skip the startup reveal animation and seed the first colour

The mini player and tab bar no longer expand or animate their inset when playback is
restored at launch, and the first artwork colour lands without a 600ms fade from the
base scheme. The last active artwork seed is persisted and read back synchronously so
the mini player can paint with it on its first frame.

app/src/main/kotlin/com/subtracks/SubtracksApp.kt

@@ -5,6 +5,7 @@ import coil3.ImageLoader
 import coil3.SingletonImageLoader
 import coil3.annotation.DelicateCoilApi
 import coil3.network.okhttp.OkHttpNetworkFetcherFactory
+import com.subtracks.data.prefs.UserPreferences
 import com.subtracks.data.repo.ArtworkSeedStore
 import com.subtracks.di.appModule
 import com.subtracks.ui.theme.ArtworkSeedCache
@@ -24,7 +25,7 @@ class SubtracksApp : Application() {
             startKoin {
                 modules(appModule(this@SubtracksApp, http))
             }.koin
-        ArtworkSeedCache.install(koin.get<ArtworkSeedStore>())
+        ArtworkSeedCache.install(koin.get<ArtworkSeedStore>(), koin.get<UserPreferences>())
         SingletonImageLoader.setSafe { context ->
             ImageLoader
                 .Builder(context)

app/src/main/kotlin/com/subtracks/data/prefs/UserPreferences.kt

@@ -4,10 +4,12 @@ import android.content.Context
 import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.intPreferencesKey
 import androidx.datastore.preferences.core.stringPreferencesKey
 import androidx.datastore.preferences.preferencesDataStore
 import com.subtracks.data.net.NetworkMode
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.map
 
 enum class AlbumSort { Name, Artist, Year, Added, Starred }
@@ -43,6 +45,12 @@ data class StreamQuality(
 
 private val Context.preferences: DataStore<Preferences> by preferencesDataStore("user_prefs")
 
+data class ArtworkSeedValue(
+    val cacheKey: String,
+    val primary: Int,
+    val secondary: Int?,
+)
+
 class UserPreferences(
     private val store: DataStore<Preferences>,
 ) {
@@ -69,6 +77,25 @@ class UserPreferences(
 
     private fun streamQualityKey(mode: NetworkMode) = stringPreferencesKey("stream_quality_${mode.key}")
 
+    suspend fun lastSeed(): ArtworkSeedValue? {
+        val prefs = store.data.first()
+        val cacheKey = prefs[lastSeedKey] ?: return null
+        val primary = prefs[lastSeedPrimary] ?: return null
+        return ArtworkSeedValue(cacheKey, primary, prefs[lastSeedSecondary])
+    }
+
+    suspend fun setLastSeed(value: ArtworkSeedValue) {
+        store.edit { prefs ->
+            prefs[lastSeedKey] = value.cacheKey
+            prefs[lastSeedPrimary] = value.primary
+            if (value.secondary != null) prefs[lastSeedSecondary] = value.secondary else prefs.remove(lastSeedSecondary)
+        }
+    }
+
+    private val lastSeedKey = stringPreferencesKey("last_seed_key")
+    private val lastSeedPrimary = intPreferencesKey("last_seed_primary")
+    private val lastSeedSecondary = intPreferencesKey("last_seed_secondary")
+
     private fun listQueryKey(tab: LibraryListTab) = stringPreferencesKey("list_query_${tab.key}")
 
     private fun encode(query: ListQuery) = "${query.sort}|${if (query.descending) 1 else 0}|${query.starred.ordinal}"

