polish the album hero: bigger art, fading title bar, art-faithful colours

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

@@ -1,19 +1,27 @@
 package com.subtracks.ui.library
 
+import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxWithConstraints
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.WindowInsets
+import androidx.compose.foundation.layout.aspectRatio
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.statusBars
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.rounded.ArrowBack
@@ -23,6 +31,7 @@ import androidx.compose.material.icons.rounded.PlayArrow
 import androidx.compose.material.icons.rounded.Shuffle
 import androidx.compose.material3.Button
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FilledIconButton
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.LocalContentColor
@@ -33,13 +42,21 @@ import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.layout.onSizeChanged
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.subtracks.data.model.Album
@@ -55,9 +72,12 @@ import com.subtracks.ui.theme.rememberArtworkColors
 import org.koin.compose.koinInject
 import org.koin.compose.viewmodel.koinViewModel
 import org.koin.core.parameter.parametersOf
+import kotlin.math.roundToInt
 
-private val ART_SIZE = 240.dp
 private const val DOT = "\u00B7"
+private const val GRADIENT_SCREENS = 1.5f
+private const val FADE_DISTANCE_DP = 96
+private const val CONTROLS_BLOCK_DP = 64
 
 @Composable
 fun AlbumDetailRoute(
@@ -98,23 +118,73 @@ fun AlbumDetailScreen(
 ) {
     ArtworkTheme(artwork) {
         CompositionLocalProvider(LocalContentColor provides MaterialTheme.colorScheme.onBackground) {
-            Box(modifier.fillMaxSize()) {
-                HeroGradient(artwork, Modifier.fillMaxSize())
+            BoxWithConstraints(modifier.fillMaxSize().background(Color.Black)) {
+                val listState = rememberLazyListState()
+                val density = LocalDensity.current
+                val statusBarTop = WindowInsets.statusBars.getTop(density)
+                val barHeightPx = statusBarTop + with(density) { TopAppBarDefaults.TopAppBarExpandedHeight.toPx() }
+                val controlsBlockPx = with(density) { CONTROLS_BLOCK_DP.dp.toPx() }
+                val fadeDistancePx = with(density) { FADE_DISTANCE_DP.dp.toPx() }
+
+                var headerHeightPx by remember { mutableFloatStateOf(0f) }
+                var rowHeightPx by remember { mutableFloatStateOf(0f) }
+                val scrollPx by remember {
+                    derivedStateOf {
+                        val index = listState.firstVisibleItemIndex
+                        val before = if (index <= 0) 0f else headerHeightPx + rowHeightPx * (index - 1)
+                        (before + listState.firstVisibleItemScrollOffset).coerceAtLeast(0f)
+                    }
+                }
+                val barFraction by remember {
+                    derivedStateOf {
+                        if (headerHeightPx == 0f) {
+                            0f
+                        } else {
+                            val end = headerHeightPx - controlsBlockPx - barHeightPx
+                            val start = end - fadeDistancePx
+                            ((scrollPx - start) / (end - start)).coerceIn(0f, 1f)
+                        }
+                    }
+                }
+                val gradientAlpha by animateFloatAsState(
+                    targetValue = if (artwork != null) 1f else 0f,
+                    animationSpec = tween(durationMillis = 600),
+                    label = "gradientAlpha",
+                )
+
+                HeroGradient(
+                    colors = artwork,
+                    modifier =
+                        Modifier
+                            .fillMaxWidth()
+                            .height(maxHeight * GRADIENT_SCREENS)
+                            .offset { IntOffset(0, -scrollPx.roundToInt()) }
+                            .alpha(gradientAlpha),
+                )
+
                 Scaffold(
                     containerColor = Color.Transparent,
                     topBar = {
                         TopAppBar(
-                            title = {},
+                            title = {
+                                Text(
+                                    text = album?.name.orEmpty(),
+                                    maxLines = 1,
+                                    overflow = TextOverflow.Ellipsis,
+                                    modifier = Modifier.alpha(barFraction),
+                                )
+                            },
                             navigationIcon = {
-                                IconButton(onClick = onBack) {
+                                IconButton(onClick = onBack, modifier = Modifier.alpha(barFraction)) {
                                     Icon(Icons.AutoMirrored.Rounded.ArrowBack, contentDescription = "Back")
                                 }
                             },
                             colors = TopAppBarDefaults.topAppBarColors(containerColor = Color.Transparent),
+                            modifier = Modifier.background(Color.Black.copy(alpha = barFraction)),
                         )
                     },
                 ) { padding ->
-                    LazyColumn(Modifier.padding(padding).fillMaxSize()) {
+                    LazyColumn(state = listState, modifier = Modifier.padding(padding).fillMaxSize()) {
                         item {
                             AlbumHeader(
                                 album = album,
@@ -124,13 +194,17 @@ fun AlbumDetailScreen(
                                 onShuffle = onShuffle,
                                 onDownload = onDownload,
                                 onMore = onMore,
+                                modifier = Modifier.onSizeChanged { headerHeightPx = it.height.toFloat() },
                             )
                         }
                         itemsIndexed(songs, key = { _, song -> song.id }) { index, song ->
                             SongRow(
                                 song = song,
                                 isPlaying = song.id == playingSongId,
-                                modifier = Modifier.clickable { onSongClick(index) },
+                                modifier =
+                                    Modifier
+                                        .onSizeChanged { rowHeightPx = it.height.toFloat() }
+                                        .clickable { onSongClick(index) },
                             )
                         }
                     }
@@ -149,15 +223,16 @@ private fun AlbumHeader(
     onShuffle: () -> Unit,
     onDownload: () -> Unit,
     onMore: () -> Unit,
+    modifier: Modifier = Modifier,
 ) {
     Column(
-        modifier = Modifier.fillMaxWidth().padding(horizontal = 24.dp, vertical = 16.dp),
+        modifier = modifier.fillMaxWidth().padding(horizontal = 24.dp, vertical = 16.dp),
         horizontalAlignment = Alignment.CenterHorizontally,
     ) {
         CoverArt(
             ref = coverArt(album?.coverArt, false),
             name = album?.name.orEmpty(),
-            modifier = Modifier.size(ART_SIZE).clip(RoundedCornerShape(8.dp)),
+            modifier = Modifier.fillMaxWidth(0.78f).aspectRatio(1f).clip(RoundedCornerShape(2.dp)),
         )
         Spacer(Modifier.height(20.dp))
         Text(
@@ -196,7 +271,7 @@ private fun AlbumHeader(
                 Spacer(Modifier.width(8.dp))
                 Text("Play")
             }
-            IconButton(onClick = onShuffle, enabled = hasSongs) {
+            FilledIconButton(onClick = onShuffle, enabled = hasSongs) {
                 Icon(Icons.Rounded.Shuffle, contentDescription = "Shuffle play")
             }
             IconButton(onClick = onMore) {

