flexbox-layout
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FlexboxLayout children not visible when width is unconstrained (such as within a horizontal recycler view)
- [X] I have searched existing issues and confirmed this is not a duplicate
Issues and steps to reproduce
When FlexboxLayout
's' width is unconstrained (i.e. the width MeasureSpec
mode is UNSPECIFIED
), its children views are not measured/laid out correctly, resulting in them being not visible.
This is relatively easy to replicate:
- Create a simple layout with a single horizontal
RecyclerView
- Add one item to the
RecyclerView
, whose view is aFlexboxLayout
such that:- its width and height are both set to
wrap_content
- it contains a
TextView
with arbitrary text in it
- its width and height are both set to
- Run the app and observe that the text is not visible
Expected behavior
The FlexboxLayout
child TextView
should be visible (i.e. allowed to be the width it wants).
Version of the flexbox library
- 2.0.1 and up
Notes
It seems the issue was introduced by this change: https://github.com/google/flexbox-layout/pull/521/files.
Looking at the current version of the corresponding code:
if (widthMode == View.MeasureSpec.EXACTLY) {
mainSize = widthSize;
} else {
mainSize = Math.min(largestMainSize, widthSize);
}
it seems to me that mainSize = Math.min(largestMainSize, widthSize);
should only apply when widthMode == View.MeasureSpec.AT_MOST
, but I might be missing something. I believe the logic should be instead:
if (widthMode == View.MeasureSpec.EXACTLY) {
mainSize = widthSize;
} else if (widthMode == View.MeasureSpec.AT_MOST) {
mainSize = Math.min(largestMainSize, widthSize);
} else {
mainSize = largestMainSize;
}
I've tested this change on a local branch and it behaves as expected. If that seems right to you I'm happy to open a PR with this change + tests.
In the current state, having mainSize
set to widthSize
will cause the flex shrink logic to be applied, which will force the children sizes to be something else than the width they want to/should be. Note that disabling flex shrink result in the expected behaviour and is a temporary workaround.
Link to code
Here is a link to as simple project which demonstrates the issue: https://github.com/OlivierGenez/flexbox-layout-unconstrained-width-bug.