overlayColor property
Defines the ink response focus, hover, and splash colors.
This default null property can be used as an alternative to focusColor, hoverColor, highlightColor, and splashColor. If non-null, it is resolved against one of WidgetState.focused, WidgetState.hovered, and WidgetState.pressed. It's convenient to use when the parent widget can pass along its own WidgetStateProperty value for the overlay color.
WidgetState.pressed triggers a ripple (an ink splash), per the current Material Design spec. The overlayColor doesn't map a state to highlightColor because a separate highlight is not used by the current design guidelines. See https://material.io/design/interaction/states.html#pressed
If the overlay color is null or resolves to null, then focusColor, hoverColor, splashColor and their defaults are used instead.
See also:
- The Material Design specification for overlay colors and how they match a component's state: material.io/design/interaction/states.html#anatomy.
Implementation
final MaterialStateProperty<Color?>? overlayColor;