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

@@ -27,6 +27,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 
 private const val SEED_ART_SIZE_PX = 128
+private const val GRADIENT_FADE_START = 0.8f / 1.5f
 
 data class ArtworkColors(
     val scheme: ColorScheme,
@@ -37,54 +38,53 @@ data class ArtworkColors(
 
 fun artworkColorsFromSeed(seed: Int): ArtworkColors {
     val (hue, saturation, _) = Color(seed or 0xFF000000.toInt()).toHsl()
-    val chroma = saturation.coerceIn(0.30f, 0.72f)
-    val secondaryHue = (hue + 60f) % 360f
+    val s = saturation.coerceAtMost(0.85f)
 
     fun tone(
         h: Float,
-        s: Float,
+        sat: Float,
         l: Float,
-    ) = Color.hsl(h % 360f, s.coerceIn(0f, 1f), l.coerceIn(0f, 1f))
+    ) = Color.hsl(h % 360f, sat.coerceIn(0f, 1f), l.coerceIn(0f, 1f))
 
-    val primary = tone(hue, chroma, 0.80f)
-    val background = tone(hue, (saturation * 0.7f).coerceIn(0.06f, 0.22f), 0.06f)
-    val onBackground = tone(hue, 0.08f, 0.95f)
+    val primary = tone(hue, s, 0.62f)
+    val background = tone(hue, (s * 0.35f).coerceAtMost(0.20f), 0.06f)
+    val onBackground = tone(hue, (s * 0.10f).coerceAtMost(0.08f), 0.95f)
 
