Add RowWrap layout

[ErikKalkoken]

Description:

Adds a new layout for dynamically arranging objects with same height in rows with wrapping.

In my opinion this layout solves a common layout problem and would be a good addition the Fyne toolkit. For example it would allow to dynamically arranging a set of filter chips in multiple rows:

I went with "RowWrap", because it arranges objects in rows and wraps them. This layout is similar to the existing GridWrap layout, so a similar name makes sense (i.e. it arranges in rows instead of a grid). But I am of course open to other suggestions.

Demo

Here is an example render:

Screencast.from.17.03.2025.15.39.08.webm

Code to reproduce the example:

package main

import (
	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/layout"
	"fyne.io/fyne/v2/widget"
)

func main() {
	a := app.New()
	w := a.NewWindow("RowWrap layout")
	c := container.New(
		layout.NewRowWrapLayout(),
		widget.NewButton("Alpha", nil),
		widget.NewButton("Bravo Charlie", nil),
		widget.NewButton("Delta", nil),
		widget.NewButton("Echo Foxtrott Golf Hotel", nil),
		widget.NewButton("India Juliet", nil),
		widget.NewButton("Kilo Limo Mike November", nil),
	)
	w.SetContent(c)
	w.Resize(fyne.NewSize(50, 50))
	w.ShowAndRun()
}

Checklist:

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

Where applicable:

• Public APIs match existing style and have Since: line.

[coveralls]

coverage: 62.303% (+0.04%) from 62.267%
when pulling 38a21aa on ErikKalkoken:add-rowwrap-layout
into a9d00e2 on fyne-io:develop.

[dweymouth]

For something with wrapping like this, (and Label/RichText etc with wrapping), the behavior needed IIRC is for the MinSize returned to depend on the current size of the object. If the object hasn't been Resized (IE its size is 0, 0), then it returns the MinSize as you currently calculate it. But if it has been resized to a width >= the min width, the MinSize height is based on how many rows it needs to lay things out at the current width. Otherwise, placing it as the child of another layout will always make it take up more height than needed.

Not sure how to do this with a layout though, given that they are stateless by design. I suppose in Layout you could remeber the size in the rowWrapLayout struct, and then reference it in MinSize

[andydotxyz]

Layouts don't have to be stateless (see Border), the thing they lack is any connection to the container they are laying out.

[dweymouth]

"Object visibility is supported" probably isn't needed, since all first-party layouts support object visibility, and as such it can just be assumed.

[Jacalz]

I really like the idea of this. Just left a few minor suggestions inline before I noticed it was a draft PR but I'm attaching them anyway :)

[Jacalz]

Fewer theme lookups is usually better:

Suggested change

	return &rowWrapLayout{
	horizontalPadding: theme.Padding(),
	verticalPadding: theme.Padding(),
	}
	padding := theme.Padding()
	return &rowWrapLayout{
	horizontalPadding: padding,
	verticalPadding: padding,
	}

[Jacalz]

Cleaner to just return directly:

Suggested change

	s := fyne.NewSize(width, rowHeight*float32(rows)+l.verticalPadding*float32(rows-1))
	return s
	return fyne.NewSize(width, rowHeight*float32(rows)+l.verticalPadding*float32(rows-1))

[Jacalz]

I think there is a fyne.Max() function you can use here instead.

[Jacalz]

This will add sizes of invisible objects as well. Is that expected?