[android-core] Calculate contrast colour against dynamic app background correctly

[wax911]

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Description of Bug

Contrast adjustments required for a few widgets that dynamically use the accent colour from a media image. The problem comes in when we have a colour that does not have enough contrast with a dark background, e.g. when you switch to night mode.

Reproduction Steps

• Open this link with the app https://anilist.co/anime/127230/Chainsaw-Man
• Switch to dark mode on your device

Screenshots/Videos

List (dark)	Detail (dark)	Detail (light)

Additional Context

See co.anitrend.core.android.helpers.color.ColorExtensions which is what we use to infer and shift colours that would typically not contrast enough with the background colour of the app at any given point in time.

anitrend-v2/android-core/src/main/kotlin/co/anitrend/core/android/helpers/color/ColorExtensions.kt

Lines 29 to 43 in ff08b5d

	/** Checks if a color has enough contrast */
	fun Int.hasEnoughContrastFor(
	@ColorInt backgroundColor: Int
	) = ColorUtils.calculateContrast(
	this,
	backgroundColor
	) > 1.8f
	/** Decreases the lightness of the color by the [factor] */
	fun Int.increaseContrastBy(factor: Float): Int {
	val hsl = FloatArray(3)
	ColorUtils.colorToHSL(this, hsl)
	hsl[2] = hsl[2] * factor
	return ColorUtils.HSLToColor(hsl)
	}

[wax911]

A follow up to this would most likely introduce something like the following code sample, given this is a very rough draft

fun Int.adjustColorForContrast(@ColorInt backgroundColor: Int): Int {
   val color = // convert `this` to `Color`
    val background = // convert `backgroundColor` to `Color`
    val colorLuminance = 0.2126 * color.red + 0.7152 * color.green + 0.0722 * color.blue
    val backgroundLuminance = 0.2126 * background.red + 0.7152 * background.green + 0.0722 * background.blue
    val contrastRatio = (colorLuminance + 0.05) / (backgroundLuminance + 0.05)
    val threshold = 4.5
    if (contrastRatio < threshold) {
        return color.inv() // Invert the color
    }
    return color
}