Trait MeasurePolicy 

pub trait MeasurePolicy {
    // Required methods
    fn measure(
        &self,
        scope: &dyn MeasureScope,
        measurables: &[Box<dyn Measurable>],
        constraints: Constraints,
    ) -> MeasureResult;
    fn min_intrinsic_width(
        &self,
        measurables: &[Box<dyn Measurable>],
        height: f32,
    ) -> f32;
    fn max_intrinsic_width(
        &self,
        measurables: &[Box<dyn Measurable>],
        height: f32,
    ) -> f32;
    fn min_intrinsic_height(
        &self,
        measurables: &[Box<dyn Measurable>],
        width: f32,
    ) -> f32;
    fn max_intrinsic_height(
        &self,
        measurables: &[Box<dyn Measurable>],
        width: f32,
    ) -> f32;

    // Provided methods
    fn measure_into(
        &self,
        scope: &dyn MeasureScope,
        measurables: &[Box<dyn Measurable>],
        constraints: Constraints,
        placements: &mut Vec<Placement>,
    ) -> Measurement { ... }
    fn measure_hold(
        &self,
        _measurables: &[Box<dyn Measurable>],
        _constraints: Constraints,
        _size: Size,
    ) -> Option<ConstraintsHold> { ... }
}

Policy responsible for measuring and placing children.

Required Methods

fn measure( &self, scope: &dyn MeasureScope, measurables: &[Box<dyn Measurable>], constraints: Constraints, ) -> MeasureResult

Runs the measurement pass with the provided children and constraints.

fn min_intrinsic_width( &self, measurables: &[Box<dyn Measurable>], height: f32, ) -> f32

Computes the minimum intrinsic width of this policy.

fn max_intrinsic_width( &self, measurables: &[Box<dyn Measurable>], height: f32, ) -> f32

Computes the maximum intrinsic width of this policy.

fn min_intrinsic_height( &self, measurables: &[Box<dyn Measurable>], width: f32, ) -> f32

Computes the minimum intrinsic height of this policy.

fn max_intrinsic_height( &self, measurables: &[Box<dyn Measurable>], width: f32, ) -> f32

Computes the maximum intrinsic height of this policy.

Provided Methods

fn measure_into( &self, scope: &dyn MeasureScope, measurables: &[Box<dyn Measurable>], constraints: Constraints, placements: &mut Vec<Placement>, ) -> Measurement

Runs measurement into caller-owned placement storage.

The default preserves the public MeasurePolicy::measure contract for custom policies. Built-in policies override this to avoid allocating a fresh placement vector on every measure pass.

fn measure_hold( &self, _measurables: &[Box<dyn Measurable>], _constraints: Constraints, _size: Size, ) -> Option<ConstraintsHold>

The incoming constraints the measure that sized the layout size under constraints holds for, when the policy can tell: see crate::ConstraintsHold. None, the default, holds for constraints alone.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors