ContrastPolicy class final

Label-solving policy: floors plus the two WCAG-2 blind-spot heuristics (research §4.5). Immutable; configurable per family or Accessible lock.

Constructors

ContrastPolicy({double minRatio = ratioText, double darkFaceRatio = ratioAccessible, double darkFaceY = yDarkFace, bool polarityRule = true, bool darkFaceBoost = true})

const

Properties

darkFaceBoost → bool

Solve labels on dark faces to darkFaceRatio.

final

darkFaceRatio → double

Target on faces with luminance below darkFaceY (when darkFaceBoost).

final

darkFaceY → double

Luminance under which a face counts as dark.

final

hashCode → int

The hash code for this object.

no setter, inherited

minRatio → double

The hard floor every label must reach.

final

polarityRule → bool

Prefer a light label on mid-tone faces (0.179 < Y < 0.342) whenever it reaches the floor.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

inPolarityBand(double faceY) → bool

Whether a face of luminance faceY is in the mid-tone polarity band.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

targetFor(double faceY) → double

The ratio to aim for on a face of luminance faceY.

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Constants

accessible → const ContrastPolicy

Accessible lock: 7:1 floor everywhere.

standard → const ContrastPolicy

Standard policy: 4.5:1 floor, 7:1 on dark faces, polarity rule on.