Use case

I want to use the squircle corners of iOS for my input fields. There is the RoundedSuperellipseBorder to do exactly that, but a TextField works only with InputBorders that extend from ShapeBorder, which makes those classes sibling classes of OutlinedBorder which RoundedSuperellipseBorder extends from.

Proposal

I believe there should be a RoundedSuperellipseInputBorder that fills the gap. On iOS native text fields use the same corner math, see the search bar in the contacts app, so this is necessary when aiming for platform respective UI.