Trait LayoutModifierNode 

pub trait LayoutModifierNode:
    Send
    + Sync
    + 'static {
    // Provided methods
    fn measure(
        &self,
        _scope: &mut MeasureScope<'_>,
    ) -> Result<LayoutResult, MeasurementError> { ... }
    fn measure_content(
        &self,
        _input: &LayoutModifierInput<'_>,
        _child: &mut dyn LayoutModifierChild,
    ) -> Result<LayoutResult, MeasurementError> { ... }
    fn measure_eq(&self, other: &Self) -> bool
       where Self: Sized + PartialEq { ... }
    fn placement_eq(&self, other: &Self) -> bool
       where Self: Sized + PartialEq { ... }
    fn place_children(
        &self,
        _scope: &PlacementScope<'_>,
        _inner: &PlacementResult,
    ) -> Option<PlacementResult> { ... }
}

A node-local layout modifier.

This is the single layout measurement contract shared by the innermost layout node (the measure policy applied at the innermost layer) and by wrapping layout modifiers. A node overrides either Self::measure (pure measure, applied at the innermost layer) or Self::measure_content (wrapping measure). An innermost node may override Self::place_children to update placements against cached child sizes. Wrapping modifiers can be measured again around that cached result to update their content bounds.

Provided Methods

fn measure( &self, _scope: &mut MeasureScope<'_>, ) -> Result<LayoutResult, MeasurementError>

Computes layout for this node when it is applied at the innermost layer.

fn measure_content( &self, _input: &LayoutModifierInput<'_>, _child: &mut dyn LayoutModifierChild, ) -> Result<LayoutResult, MeasurementError>

Measures and places the wrapped content.

fn measure_eq(&self, other: &Self) -> bool

where Self: Sized + PartialEq,

Compares measurement-relevant state for layout dirty tracking.

fn placement_eq(&self, other: &Self) -> bool

where Self: Sized + PartialEq,

Compares placement-relevant state for layout dirty tracking.

fn place_children( &self, _scope: &PlacementScope<'_>, _inner: &PlacementResult, ) -> Option<PlacementResult>

Recomputes child placements from cached child sizes.

An innermost layout node derives placements from the cached child sizes in scope. Returning None means it cannot place without re-measuring. Wrapping modifiers use Self::measure_content around the cached result so drawing receives the same content bounds as child placement.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl LayoutModifierNode for DefaultLayoutNode