Add Basic CSS Color Parsing

codecov.yml

@@ -2,5 +2,6 @@ coverage:
   status:
     patch: off
 fixes:
-  - "com/juul/krayon/canvas::"
   - "com/juul/krayon/chart::"
+  - "com/juul/krayon/color::"
+  - "com/juul/krayon/kanvas::"

color/api/color.api

@@ -18,6 +18,7 @@ public final class com/juul/krayon/color/Color {
 	public static final fun getRgb-impl (I)I
 	public fun hashCode ()I
 	public static fun hashCode-impl (I)I
+	public static final fun toHexString-impl (I)Ljava/lang/String;
 	public fun toString ()Ljava/lang/String;
 	public static fun toString-impl (I)Ljava/lang/String;
 	public final synthetic fun unbox-impl ()I
@@ -32,6 +33,11 @@ public final class com/juul/krayon/color/RandomKt {
 	public static synthetic fun nextColor$default (Lkotlin/random/Random;ZILjava/lang/Object;)I
 }
 
+public final class com/juul/krayon/color/ToColorKt {
+	public static final fun toColor (Ljava/lang/String;)I
+	public static final fun toColorOrNull (Ljava/lang/String;)Lcom/juul/krayon/color/Color;
+}
+
 public final class com/juul/krayon/color/WebColorsKt {
 	public static final fun getAliceBlue ()I
 	public static final fun getAntiqueWhite ()I

color/src/commonMain/kotlin/Color.kt

@@ -50,7 +50,18 @@ public inline class Color(public val argb: Int) {
         blue: Int = this.blue,
     ): Color = Color(alpha, red, green, blue)
 
-    override fun toString(): String = "Color(#${argb.toString(HEX_BASE).padStart(HEX_LENGTH, '0')})"
+    /** Returns this as a string in web-friendly hex notation. */
+    public fun toHexString(): String = buildString {
+        append('#')
+        append(red.toString(HEX_BASE).padStart(2, '0'))
+        append(green.toString(HEX_BASE).padStart(2, '0'))
+        append(blue.toString(HEX_BASE).padStart(2, '0'))
+        if (alpha != 0xFF) {
+            append(alpha.toString(HEX_BASE).padStart(2, '0'))
+        }
+    }
+
+    override fun toString(): String = "Color(${toHexString()})"
 }
 
 private fun Float.toColorComponent(): Int {

color/src/commonMain/kotlin/Constants.kt

@@ -9,7 +9,6 @@ internal const val SHIFT_GREEN = 8
 internal const val SHIFT_BLUE = 0
 
 internal const val HEX_BASE = 16
-internal const val HEX_LENGTH = 8
 
 internal const val COMPONENT_MIN = 0x00
 internal const val COMPONENT_MAX = 0xFF

color/src/commonMain/kotlin/ToColor.kt

@@ -0,0 +1,47 @@
+package com.juul.krayon.color
+
+private const val HEX = "[a-f0-9]"
+
+private val RGB = """($HEX)($HEX)($HEX)""".toRegex(RegexOption.IGNORE_CASE)
+private val RGBA = """($HEX)($HEX)($HEX)($HEX)""".toRegex(RegexOption.IGNORE_CASE)
+private val RRGGBB = """($HEX{2})($HEX{2})($HEX{2})""".toRegex(RegexOption.IGNORE_CASE)
+private val RRGGBBAA = """($HEX{2})($HEX{2})($HEX{2})($HEX{2})""".toRegex(RegexOption.IGNORE_CASE)
+
+public fun String.toColor(): Color =
+    when {
+        this.startsWith("#") -> parseHexNotation(this)
+        else -> keywordMap[this.toLowerCase()]
+    } ?: throw IllegalArgumentException("Unknown color: `$this`.")
+
+public fun String.toColorOrNull(): Color? =
+    try {
+        toColor()
+    } catch (e: IllegalArgumentException) {
+        null
+    }
+
+private fun parseHexNotation(text: String): Color {
+    require(text.startsWith("#")) { "Hex notation must start with a pound sign (#)." }
+    val hexText = text.substring(1)
+    val match = when (hexText.length) {
+        3 -> RGB.matchEntire(hexText)
+        4 -> RGBA.matchEntire(hexText)
+        6 -> RRGGBB.matchEntire(hexText)
+        8 -> RRGGBBAA.matchEntire(hexText)
+        else -> throw IllegalArgumentException("Incorrect length. Hex notation must contain exactly 3, 4, 6, or 8 hexadecimal characters.")
+    } ?: throw IllegalArgumentException("Text is not a hexadecimal string. Each character must match the regex [a-fA-F0-9].")
+    val red = match.groupValues[1]
+    val green = match.groupValues[2]
+    val blue = match.groupValues[3]
+    val alpha = match.groupValues.getOrNull(4) ?: "ff"
+    return Color(parseHexComponent(alpha), parseHexComponent(red), parseHexComponent(green), parseHexComponent(blue))
+}
+
+private fun parseHexComponent(component: String): Int =
+    if (component.length == 1) {
+        // Per MDN, "The three-digit notation (#RGB) is a shorter version of the six-digit form (#RRGGBB)."
+        // Achieve that by just calling this function again with the component repeated.
+        parseHexComponent(component + component)
+    } else {
+        component.toInt(HEX_BASE)
+    }

