padding reveals an area without background color

[tcurdt]

Unfortunately setting a padding reveals an area where I cannot set a background color.
Here the left and right padding is just white instead of black.

Why isn't the background color being used?

Originally posted by @tcurdt in #831 (comment)

[rivo]

I tried to reproduce this but couldn't. Please post a small code snippet that reproduces this issue.

[digitallyserviced]

@tcurdt Sometimes this can be caused by certain containers not having their base Box primitive's dontClear value set right.

I have had to hack a method to allow this to be modified so that I could ensure that existing, and any custom primitives I developed I could make sure that it cleared the background or not...

My fork which has the method to set this property...
https://github.com/digitallyserviced/tview/blob/611a26b9bad195005135a6ce0215280c68d57903/box.go#L136

The current part of the draw function that uses this when filling backgrounds in Box primitive...

why this property is not modifiable externally I am not sure, but is very useful when developing custom primitives

    background := def.Background(b.backgroundColor).Reverse(b.reverse)
	if !b.dontClear {
		for y := b.y; y < b.y+b.height; y++ {
			for x := b.x; x < b.x+b.width; x++ {
				screen.SetContent(x, y, ' ', nil, background)
			}
		}
	}

[tcurdt]

Here is a snippet from the code.

...
	layoutCol2 := tview.NewFlex().
		SetDirection(tview.FlexRow).
		AddItem(identificationTextview, 3, 0, false).
		AddItem(valueInput, 1, 0, false).
		AddItem(detailsTextview, 6, 0, false)
	layoutCol2.SetBorder(true)
	layoutCol2.SetBorderPadding(0, 0, 1, 1)

...

	layoutControl := tview.NewFlex().
		SetDirection(tview.FlexColumn).
		AddItem(layoutCol1, 50, 0, false).
		AddItem(layoutCol2, 23, 0, false).
		AddItem(layoutCol3, 0, 1, false).
		AddItem(layoutCol4, 40, 0, false)

...

Let me know if that already helps.
Otherwise I need to try and extract the problem somehow.

[digitallyserviced]

@tcurdt ya your code doesnt really help, because i am already pretty sure of the problem... you need to make dontClear available to your code because Flex is one of the primitives that defines dontClear as true

I do not agree with the idea in the comment for NewFlex stating that you need to define nil flex areas with an empty box to set a bG color... specifically because of what you have experienced without having anything to do with nil flex areas...

// Note that Box, the superclass of Flex, will not clear its contents so that
// any nil flex items will leave their background unchanged. To clear a Flex's
// background before any items are drawn, set it to a box with the desired
// color:
//
func NewFlex() *Flex {
    f := &Flex{
        direction: FlexColumn,
    }
    f.Box = NewBox()
    f.Box.dontClear = true
    return f
}

I already provided the link to what needs to be added to make this modifiable from outside tview
https://github.com/digitallyserviced/tview/blob/611a26b9bad195005135a6ce0215280c68d57903/box.go#L136C1-L139C2

[digitallyserviced]

@tcurdt @rivo
#860 should resolve this... it definitely should be available outside regardless... it is not just here it becomes an issue. This is why it is included in my fork.

@tcurdt
if this PR is merged you would then do something like..

	layoutCol2 := tview.NewFlex().
		SetDirection(tview.FlexRow).
		AddItem(identificationTextview, 3, 0, false).
		AddItem(valueInput, 1, 0, false).
		AddItem(detailsTextview, 6, 0, false)
	layoutCol2.SetBorder(true)
	layoutCol2.SetBorderPadding(0, 0, 1, 1)

    // dontClear disables bg wipes, so set to false for this padding on a flex
    // previous comments show where this is set to `true`
    layoutCol2.SetDontClear(false)

[tcurdt]

@digitallyserviced So far it feels a little unintuitive having to bother with this though.

[digitallyserviced]

@tcurdt

So far it feels a little unintuitive having to bother with this though.

i agree but there are a lot of things in life that are unintitive or bothersome... and you're still alive