Add a component to enable/disable interactions on a UI node

[Exanc]

Objective

Project goal: Component type for enabling/disabling UI widget interactions (allow inactive buttons, etc…)

Solution

The Interactivity component.
It stores a state describing whether an Interactive Node can be interacted with or not.

An interactive node can be described as an entity containing both the Node and Interaction components.

The Interactivity component can be defined with the following properties:

#[derive(Component, ...)]
#[require(Node, Interaction)]
pub enum Interactivity {
	Enabled,
	Disabled,
}

It is used by the ui_focus_system to determine whether an interactive node should have it's Interaction component updated when an interaction does occur. Furthermore, the assertion should be made that a "disabled" entity will always have it's Interaction component set to Interaction::None.

It can also be used by secondary systems to, for example, change the visual appearance of a UI node, or to decide whether or not to use FocusPolicy::Block.

Testing

Not yet

Migration Guide

Migrations are not necessary as the absence of the Interactivity component is interpreted as the component being enabled.

[Exanc]

There is still a missing, point: when an Interactivity component is changed, where should it be detected ? ui_focus_system or another on ?
Should we instantly change the interaction to None or let the current one finish ?

[alice-i-cecile]

#15597 will be removing ui_focus_system and Interaction. I would integrate with bevy_picking and try and use observers where possible.

[Exanc]

@alice-i-cecile did not notice this change, there's a lot of info to keep up with 😅

[Exanc]

Should we instantly change the interaction to None or let the current one finish ?

The interaction states of components will instantly be changed, to keep up with the assertions made.