sample the bar colour from the gradient, saturate the accents

app/src/main/kotlin/com/subtracks/ui/library/AlbumDetailScreen.kt

@@ -78,6 +78,7 @@ import com.subtracks.ui.components.rememberViewportFill
 import com.subtracks.ui.theme.ArtworkColors
 import com.subtracks.ui.theme.ArtworkTheme
 import com.subtracks.ui.theme.HeroGradient
+import com.subtracks.ui.theme.gradientColorAt
 import com.subtracks.ui.theme.rememberArtworkColors
 import org.koin.compose.koinInject
 import org.koin.compose.viewmodel.koinViewModel
@@ -130,8 +131,9 @@ fun AlbumDetailScreen(
             BoxWithConstraints(modifier.fillMaxSize().background(Color.Black)) {
                 val listState = rememberLazyListState()
                 val fill = rememberViewportFill(listState)
-                val gradientHeight = maxHeight * GRADIENT_SCREENS
                 val density = LocalDensity.current
+                val gradientHeight = maxHeight * GRADIENT_SCREENS
+                val gradientHeightPx = with(density) { gradientHeight.toPx() }
                 val statusBarTop = WindowInsets.statusBars.getTop(density)
                 val navBarBottom = WindowInsets.navigationBars.getBottom(density)
                 val statusBarDp = with(density) { statusBarTop.toDp() }
@@ -162,6 +164,9 @@ fun AlbumDetailScreen(
                     animationSpec = tween(durationMillis = 600),
                     label = "gradientAlpha",
                 )
+                val barColor =
+                    artwork?.gradientColorAt(((scrollPx + barHeightPx / 2f) / gradientHeightPx).coerceIn(0f, 1f))
+                        ?: Color.Black
 
                 HeroGradient(
                     colors = artwork,
@@ -223,24 +228,6 @@ fun AlbumDetailScreen(
                         ).alpha(1f - barFraction),
                 )
 
-                Box(
-                    Modifier
-                        .align(Alignment.TopStart)
-                        .fillMaxWidth()
-                        .height(with(density) { barHeightPx.toDp() })
-                        .clipToBounds()
-                        .alpha(barFraction),
-                ) {
-                    HeroGradient(
-                        colors = artwork,
-                        modifier =
-                            Modifier
-                                .fillMaxWidth()
-                                .requiredHeight(gradientHeight)
-                                .offset { IntOffset(0, -scrollPx.roundToInt()) },
-                    )
-                }
-
                 TopAppBar(
                     title = {
                         Text(
@@ -260,6 +247,7 @@ fun AlbumDetailScreen(
                     modifier =
                         Modifier
                             .align(Alignment.TopStart)
+                            .background(barColor.copy(alpha = barFraction))
                             .clickable(
                                 interactionSource = remember { MutableInteractionSource() },
                                 indication = null,

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

@@ -14,6 +14,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Brush
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.lerp
 import androidx.compose.ui.graphics.luminance
 import androidx.palette.graphics.Palette
 import coil3.SingletonImageLoader
@@ -92,20 +93,39 @@ fun artworkColorsFromSeeds(
 
     val secondary =
         secondarySeed?.let { seed ->
-            val color = Color(seed or 0xFF000000.toInt())
-            val (sh, ss, sl) = color.toHsl()
-            if (sl > 0.55f) Color.hsl(sh, ss, 0.30f) else color
-        } ?: tone(hue, s, 0.08f)
+            val (sh, ss, sl) = Color(seed or 0xFF000000.toInt()).toHsl()
+            Color.hsl(
+                blendHue(sh, hue, 0.5f),
+                ss.coerceAtLeast(s * 0.7f).coerceAtMost(0.9f),
+                sl.coerceIn(0.34f, 0.56f),
+            )
+        } ?: tone(hue, s, 0.40f)
 
     return ArtworkColors(
         scheme = scheme,
-        gradientHigh = tone(hue, (s * 0.6f).coerceAtMost(0.50f), 0.22f),
-        gradientLow = tone(hue, s * 0.30f, 0.03f),
-        accents = listOf(tone(hue, s * 0.8f, 0.90f), secondary),
+        gradientHigh = tone(hue, (s * 0.85f).coerceAtMost(0.65f), 0.30f),
+        gradientLow = tone(hue, s * 0.45f, 0.04f),
+        accents = listOf(tone(hue, s, 0.72f), secondary),
         blobSeed = primarySeed,
     )
 }
 
+fun ArtworkColors.gradientColorAt(fraction: Float): Color {
+    val t = fraction.coerceIn(0f, 1f)
+    val base = lerp(gradientHigh, gradientLow, t)
+    val fade = ((t - GRADIENT_FADE_START) / (1f - GRADIENT_FADE_START)).coerceIn(0f, 1f)
+    return lerp(base, Color.Black, fade)
+}
+
+private fun blendHue(
+    from: Float,
+    to: Float,
+    fraction: Float,
+): Float {
+    val delta = ((to - from + 540f) % 360f) - 180f
+    return (from + delta * fraction + 360f) % 360f
+}
+
 @Composable
 fun rememberArtworkColors(ref: CoverArtRef?): ArtworkColors? {
     val seeds by rememberArtworkSeed(ref)