Support width/height: 'auto'

[felixmariotto]

Currently, either a Block has a width, either its width can be computed from its children width (same for height).

It would be a great addition to support width/height: 'auto', so that a component takes all the width (or height) it can in its parent component.

It should be done by BoxComponent.

[enijar]

I've been investigating how to implement this feature. In my experiments, I game across this library, which uses this library to do most of the layout work.

I don't think adding that as a dependency would be the best route though as its lots of bloat. My thoughts are to do the following:

Store all geometry bounding boxes (in an in-memory cache) in a tree structure, e.g.

       A
    __||__
    ||  ||
    B    C
 __||__
 ||  ||
 D    E

And calculate the children's width/height based on this tree structure each frame.

What do you think about this approach? I don't think it will involve a large amount of changes to the existing code to implement.

[felixmariotto]

Hi @enijar, thanks for investigating this issue.
I'm not sure I understand well your proposal.

In three-mesh-ui that's the parents that compute the children position because the children dimension is supposed to be known in advance. It's happening here. With the proposed new feature, I suppose the parent would have to decide of the children (with auto) dimension at the same time, and store these dimension values so that when the layout update cascades the children can resize themselves.

You may have noticed that when a layoutUpdate is triggered it is fired from the highest UI component of a component tree and cascade through the children. So when .getWidth and .getHeight are called here you could assume that if the component has a parent, the parent was able to pre-compute the children dimension.

Is it something similar that you have in mind ?

[enijar]

@felixmariotto let me pull together a WIP demo of what I'm proposing, and I can share it on a CSB link before making a PR.

[felixmariotto]

Or you can just file a PR as draft no worries