Add color scheme import/export

data/themes/build.gradle.kts

@@ -1,6 +1,7 @@
 plugins {
     id("com.android.library")
     id("kotlin-android")
+    kotlin("plugin.serialization")
 }
 
 android {
@@ -36,6 +37,7 @@ android {
 
 dependencies {
     implementation(libs.bundles.kotlin)
+    implementation(libs.kotlinx.serialization.json)
     implementation(libs.androidx.core)
     implementation(libs.androidx.appcompat)
     implementation(libs.bundles.androidx.lifecycle)

data/themes/src/main/java/de/mm20/launcher2/themes/Serialization.kt

@@ -0,0 +1,57 @@
+package de.mm20.launcher2.themes
+
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.modules.SerializersModule
+import kotlinx.serialization.modules.contextual
+import kotlinx.serialization.modules.polymorphic
+
+internal class ColorRefSerializer: KSerializer<ColorRef> {
+    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("$", PrimitiveKind.STRING)
+
+    override fun deserialize(decoder: Decoder): ColorRef {
+        return Color(decoder.decodeString()) as ColorRef
+    }
+
+    override fun serialize(encoder: Encoder, value: ColorRef) {
+        encoder.encodeString(value.toString())
+    }
+}
+
+internal class StaticColorSerializer: KSerializer<StaticColor> {
+    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("#", PrimitiveKind.STRING)
+    override fun deserialize(decoder: Decoder): StaticColor {
+        return Color(decoder.decodeString()) as StaticColor
+    }
+
+    override fun serialize(encoder: Encoder, value: StaticColor) {
+        encoder.encodeString(value.toString())
+    }
+}
+
+internal val module = SerializersModule {
+    polymorphic(Color::class) {
+        subclass(ColorRef::class, ColorRefSerializer())
+        subclass(StaticColor::class, StaticColorSerializer())
+    }
+
+}
+
+val ThemeJson = Json {
+    serializersModule = module
+    useArrayPolymorphism = true
+}
+
+fun Theme.toJson(): String {
+    return ThemeJson.encodeToString(this)
+}
+
+fun Theme.Companion.fromJson(json: String): Theme {
+    return ThemeJson.decodeFromString(json)
+}

data/themes/src/main/java/de/mm20/launcher2/themes/Theme.kt

@@ -2,6 +2,8 @@ package de.mm20.launcher2.themes
 
 import de.mm20.launcher2.database.entities.ThemeEntity
 import hct.Hct
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
 import java.util.UUID
 
 enum class CorePaletteColor {
@@ -70,6 +72,7 @@ value class StaticColor(val color: Int) : Color {
     }
 }
 
+@Serializable
 data class CorePalette<out T : Int?>(
     val primary: T,
     val secondary: T,
@@ -84,6 +87,7 @@ val EmptyCorePalette = CorePalette<Int?>(null, null, null, null, null, null)
 typealias FullCorePalette = CorePalette<Int>
 typealias PartialCorePalette = CorePalette<Int?>
 
+@Serializable
 data class ColorScheme<out T : Color?>(
     val primary: T,
     val onPrimary: T,
@@ -127,8 +131,9 @@ data class ColorScheme<out T : Color?>(
 typealias FullColorScheme = ColorScheme<Color>
 typealias PartialColorScheme = ColorScheme<Color?>
 
+@Serializable
 data class Theme(
-    val id: UUID,
+    @Transient val id: UUID = UUID.randomUUID(),
     val builtIn: Boolean = false,
     val name: String,
     val corePalette: PartialCorePalette = EmptyCorePalette,