Module responsive 

Responsive value mapping: apply different values based on breakpoint.

Responsive<T> maps Breakpoint tiers to values of any type, with inheritance from smaller breakpoints. If no value is set for a given breakpoint, the value from the next smaller breakpoint is used.

Usage

use ftui_layout::{Responsive, Breakpoint};

let padding = Responsive::new(1)     // xs: 1
    .at(Breakpoint::Md, 2)           // md: 2
    .at(Breakpoint::Xl, 4);          // xl: 4

// sm inherits from xs → 1
// lg inherits from md → 2
assert_eq!(padding.resolve(Breakpoint::Sm), &1);
assert_eq!(padding.resolve(Breakpoint::Lg), &2);

Invariants

1. Xs always has a value (set via new()).
2. Inheritance follows breakpoint order: a missing tier inherits from the nearest smaller tier that has a value.
3. resolve() never fails — it always returns a reference.
4. Setting a value at a tier only affects that tier and tiers that inherit from it (does not affect tiers with explicit values).

Failure Modes

None — the type system guarantees a base value at Xs.

Structs

Responsive

A breakpoint-aware value with inheritance from smaller tiers.