Pre-Android 12 detection on whether a color is dark or light from https://stackoverflow.com/questions/3942878/how-to-decide-font-color-in-white-or-black-depending-on-background-color

WidgetUtil.kt

fun colorIsDarkAdvanced(bgColor: Int): Boolean {
    // hexToB
    val uicolors = doubleArrayOf(
        bgColor.red.toDouble() / 255.0,
        bgColor.green.toDouble() / 255.0,
        bgColor.blue.toDouble() / 255.0
    )
    val c = uicolors.map { col ->
        if (col <= 0.03928) {
            col / 12.92
        } else {
            Math.pow((col + 0.055) / 1.055, 2.4)
        }
    }
    val L = 0.2126 * c[0] + 0.7152 * c[1] + 0.0722 * c[2]
    return L <= 0.179
}