app/src/main/kotlin/com/subtracks/ui/AppRoot.kt

@@ -4,8 +4,10 @@ import android.net.Uri
 import androidx.activity.OnBackPressedCallback
 import androidx.activity.compose.LocalOnBackPressedDispatcherOwner
 import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.EnterTransition
 import androidx.compose.animation.core.animate
 import androidx.compose.animation.core.animateDpAsState
+import androidx.compose.animation.core.snap
 import androidx.compose.animation.core.tween
 import androidx.compose.animation.expandVertically
 import androidx.compose.animation.fadeIn
@@ -231,13 +233,16 @@ private fun MainNavigation() {
     val navBarInset = with(density) { WindowInsets.navigationBars.getBottom(this).toDp() }
     val keyboardUp = WindowInsets.imeAnimationTarget.getBottom(density) > 0
     val showMiniPlayer = playerVisible && !keyboardUp
+    var miniPlayerRevealed by remember { mutableStateOf(false) }
+    val firstReveal = !miniPlayerRevealed && showMiniPlayer
+    LaunchedEffect(showMiniPlayer) { if (showMiniPlayer) miniPlayerRevealed = true }
     val bottomInset by animateDpAsState(
         targetValue = if (showMiniPlayer) 0.dp else navBarInset,
-        animationSpec = tween(MINI_PLAYER_ANIM_MS),
+        animationSpec = if (firstReveal) snap() else tween(MINI_PLAYER_ANIM_MS),
         label = "libraryBottomInset",
     )
 
-    val artwork = rememberArtworkColors(playbackController.coverArt(playback.item, thumbnail = true))
+    val artwork = rememberArtworkColors(playbackController.coverArt(playback.item, thumbnail = true), markActive = true)
     ArtworkTheme(artwork) {
         Box(Modifier.fillMaxSize()) {
             Column(Modifier.fillMaxSize().imePadding()) {
@@ -376,7 +381,12 @@ private fun MainNavigation() {
 
                 AnimatedVisibility(
                     visible = showMiniPlayer,
-                    enter = expandVertically(tween(MINI_PLAYER_ANIM_MS), expandFrom = Alignment.Bottom),
+                    enter =
+                        if (firstReveal) {
+                            EnterTransition.None
+                        } else {
+                            expandVertically(tween(MINI_PLAYER_ANIM_MS), expandFrom = Alignment.Bottom)
+                        },
                     exit = shrinkVertically(tween(MINI_PLAYER_ANIM_MS), shrinkTowards = Alignment.Bottom),
                 ) {
                     val positionMs by playbackController.positionMs.collectAsStateWithLifecycle()

app/src/main/kotlin/com/subtracks/ui/theme/AnimatedArtworkColors.kt

@@ -38,10 +38,15 @@ fun rememberAnimatedArtworkColors(
     LaunchedEffect(target, durationMillis) {
         val next = target ?: baseArtworkColors
         if (next !== to) {
-            from = lerpArtworkColors(from, to, progress.value)
-            to = next
-            progress.snapTo(0f)
-            progress.animateTo(1f, tween(durationMillis = durationMillis))
+            if (to === baseArtworkColors) {
+                from = next
+                to = next
+            } else {
+                from = lerpArtworkColors(from, to, progress.value)
+                to = next
+                progress.snapTo(0f)
+                progress.animateTo(1f, tween(durationMillis = durationMillis))
+            }
         }
     }
 

app/src/main/kotlin/com/subtracks/ui/theme/ArtworkSeedCache.kt

@@ -21,6 +21,8 @@ import coil3.request.allowHardware
 import coil3.toBitmap
 import com.subtracks.data.model.ArtworkSeed
 import com.subtracks.data.model.CoverArtRef
+import com.subtracks.data.prefs.ArtworkSeedValue
+import com.subtracks.data.prefs.UserPreferences
 import com.subtracks.data.repo.ArtworkSeedStore
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
@@ -56,11 +58,38 @@ object ArtworkSeedCache {
     @Volatile
     private var store: ArtworkSeedStore? = null
 
-    fun install(store: ArtworkSeedStore?) {
+    @Volatile
+    private var prefs: UserPreferences? = null
+
+    @Volatile
+    private var lastSeed: ArtworkSeedValue? = null
+
+    fun install(
+        store: ArtworkSeedStore?,
+        prefs: UserPreferences? = null,
+    ) {
         this.store = store
+        this.prefs = prefs
+        if (prefs == null) {
+            lastSeed = null
+            return
+        }
+        scope.launch {
+            ignoreFailure { prefs.lastSeed() }?.let { lastSeed = it }
+        }
     }
 
