Fix case where h_separation might not work in Button

[Rindbee]

Fix #64140.
Bugsquad edit: Fixes #64371

Before	After

Split from #59340.

There are still issues with the drawing and will be fixed in another PR.

Edit:
This patch mainly solves two things:

1. The typo of h_separation;
2. Negative values of h_separation will be treated as 0 when used, to prevent the button's minimum width from being reduced by h_separation.

[KoBeWi]

Looks good.

[KoBeWi]

You added me as co-author (GitHub does this automatically when you accept a suggestion).

[Rindbee]

Sorry, h_separation should be ignored when expand_icon is enabled.

[KoBeWi]

Uh why should it be ignored? It's just a space between icon and text. If you expand icon and resize to 0, it's still there and separation should take effect. The previous behavior was alright.

[Rindbee]

For Button-derived classes with internal elements, CheckBox, CheckButton, OptionButton, may appear to be twice as long (the icon is hidden).

Of course, they behave inconsistently, and it's not clear to me which one to use as a standard.

[KoBeWi]

Ah seems like CheckBox etc. apply the separation twice for their own icon.

In this case ignoring separation makes sense.

But there is still no reason to ignore it in Button. You could either add a virtual method that tells whether this should be ignored or, more simple but not much used in the codebase, some protected bool property.

Seems like more changes are needed

[Rindbee]

I seem to be getting more and more deviated from the original intention. Now I only fix typo and restrict h_separation from being negative.

When h_separation is non-negative, it should look the same as in alpha13

[KoBeWi]

OptionButton minimum size seems broken:

CheckBox center alignment makes the text go into separation area:

The worst part is that it's more to the left than Left alignment. CheckButton has similar problem.

[Rindbee]

OptionButton minimum size seems broken.

I guess it has something to do with fit_to_longest_item, switching expand_icon doesn't update the cache.
Steps to reproduce it:

1. Make h_separation larger, such as 200;
2. Let fit_to_longest_item be disabled and expand_icon be enabled;
3. Then enable fit_to_longest_item;
4. Disable expand_icon.

Currently, changes in the factors that affect get_minimum_size do not update the OptionButton cache. I think it's better to disable fit_to_longest_item first and then test, finally, solve the problem of fit_to_longest_item cache update in other PRs.

CheckBox center alignment makes the text go into separation area. The worst part is that it's more to the left than Left alignment. CheckButton has similar problem.

This should be a drawing issue, which will be resolved in #64351, where there is a set of comparison images with alpha13.

[KoBeWi]

I assume #64218 (comment) is addressed in #64351?

[Rindbee]

I assume #64218 (comment) is addressed in #64351?

I guess no, both patches are trying to get back to alpha13. Except that a negative h_separation is treated as 0, and limits the extent to which the text/icon can be drawn. These changes between alpha13 should be intuitively found from comparing pngs in #64351.

This issue in #64218 (comment) also exists in alpha13.

I'm a little unclear on what exactly it should look like. So had to use alpha13 as a reference. If there is something wrong in alpha13, I will fix it later. I'm a little concerned about over-modification causing other regressions.

It might be better to figure out what it should look like first.

1. internal element (i_icon)
   1.1 existence
2. custom elements
   2.1. custom icon (icon)
   2.1.1. existence
   2.1.2. expand_icon
   2.1.3. icon_alignment
   2.2. custom text (text)
   2.2.1. existence
   2.2.2. clip_text
   2.2.3. text alignment
   2.3. separation between custom elements (s1)
3. separation between internal element and custom elements (s0)

The above will directly and indirectly affect the minimum size.
In alpha13, if there are only icon and i_icon, s0 is ignored. It's a little different when if i_icon, icon, text all exists.

The documentation's description and the actual drawing in alpha13 are inconsistent.

The actual drawing in alpha13 and your suggestions are inconsistent.

I haven't looked into the button's design criteria, so I'm a little confused.

However, this patch is intended to fix typo to get it back to a slightly better state.

[akien-mga]

Thanks!