a double wide character.
And invoke Screen.Clear() and Screen.Show().
'sw' is the width of screen.

        for row := 0; row < sh; row++ {
            _, _, _, width := v.Screen.GetContent(sw-2, row)
            if width > 1 {
                v.Screen.Clear()
                v.Screen.Show()
            }
        }

I hope that my description is clear enough. 😅

You can reproduce this.

step 1
git clone Latest version code of github.com/GavinGuan24/gofer

And comment out these lines.
https://github.com/GavinGuan24/gofer/blob/master/gofer/rootView.go (line: 72 ~ 78)

step 2
edit line 9, Empty = ' ' to Empty = '-'
https://github.com/GavinGuan24/gofer/blob/master/gofer/rune.go

step 3
go run https://github.com/GavinGuan24/gofer/blob/master/demo/view_relationship_test/test.go
type d, move view1 to right edge of screen. you will see that bug.

by the way, Ctrl+q to quit.
'wsad' to move view1
'↑↓←→' to move view2