-    fun cached(cacheKey: String): Pair<Int, Int?>? = cache.get(cacheKey)?.let { it.primary to it.secondary }
+    fun cached(cacheKey: String): Pair<Int, Int?>? =
+        cache.get(cacheKey)?.let { it.primary to it.secondary }
+            ?: lastSeed?.takeIf { it.cacheKey == cacheKey }?.let { it.primary to it.secondary }
+
+    fun markLast(ref: CoverArtRef) {
+        val prefs = prefs ?: return
+        val seed = cache.get(ref.cacheKey) ?: return
+        val value = ArtworkSeedValue(ref.cacheKey, seed.primary, seed.secondary)
+        lastSeed = value
+        scope.launch { ignoreFailure { prefs.setLastSeed(value) } }
+    }
 
     fun cachedBusy(cacheKey: String): Boolean? = cache.get(cacheKey)?.busy
 

app/src/main/kotlin/com/subtracks/ui/theme/ArtworkTheme.kt

@@ -6,6 +6,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.darkColorScheme
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.State
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.produceState
@@ -182,10 +183,16 @@ private fun blendHue(
 fun rememberArtworkColors(
     ref: CoverArtRef?,
     durationMillis: Int = ARTWORK_THEME_TRANSITION_MS,
+    markActive: Boolean = false,
 ): ArtworkColors? {
     val cached = remember(ref?.cacheKey) { ref?.cacheKey?.let(ArtworkSeedCache::cached) }
     val seeds by rememberArtworkSeed(ref)
     val effective = seeds ?: cached
+    if (markActive) {
+        LaunchedEffect(ref?.cacheKey, effective) {
+            if (ref != null && effective != null) ArtworkSeedCache.markLast(ref)
+        }
+    }
     val target = remember(effective) { effective?.let { (primary, secondary) -> artworkColorsFromSeeds(primary, secondary) } }
     val colors = rememberAnimatedArtworkColors(target, durationMillis)
     return if (target == null) null else colors

app/src/test/kotlin/com/subtracks/data/prefs/UserPreferencesTest.kt

@@ -55,6 +55,27 @@ class UserPreferencesTest {
             assertEquals(StreamQuality(320, null), prefs.streamQuality(NetworkMode.Wifi).first())
             assertEquals(StreamQuality(96, "opus"), prefs.streamQuality(NetworkMode.Mobile).first())
 
+            file.delete()
+        }
+
+    @Test
+    fun lastSeedRoundTripsWithAndWithoutASecondary() =
+        runTest {
+            val file = File.createTempFile("user-prefs", ".preferences_pb").apply { delete() }
+            val store = PreferenceDataStoreFactory.create(scope = backgroundScope) { file }
+            val prefs = UserPreferences(store)
+
+            assertEquals(null, prefs.lastSeed())
+
+            prefs.setLastSeed(ArtworkSeedValue("art:1", 0xFF112233.toInt(), 0xFF445566.toInt()))
+            assertEquals(
+                ArtworkSeedValue("art:1", 0xFF112233.toInt(), 0xFF445566.toInt()),
+                prefs.lastSeed(),
+            )
+
+            prefs.setLastSeed(ArtworkSeedValue("art:2", 0xFF778899.toInt(), null))
+            assertEquals(ArtworkSeedValue("art:2", 0xFF778899.toInt(), null), prefs.lastSeed())
+
             file.delete()
         }
 }

app/src/test/kotlin/com/subtracks/ui/theme/ArtworkExtractionTest.kt

@@ -6,6 +6,7 @@ import android.graphics.Color
 import androidx.activity.ComponentActivity
 import androidx.compose.material3.Text
 import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.SideEffect
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.ui.graphics.luminance
@@ -92,6 +93,24 @@ class ArtworkExtractionTest {
         assertEquals(42, state.value)
     }
 
+    @Test
+    fun theFirstArtworkColourAppearsWithoutFadingFromTheBaseScheme() {
+        val target = artworkColorsFromSeed(0xFF3A7BD5.toInt())
+        val artwork = mutableStateOf<ArtworkColors?>(null)
+        val seen = mutableListOf<androidx.compose.ui.graphics.Color>()
+        composeRule.setContent {
+            val colors = rememberAnimatedArtworkColors(artwork.value)
+            SideEffect { seen += colors.scheme.background }
+        }
+        composeRule.waitForIdle()
+
+        composeRule.runOnIdle { artwork.value = target }
+        composeRule.waitForIdle()
+
+        val firstPainting = seen.first { it != baseArtworkColors.scheme.background }
+        assertEquals(target.scheme.background, firstPainting)
+    }
+
     @Test
     fun keepsTheStoredSeedWhenTheArtCannotBeDecoded() {
         val key = "missing-${System.nanoTime()}"