Add color picker component

ui/src/main/java/de/mm20/launcher2/ui/component/ColorPicker.kt

@@ -0,0 +1,125 @@
+package de.mm20.launcher2.ui.component
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.*
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.OutlinedTextField
+import androidx.compose.material.Slider
+import androidx.compose.material.Text
+import androidx.compose.runtime.*
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.toArgb
+import androidx.compose.ui.unit.dp
+import androidx.core.graphics.ColorUtils
+import de.mm20.launcher2.ui.ktx.toHexString
+
+@Composable
+fun ColorPicker(
+    value: Color,
+    onValueChanged: (Color) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    val hsl = remember { floatArrayOf(0f, 0f, 0f) }
+
+    ColorUtils.colorToHSL(value.toArgb(), hsl)
+
+    val hue = hsl[0]
+    val sat = hsl[1]
+    val lig = hsl[2]
+
+    var hex by remember { mutableStateOf(value.toHexString()) }
+
+    LaunchedEffect(value) {
+        hex = value.toHexString()
+    }
+
+    Column(modifier = modifier) {
+        Box(
+            modifier = Modifier
+                .fillMaxWidth()
+                .height(128.dp)
+                .background(value)
+        )
+        SliderRow("H") {
+            Slider(
+                value = hue,
+                valueRange = 0f..360f,
+                onValueChange = {
+                    val newValue = Color(ColorUtils.HSLToColor(floatArrayOf(it, sat, lig)))
+                    onValueChanged(newValue)
+                }
+            )
+        }
+        SliderRow("S") {
+            Slider(
+                value = sat,
+                valueRange = 0f..1f,
+                onValueChange = {
+                    val newValue = Color(ColorUtils.HSLToColor(floatArrayOf(hue, it, lig)))
+                    onValueChanged(newValue)
+                }
+            )
+        }
+        SliderRow("L") {
+            Slider(
+                value = lig,
+                valueRange = 0f..1f,
+                onValueChange = {
+                    val newValue = Color(ColorUtils.HSLToColor(floatArrayOf(hue, sat, it)))
+                    onValueChanged(newValue)
+                }
+            )
+        }
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(top = 8.dp, start = 16.dp, end = 16.dp),
+            verticalAlignment = Alignment.CenterVertically
+        ) {
+
+            Text(
+                "Hex: ",
+                modifier = Modifier.weight(2f),
+                style = MaterialTheme.typography.subtitle2
+            )
+            OutlinedTextField(
+                value = hex,
+                onValueChange = {
+                    if (it.matches(Regex("^#([a-fA-F0-9]{6})$"))) {
+                        val colorInt = it.substring(1).toInt(16)
+                        onValueChanged(Color(colorInt).copy(alpha = 1f))
+                    } else {
+                        hex = it
+                    }
+                },
+                modifier = Modifier.weight(6f)
+            )
+        }
+    }
+}
+
+@Composable
+private fun SliderRow(
+    label: String,
+    content: @Composable () -> Unit
+) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(vertical = 4.dp, horizontal = 16.dp),
+        verticalAlignment = Alignment.CenterVertically
+    ) {
+        Text(
+            label,
+            modifier = Modifier.weight(1f),
+            style = MaterialTheme.typography.subtitle2
+        )
+        Box(
+            modifier = Modifier.weight(7f)
+        ) {
+            content()
+        }
+    }
+}

ui/src/main/java/de/mm20/launcher2/ui/ktx/Color.kt

@@ -0,0 +1,14 @@
+package de.mm20.launcher2.ui.ktx
+
+import androidx.compose.ui.graphics.Color
+import kotlin.math.roundToInt
+
+fun Color.toHexString(): String {
+    val red = (this.red * 255).roundToInt()
+    val green = (this.green * 255).roundToInt()
+    val blue = (this.blue * 255).roundToInt()
+    return "#" +
+            red.toString(16).run { if (length == 1) "0$this" else this } +
+            green.toString(16).run { if (length == 1) "0$this" else this } +
+            blue.toString(16).run { if (length == 1) "0$this" else this }
+}