Support multiple groups, remove Compose's MutableState from AppState

app/src/main/java/com/kernelmaft/zanbur/app-state.kt

@@ -1,19 +1,24 @@
 package com.kernelmaft.zanbur
 
-import androidx.compose.runtime.MutableState
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.setValue
-
 
 object AppState {
-	val groups : MutableState < List <Group> > = mutableStateOf ( emptyList () )
+	val groups : List <Group> get () = groupsAsMutable
+	private var groupsAsMutable : List <Group> = emptyList ()
 
-	fun setCurrentScene ( groupId : Int , currentScene : Scene ) {
+	private val subscribers : MutableList < ( List <Group> ) -> Unit > = mutableListOf ()
-		var groups by this . groups
+
-		groups = groups . map {
+	fun subscribe ( subscriber : ( List <Group> ) -> Unit ) = subscribers . add (subscriber)
-			if ( it . id == groupId ) it . copy ( currentScene = currentScene )
+
-			else it
+	fun addGroup ( group : Group ) {
+		groupsAsMutable += group
+		subscribers . forEach { it (groups) }
 	}
+
+	fun setCurrentScene ( groupId : Int , scene : Scene ) {
+		groupsAsMutable = groupsAsMutable . mapIndexed { index , group ->
+			if ( index == groupId ) group . copy ( currentScene = scene )
+			else group
+		}
+		subscribers . forEach { it (groups) }
 	}
 }

app/src/main/java/com/kernelmaft/zanbur/components.kt

@@ -1,6 +1,8 @@
 package com.kernelmaft.zanbur
 
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
 import androidx.compose.material3.Button
 import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.Text
@@ -8,15 +10,14 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 
 
-@Composable fun SceneSwitcher (
+@Composable fun SceneSwitcher ( group : Group , onSwitch : (Scene) -> Unit ) {
-	scenes : Collection <Scene> ,
+	CenteringColumn {
-	currentScene : Scene ? ,
+		Text ( group . name )
-	onSwitch : (Scene) -> Unit ,
+		Spacer ( Modifier . height ( compactSpacing ) )
-) {
+
-	CenteredColumn {
+		for ( scene in group . scenes ) {
-		for ( scene in scenes ) {
 			val colors =
-				if ( scene . id == currentScene ?. id ) ButtonDefaults . buttonColors ()
+				if ( scene . id == group . currentScene ?. id ) ButtonDefaults . buttonColors ()
 				else ButtonDefaults . filledTonalButtonColors ()
 
 			Button ( { onSwitch (scene) } , Modifier . fillMaxWidth () , true , ButtonDefaults . shape , colors ) {

app/src/main/java/com/kernelmaft/zanbur/main.kt

@@ -7,14 +7,13 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.width
 import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Text
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
@@ -27,15 +26,17 @@ class MainActivity : ComponentActivity () {
 	override fun onCreate ( savedInstanceState : Bundle ? ) {
 		super . onCreate (savedInstanceState)
 
-		var groups by AppState . groups
+		Config . groups . forEach { AppState . addGroup (it) }
-		groups = Config . groups
+
+		var groups by mutableStateOf ( AppState . groups )
+		AppState . subscribe { groups = it }
 
 		lifecycleScope . launch (IO) {
 			val prefs = applicationContext . dataStore . data . firstOrNull ()
 			if ( prefs != null ) {
 				val savedSceneName = prefs [ stringPreferencesKey ("scene") ]
 				if ( savedSceneName != null ) {
-					val savedScene = groups [0] . scenes . find { it . name == savedSceneName }
+					val savedScene = AppState . groups [0] . scenes . find { it . name == savedSceneName }
 					if ( savedScene != null ) {
 						AppState . setCurrentScene ( 0 , savedScene )
 					}
@@ -47,14 +48,14 @@ class MainActivity : ComponentActivity () {
 		setContent {
 			ZanburTheme {
 				Scaffold { scaffoldPadding ->
-					CenteredColumn ( Modifier . padding (scaffoldPadding) . fillMaxSize () ) {
+					CenteringColumn ( Modifier . padding (scaffoldPadding) . fillMaxSize () ) {
 
-						CenteredColumn ( Modifier . width ( 300 . dp ) ) {
+						Column ( Modifier . width ( 300 . dp ) ) {
-							Text (groups [0] . name)
+							groups . forEach { group ->
-							Spacer ( Modifier . height ( compactSpacing ) )
+								SceneSwitcher (group) {
-							SceneSwitcher ( groups [0] . scenes , groups [0] . currentScene ) {
+									AppState . setCurrentScene ( group . id , it )
-								AppState . setCurrentScene ( 0 , it )
+									publishSceneChange ( group , it )
-								publishSceneChange ( groups [0] , it )
+								}
 							}
 						}
 					}
@@ -68,9 +69,7 @@ class MainActivity : ComponentActivity () {
 	override fun onStop () {
 		super . onStop ()
 
-		val groups by AppState . groups
+		val currentScene = AppState . groups [0] . currentScene
-		val currentScene = groups [0] . currentScene
-
 		if ( currentScene != null ) lifecycleScope . launch (IO) {
 			applicationContext . dataStore . edit {
 				it [ stringPreferencesKey ("scene") ] = currentScene . name

app/src/main/java/com/kernelmaft/zanbur/ontology.kt

@@ -4,7 +4,7 @@ package com.kernelmaft.zanbur
 data class Group (
 	val id : Int ,
 	val name : String ,
-	val scenes : Collection <Scene> ,
+	val scenes : List <Scene> ,
 	val currentScene : Scene ? = null ,
 )
 

app/src/main/java/com/kernelmaft/zanbur/theme.kt

@@ -30,8 +30,7 @@ val compactSpacing = 16 . dp
 	MaterialTheme ( colorScheme, shapes , typography , content )
 }
 
-@Composable fun CenteredColumn (
+@Composable fun CenteringColumn (
 	modifier : Modifier = Modifier ,
 	content : @Composable ColumnScope . () -> Unit ,
-) =
+) = Column ( modifier , Center , CenterHorizontally , content )
-	Column ( modifier , Center , CenterHorizontally , content )