compose color to html color

UtilsKtTest.kt

import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.toArgb
import io.ktor.util.*
import kotlin.math.roundToInt
import kotlin.test.DefaultAsserter.assertEquals
import kotlin.test.Test

class UtilsKtTest {

    private val dataSet = listOf(
        Color.Blue to HtmlColor(rgb = HtmlRGB(red = 0u, green = 0u, blue = 255u), rgbHex = "0000FF", alpha = 1f),
        Color.Red to HtmlColor(rgb = HtmlRGB(red = 255u, green = 0u, blue = 0u), rgbHex = "FF0000", alpha = 1f),
        Color.Green to HtmlColor(rgb = HtmlRGB(red = 0u, green = 255u, blue = 0u), rgbHex = "00FF00", alpha = 1f),
        Color(0xFF69359C) to HtmlColor(rgb = HtmlRGB(red = 105u, green = 53u, blue = 156u), rgbHex = "69359C", alpha = 1f),
        Color(0xe7d743c3) to HtmlColor(rgb = HtmlRGB(red = 215u, green = 67u, blue = 195u), rgbHex = "D743C3", alpha = 0.91f),
        Color(0xe7d743c3) to HtmlColor(rgb = HtmlRGB(red = 215u, green = 67u, blue = 195u), rgbHex = "D743C3", alpha = 0.91f),
        Color(0xf301e76e) to HtmlColor(rgb = HtmlRGB(red = 1u, green = 231u, blue = 110u), rgbHex = "01E76E", alpha = 0.95f),
        Color(0x93e8ffdd) to HtmlColor(rgb = HtmlRGB(red = 232u, green = 255u, blue = 221u), rgbHex = "E8FFDD", alpha = 0.58f),
        Color(0x38d08517) to HtmlColor(rgb = HtmlRGB(red = 208u, green = 133u, blue = 23u), rgbHex = "D08517", alpha = 0.22f),
    )

    @Test
    fun testGetColorSet() {
        dataSet.forEach {
            val color = it.first.toHtmlColor()
            assertEquals(
                message = color.toString(),
                expected = it.second,
                actual = color
            )
        }
    }
}



fun Color.toHtmlColor(): HtmlColor {
    val argb = toArgb().toUInt()

    val a = (argb shr 24) and 0xFFu
    val r = (argb shr 16) and 0xFFu
    val g = (argb shr 8) and 0xFFu
    val b = argb and 0xFFu

    val rgb = HtmlRGB(
        red = r.toUByte(),
        green = g.toUByte(),
        blue = b.toUByte(),
    )

    return HtmlColor(
        rgbHex = rgb.toHex(),
        rgb = rgb,
        alpha = ((a.toFloat() / 255.0f) * 100).roundToInt() / 100f
    )
}


data class HtmlColor(
    val rgbHex: String,
    val rgb: HtmlRGB,
    val alpha: Float = 0f
)

data class HtmlRGB(
    val red: UByte,
    val green: UByte,
    val blue: UByte,
)

fun HtmlRGB.toHex(): String {
    return hex(byteArrayOf(this.red.toByte(), this.green.toByte(), this.blue.toByte()))
}

private val digits = "0123456789ABCDEF".toCharArray()

/**
 * Encode bytes to HEX string.
 *
 * Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
 */
fun hex(bytes: ByteArray): String {
    val result = CharArray(bytes.size * 2)
    var resultIndex = 0
    val digits = digits

    for (index in 0 until bytes.size) {
        val b = bytes[index].toInt() and 0xff
        result[resultIndex++] = digits[b shr 4]
        result[resultIndex++] = digits[b and 0x0f]
    }

    return result.concatToString()
}