color/src/commonMain/kotlin/WebColors.kt

@@ -186,3 +186,160 @@ public val gainsboro: Color = Color(0xFFDCDCDC.toInt())
 
 public val transparent: Color = Color(0x00000000.toInt())
 public val rebeccaPurple: Color = Color(0xFF663399.toInt())
+
+internal val keywordMap = mapOf(
+    "white" to white,
+    "silver" to silver,
+    "gray" to gray,
+    "black" to black,
+
+    "red" to red,
+    "maroon" to maroon,
+    "yellow" to yellow,
+    "olive" to olive,
+    "lime" to lime,
+    "green" to green,
+    "aqua" to aqua,
+    "teal" to teal,
+    "blue" to blue,
+    "navy" to navy,
+    "fuchsia" to fuchsia,
+    "purple" to purple,
+
+    "mediumvioletred" to mediumVioletRed,
+    "deeppink" to deepPink,
+    "palevioletred" to paleVioletRed,
+    "hotpink" to hotPink,
+    "lightpink" to lightPink,
+    "pink" to pink,
+
+    "darkred" to darkRed,
+    "firebrick" to firebrick,
+    "crimson" to crimson,
+    "indianred" to indianRed,
+    "lightcoral" to lightCoral,
+    "salmon" to salmon,
+    "lightsalmon" to lightSalmon,
+
+    "orangered" to orangeRed,
+    "tomato" to tomato,
+    "darkorange" to darkOrange,
+    "coral" to coral,
+    "orange" to orange,
+
+    "darkkhaki" to darkKhaki,
+    "gold" to gold,
+    "khaki" to khaki,
+    "peachpuff" to peachPuff,
+    "palegoldenrod" to paleGoldenrod,
+    "moccasin" to moccasin,
+    "papayawhip" to papayaWhip,
+    "lightgoldenrodyellow" to lightGoldenrodYellow,
+    "lemonchiffon" to lemonChiffon,
+    "lightyellow" to lightYellow,
+
+    "brown" to brown,
+    "saddlebrown" to saddleBrown,
+    "sienna" to sienna,
+    "chocolate" to chocolate,
+    "darkgoldenrod" to darkGoldenrod,
+    "peru" to peru,
+    "rosybrown" to rosyBrown,
+    "goldenrod" to goldenrod,
+    "sandybrown" to sandyBrown,
+    "tan" to tan,
+    "burlywood" to burlywood,
+    "wheat" to wheat,
+    "navajowhite" to navajoWhite,
+    "bisque" to bisque,
+    "blanchedalmond" to blanchedAlmond,
+    "cornsilk" to cornsilk,
+
+    "darkgreen" to darkGreen,
+    "darkolivegreen" to darkOliveGreen,
+    "forestgreen" to forestGreen,
+    "seagreen" to seaGreen,
+    "olivedrab" to oliveDrab,
+    "mediumseagreen" to mediumSeaGreen,
+    "limegreen" to limeGreen,
+    "springgreen" to springGreen,
+    "mediumspringgreen" to mediumSpringGreen,
+    "darkseagreen" to darkSeaGreen,
+    "mediumaquamarine" to mediumAquamarine,
+    "yellowgreen" to yellowGreen,
+    "lawngreen" to lawnGreen,
+    "chartreuse" to chartreuse,
+    "lightgreen" to lightGreen,
+    "greenyellow" to greenYellow,
+    "palegreen" to paleGreen,
+
+    "darkcyan" to darkCyan,
+    "lightseagreen" to lightSeaGreen,
+    "cadetblue" to cadetBlue,
+    "darkturquoise" to darkTurquoise,
+    "mediumturquoise" to mediumTurquoise,
+    "turquoise" to turquoise,
+    "cyan" to cyan,
+    "aquamarine" to aquamarine,
+    "paleturquoise" to paleTurquoise,
+    "lightcyan" to lightCyan,
+
+    "darkblue" to darkBlue,
+    "mediumblue" to mediumBlue,
+    "midnightblue" to midnightBlue,
+    "royalblue" to royalBlue,
+    "steelblue" to steelBlue,
+    "dodgerblue" to dodgerBlue,
+    "deepskyblue" to deepSkyBlue,
+    "cornflowerblue" to cornflowerBlue,
+    "skyblue" to skyBlue,
+    "lightskyblue" to lightSkyBlue,
+    "lightsteelblue" to lightSteelBlue,
+    "lightblue" to lightBlue,
+    "powderblue" to powderBlue,
+
+    "indigo" to indigo,
+    "darkmagenta" to darkMagenta,
+    "darkviolet" to darkViolet,
+    "darkslateblue" to darkSlateBlue,
+    "blueviolet" to blueViolet,
+    "darkorchid" to darkOrchid,
+    "magenta" to magenta,
+    "slateblue" to slateBlue,
+    "mediumslateblue" to mediumSlateBlue,
+    "mediumorchid" to mediumOrchid,
+    "mediumpurple" to mediumPurple,
+    "orchid" to orchid,
+    "violet" to violet,
+    "plum" to plum,
+    "thistle" to thistle,
+    "lavender" to lavender,
+
+    "mistyrose" to mistyRose,
+    "antiquewhite" to antiqueWhite,
+    "linen" to linen,
+    "beige" to beige,
+    "whitesmoke" to whiteSmoke,
+    "lavenderblush" to lavenderBlush,
+    "oldlace" to oldLace,
+    "aliceblue" to aliceBlue,
+    "seashell" to seashell,
+    "ghostwhite" to ghostWhite,
+    "honeydew" to honeydew,
+    "floralwhite" to floralWhite,
+    "azure" to azure,
+    "mintcream" to mintCream,
+    "snow" to snow,
+    "ivory" to ivory,
+
+    "darkslategray" to darkSlateGray,
+    "dimgray" to dimGray,
+    "slategray" to slateGray,
+    "lightslategray" to lightSlateGray,
+    "darkgray" to darkGray,
+    "lightgray" to lightGray,
+    "gainsboro" to gainsboro,
+
+    "transparent" to transparent,
+    "rebeccapurple" to rebeccaPurple
+)

