Fix Wide Character's width caculation in TextGrid

[typenoob]

Description:

Simply use https://github.com/mattn/go-runewidth to caculate wide char's widith in TextGrid.

Fixes #6099

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[andydotxyz]

Thanks for the fix. I don't think go.mod is up to date though, as the new dependency is listed as indirect.
Also you'll have to use an older version (the .17) to get a version compatible with our current Go version support.

[typenoob]

Sorry, I'm not very experienced in go package management. It has been fixed now.

[andydotxyz]

Sorry, I'm not very experienced in go package management. It has been fixed now.

In general "go mod tidy" fixes it - but in the situation of libraries requiring higher Go versions it does get more complicated.

[andydotxyz]

Sorry for the additional step, but TextGrid was just updated to not draw the underline as a separate object, so this is now conflicting.
Please push a new commit that merges develop and resolves the conflict.

[typenoob]

Done @andydotxyz

But there's one more thing I'm concerned. The width of textGrid returned by Size() is also wrong in Wide Char case.

package main

import (
	"fmt"

	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/widget"
)

func main() {
	a := app.New()
	w := a.NewWindow("Hello World")

	l := widget.NewLabel("一二三")
	t := widget.NewTextGridFromString("一二三")
	w.SetContent(container.NewHBox(
		l, t,
	))
	fmt.Printf("Label width is correct as %.1f, but textgrid width is wrong as %.1f",
		l.Size().Width, t.Size().Width)
	// Label width is correct as 58.0, but textgrid width is wrong as 24.0
	w.ShowAndRun()
}

And I can't figure out a clean way to fix, because currently all cells in the TextGrid are constrained to have the same size.

type textGridContent struct {
	BaseWidget
	text *TextGrid

	rows     int
	cellSize fyne.Size

	visible []fyne.CanvasObject
}

I'd like to make a seperate PR, what do you think?

[andydotxyz]

For performance all cells are the same size as you say.
I think you'll need to look at a "stride" approach - so if runeWidth == 2 then the item is painted but the cell after it is empty, before continuing as normal with an offset 1 cell later. (see how tab works for a similar algorithm).

[coveralls]

coverage: 60.808% (+0.01%) from 60.798%
when pulling cad6121 on typenoob:fix-wcwidth
into 465174c on fyne-io:develop.

[typenoob]

I think it's ready now.

[andydotxyz]

Thanks for this