Add Horizontal and Vertical Content Alignment Options to ScrollContainer

[KnifeXRage]

Added two new properties to ScrollContainer:

• horizontal_content_align
• vertical_content_align

Allows ScrollContainer content to be aligned left/center/right and top/center/bottom from Inspector or using GDScript.
And also updated Documentation in doc/classes/ScrollContainer.xml.

Here is a demo video of ScrollContainer Content Alignment Feature:

Scroll.Container.Content.Alignment.Feature.mp4

[AThousandShips]

Thanks for opening a pull request!

Feature pull requests should be associated to a feature proposal to justify the need for implementing the feature in Godot core. Please open a proposal on the Godot proposals repository (and link to this pull request in the proposal's body).

[KnifeXRage]

Thank you for the guidance! This is my first pull request, so I really appreciate your help. I will create a feature proposal on the Godot proposals repository and link this pull request in the proposal.

[KoBeWi]

How is this different from using size flags?

godot.windows.editor.dev.x86_64_LfJ6lo4WnG.mp4

[KnifeXRage]

Thanks for asking! Size flags control how a child expands or fills space, but they don’t let you explicitly align content inside a ScrollContainer.

With the proposed horizontal_content_align and vertical_content_align properties, developers can directly position content (center, right, bottom, etc.) without adding extra nodes or writing custom scripts and it can be directly controlled using gdscript, which makes layouts simpler and more intuitive.

[KoBeWi]

But it doesn't need any "extra" nodes. The ScrollContainer already requires one content node (BoxContainer, GridContainer etc.), and that node is the subject to size flags. You even have one in your video, I replicated that layout. You can set the alignment from GDScript using set_anchors_and_offsets_preset().

[KnifeXRage]

Yes, you are right, but i just added this feature for easier use. it's easy to find and use from the inspector panel.

[AThousandShips]

Should still use the enum type, for both

[AThousandShips]

Suggested change

	H_ALIGN_LEFT = 0,
	H_ALIGN_CENTER = 1,
	H_ALIGN_RIGHT = 2,
	CONTENT_H_ALIGN_LEFT,
	CONTENT_H_ALIGN_CENTER,
	CONTENT_H_ALIGN_RIGHT,

And both should be registered with VARIANT_ENUM_CAST below

[AThousandShips]

Suggested change

	V_ALIGN_TOP = 0,
	V_ALIGN_CENTER = 1,
	V_ALIGN_BOTTOM = 2,
	CONTENT_V_ALIGN_TOP,
	CONTENT_V_ALIGN_CENTER,
	CONTENT_V_ALIGN_BOTTOM,

[AThousandShips]

Should still be registered using the correct type, with BIND_ENUM_CONSTANT like below, and below the other ones

[KnifeXRage]

I tried it but it's not working. And engine compilation fails. But this way it works properly. But I will try again.

[AThousandShips]

It should work if done correctly

[AThousandShips]

This file needs to be restored from all the unnecessary changes