color/src/commonTest/kotlin/ColorTests.kt

@@ -2,6 +2,7 @@ package com.juul.krayon.color
 
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
 
 class ColorTests {
 
@@ -29,4 +30,29 @@ class ColorTests {
     fun checkComponentsAreMasked() {
         assertEquals((0x23456789).toInt(), Color(alpha = 0x123, red = 0x345, green = 0x567, blue = 0x789).argb)
     }
+
+    @Test
+    fun colorConstructor_withFloatInput_matchesIntegerInput() {
+        assertEquals(red, Color(red = 1f, green = 0f, blue = 0f))
+    }
+
+    @Test
+    fun colorConstructor_withNegativeFloatInput_throwsException() {
+        assertFailsWith<IllegalArgumentException> { Color(red = -1f, green = 0f, blue = 0f) }
+    }
+
+    @Test
+    fun colorConstructor_withLargeFloatInput_throwsException() {
+        assertFailsWith<IllegalArgumentException> { Color(red = 2f, green = 0f, blue = 0f) }
+    }
+
+    @Test
+    fun toHexString_withNoTransparency_omitsAlpha() {
+        assertEquals("#ff0000", red.toHexString())
+    }
+
+    @Test
+    fun toHexString_withTransparency_includesAlpha() {
+        assertEquals("#ff000080", red.copy(alpha = 0x80).toHexString())
+    }
 }

color/src/commonTest/kotlin/OperationsTests.kt

@@ -0,0 +1,12 @@
+package com.juul.krayon.color
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class OperationsTests {
+
+    @Test
+    fun lerp_fromWhiteToBlack_isGray() {
+        assertEquals(gray, lerp(white, black, 0.5f))
+    }
+}

color/src/commonTest/kotlin/RandomTests.kt

@@ -0,0 +1,31 @@
+package com.juul.krayon.color
+
+import kotlin.random.Random
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class RandomTests {
+
+    private val saturatedRandom = object : Random() {
+        override fun nextBits(bitCount: Int): Int = 0xFFFFFFFF.toInt() ushr (32 - bitCount)
+    }
+
+    private val zeroRandom = object : Random() {
+        override fun nextBits(bitCount: Int): Int = 0
+    }
+
+    @Test
+    fun nextColor_withSaturatedRandom_isWhite() {
+        assertEquals(white.rgb, saturatedRandom.nextColor().rgb)
+    }
+
+    @Test
+    fun nextColor_withDefaultArg_isOpaque() {
+        assertEquals(0xFF, zeroRandom.nextColor().alpha)
+    }
+
+    @Test
+    fun nextColor_withOpaqueFalse_canProduceTransparency() {
+        assertEquals(0, zeroRandom.nextColor(isOpaque = false).alpha)
+    }
+}