Struct ReserveLayout 

pub struct ReserveLayout;

Reserve at least the size of a sample child, then lay the content out inside it.

The problem it solves: a numeric readout beside a slider changes width as the value changes (1 is narrower than 8 in a proportional font, and 9 → 10 adds a whole glyph), so the row reflows on every drag and the control you are aiming at moves. A hardcoded width “fixes” that until the reader raises their accessibility text size, at which point the number is clipped.

Reserving a sample measures a real piece in the real font at the real size, so the reservation scales with the text exactly as the content does. children[0] is the sample (built transparent by Decorate::reserving, so it never paints and is placed at zero size); children[1] is the content, which receives the full reserved bounds and aligns itself.

Trait Implementations

impl Layout for ReserveLayout

fn measure( &self, cx: &mut dyn LayoutOps, children: &[RNode], p: Proposal, ) -> Size

fn place(&self, cx: &mut dyn LayoutOps, children: &[RNode], bounds: Rect)

fn baseline( &self, _cx: &mut dyn LayoutOps, _children: &[RNode], _size: Size, ) -> Option<f64>

Where this node’s own first text baseline falls, measured from the top of a box of size (docs/baseline.md). None (the default) means the node has no baseline to offer, so a baseline-aligned parent falls back to box alignment for it.