Implement center window function

[Jordyfel]

Following the discussion in #65843, implements a center() function in Window.

Closes godotengine/godot-proposals#5232.

Took inspiration (copied and modified) from the implementation of Window.popup_centered().

Edit: Confused myself from following the popup logic... every non-embedded window will now center itself on it's own screen, while embedded windows will center themselves on the parent window.

Quick and dirty test project (test with embed_subwindows on and off):
empty_project.zip

[Jordyfel]

This CI fail might be because I manually moved the doc in the XML after running --doctool. Should I not do that?

[akien-mga]

Indeed you should keep it where it's generated, it's alphabetically ordered.

[raulsntos]

I share the concerns from #65843 (comment) in the original PR. I think "center" for the method name is confusing since it can be interpreted as a noun. Can we consider calling it move_to_center or center_to_screen instead?

[Jordyfel]

In my opinion it's clear enough, since it's a name of a method. Consistent with popup().

[Sauermann]

Implementation looks good to me.

The method has problems in the embedded case, when used within a window that has content_scale_stretch = Window.CONTENT_SCALE_STRETCH_INTEGER.
MRP: empty_project.zip

WindowCenter.mp4

I'm not sure, if this is a limitation of CONTENT_SCALE_STRETCH_INTEGER which was introduced in #75784 or if this can/should be worked around.

[Jordyfel]

This problem with integer scaling happens only when the screen is reduced in size. The code in that PR doesn't allow the scale factor to be less than 1, which makes sense. I'm not sure this case needs handling, since doing this would be almost always undesired anyway.

If anything, it would be sensible to set the minimum size of the screen to the original viewport size in integer scaling mode.

[Sauermann]

If anything, it would be sensible to set the minimum size of the screen to the original viewport size in integer scaling mode.

I had the same thought. So the mentioned problematic case can be ignored here.

Also please squash your commits together as explained in the docs:
https://docs.godotengine.org/en/latest/contributing/workflow/pr_workflow.html#the-interactive-rebase

[Jordyfel]

Done, also renamed to move_to_center().

[Sauermann]

Implementation looks good. Tested also functionality.

[akien-mga]

Looks good.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[CsloudX]

Why I can't found move_to_center in Window class(4.2 beta1)?