kCupertinoFocusColorBrightness top-level constant
The relative values needed to transform a color to it's equivalent focus outline color.
These are used to draw a focus ring around CupertinoSwitch, CupertinoCheckbox, CupertinoRadio and CupertinoButton.
See also:
Implementation
const double kCupertinoFocusColorOpacity = 0.80,
kCupertinoFocusColorBrightness = 0.69,
kCupertinoFocusColorSaturation = 0.835;