Is there a way to have an `item` in a lazy column ...

# compose

[Adib Faramarzi]

Is there a way to have an item in a lazy column that fills the rest of the screen with its height? (.fillMaxHeight does not work).

[Filip Wiesner]

There is no such thing as "rest of the screen" in scrollable layout. In scrollable column the height constraint is inifinite

[Adib Faramarzi]

What would be the solution for this then?

[Adib Faramarzi]

The height (the constrained height) is not infinite. That’s why the lazy column can recycle

[Filip Wiesner]

It is inifnite because one item can span across multiple screen heights and is "recycled" when it leaves the visible part of column.
The solution depends on your use case 😄

[Filip Wiesner]

The height (the constrained height) is not infinite. That’s why the lazy column can recycle

I see, you meant the constraint of the column. I was talking about constraint of the item.

[Adib Faramarzi]

Yes

[Adib Faramarzi]

I think some sort of layout modifier can be written

[Adib Faramarzi]

maybe, specifically for lazy column child

[Filip Wiesner]

I still don't understand your use case so I can't help you 🤷‍♂️

[Adib Faramarzi]

We’re having a page that includes two parts (one that fills about 200dp of the screen and one that has infinite amount of items)
the second part can be empty and the design for the empty layout is a box that fills the rest of the screen and says “no items”.

[Adib Faramarzi]

and the whole page is scrollable (so all items are inside a lazy column)

[Adib Faramarzi]

[Adib Faramarzi]

The right one is what I’m talking about. The “no items” part is an item itself.

[Filip Wiesner]

I guess that the most "easy to implement" way is to use LazyColumn only conditionally. Otherwise use normal column and use weight(1f) for the second element

[Adib Faramarzi]

yeah, it would be much easier with regular column and weight.

[Filip Wiesner]

if (isEmpty) Column { ... } else LazyColumn { ... }

[Filip Wiesner]

And reuse the same UI in both situations

[Adib Faramarzi]

I'm trying to find a more efficient solution

[Adib Faramarzi]

Since this recomposes the top part

[Filip Wiesner]

And does that actually change often? I thought you'll just display the screen with either empty content or with items.

[Zoltan Demant]

Couldnt you just calculate the first items height, and divide that by the lists total height, then use it with Modifier.fillparentMaxHeight(fraction = 1f - firstItemHeightFraction). That should fill the rest of the screen, I think; just make sure the list has Modifier.fillMaxSize set so that youre actually getting its entire height in the calculation.

[Filip Wiesner]

That could work but it might be hard to do it "correctly" without things like onGloballyPositioned(). But that's your decision to make.

[Zoltan Demant]

Desperate times require desperate measures, @Filip Wiesner 🥲 It will also break if more than 1 item is "at the front"; but I cant think of any other solution for something like this.

[Filip Wiesner]

Well, slower UI is better than fragile UI in my book 🤷‍♂️

[Afzal Najam]

Since this recomposes the top part

Don’t think that’d be a problem but even if it is, moveableContentOf in the latest alpha should alleviate that.

[Adib Faramarzi]

was not aware of that 👍

[Andrey Kulikov]

LazyColumn wraps the content height when there are not enough items to fill the maximum height. so you can wrap LazyColumn into one more Column and set weight on a second child, so it will fill the rest of the heigh not occupied by the LazyColumn