Type Alias MeasureFn 

pub type MeasureFn = Box<dyn FnMut(f32) -> (f32, f32)>;

Per-node measure callback: given the available main-axis width, returns the node’s intrinsic (width, height). Used for text nodes whose height depends on how many lines the content wraps into at the resolved width.

Aliased Type

pub struct MeasureFn(/* private fields */);