     val scheme =
         darkColorScheme(
             primary = primary,
-            onPrimary = tone(hue, chroma * 0.6f, 0.14f),
-            primaryContainer = tone(hue, chroma, 0.32f),
-            onPrimaryContainer = tone(hue, chroma * 0.5f, 0.92f),
-            secondary = tone(hue, chroma * 0.5f, 0.78f),
-            onSecondary = tone(hue, chroma * 0.4f, 0.14f),
-            secondaryContainer = tone(hue, chroma * 0.45f, 0.30f),
-            onSecondaryContainer = tone(hue, chroma * 0.4f, 0.90f),
-            tertiary = tone(secondaryHue, chroma, 0.80f),
-            onTertiary = tone(secondaryHue, chroma * 0.6f, 0.14f),
-            tertiaryContainer = tone(secondaryHue, chroma, 0.30f),
-            onTertiaryContainer = tone(secondaryHue, chroma * 0.5f, 0.90f),
+            onPrimary = tone(hue, s * 0.6f, 0.12f),
+            primaryContainer = tone(hue, s, 0.28f),
+            onPrimaryContainer = tone(hue, s * 0.7f, 0.92f),
+            secondary = tone(hue, s * 0.6f, 0.66f),
+            onSecondary = tone(hue, s * 0.5f, 0.12f),
+            secondaryContainer = tone(hue, s * 0.55f, 0.26f),
+            onSecondaryContainer = tone(hue, s * 0.5f, 0.90f),
+            tertiary = tone(hue, s * 0.9f, 0.72f),
+            onTertiary = tone(hue, s * 0.6f, 0.12f),
+            tertiaryContainer = tone(hue, s * 0.8f, 0.28f),
+            onTertiaryContainer = tone(hue, s * 0.6f, 0.90f),
             background = background,
             onBackground = onBackground,
             surface = background,
             onSurface = onBackground,
             surfaceTint = primary,
-            surfaceVariant = tone(hue, 0.15f, 0.17f),
-            onSurfaceVariant = tone(hue, 0.12f, 0.78f),
-            surfaceContainerLowest = tone(hue, 0.16f, 0.04f),
-            surfaceContainerLow = tone(hue, 0.16f, 0.08f),
-            surfaceContainer = tone(hue, 0.16f, 0.10f),
-            surfaceContainerHigh = tone(hue, 0.15f, 0.14f),
-            surfaceContainerHighest = tone(hue, 0.14f, 0.18f),
-            outline = tone(hue, 0.10f, 0.55f),
-            outlineVariant = tone(hue, 0.12f, 0.28f),
+            surfaceVariant = tone(hue, s * 0.25f, 0.17f),
+            onSurfaceVariant = tone(hue, s * 0.18f, 0.78f),
+            surfaceContainerLowest = tone(hue, s * 0.25f, 0.04f),
+            surfaceContainerLow = tone(hue, s * 0.25f, 0.08f),
+            surfaceContainer = tone(hue, s * 0.25f, 0.10f),
+            surfaceContainerHigh = tone(hue, s * 0.22f, 0.14f),
+            surfaceContainerHighest = tone(hue, s * 0.20f, 0.18f),
+            outline = tone(hue, s * 0.15f, 0.55f),
+            outlineVariant = tone(hue, s * 0.18f, 0.28f),
         )
 
     return ArtworkColors(
         scheme = scheme,
-        gradientHigh = tone(hue, (saturation * 0.9f).coerceIn(0.30f, 0.60f), 0.24f),
-        gradientLow = tone(hue, 0.12f, 0.04f),
-        accents = listOf(tone(hue, chroma, 0.60f), tone(secondaryHue, chroma, 0.55f)),
+        gradientHigh = tone(hue, (s * 0.7f).coerceAtMost(0.55f), 0.25f),
+        gradientLow = tone(hue, s * 0.20f, 0.04f),
+        accents = listOf(tone(hue, s, 0.55f), tone(hue, s * 0.7f, 0.42f)),
     )
 }
 
@@ -169,9 +169,9 @@ fun HeroGradient(
             drawRect(
                 brush =
                     Brush.radialGradient(
-                        colors = listOf(accent.copy(alpha = 0.35f), accent.copy(alpha = 0f)),
-                        center = Offset(size.width * 0.15f, size.height * 0.08f),
-                        radius = size.width * 0.95f,
+                        colors = listOf(accent.copy(alpha = 0.40f), accent.copy(alpha = 0f)),
+                        center = Offset(size.width * 0.15f, size.height * 0.06f),
+                        radius = size.width * 0.85f,
                     ),
             )
         }
@@ -179,9 +179,9 @@ fun HeroGradient(
             drawRect(
                 brush =
                     Brush.radialGradient(
-                        colors = listOf(accent.copy(alpha = 0.30f), accent.copy(alpha = 0f)),
-                        center = Offset(size.width * 0.95f, size.height * 0.35f),
-                        radius = size.width * 0.9f,
+                        colors = listOf(accent.copy(alpha = 0.32f), accent.copy(alpha = 0f)),
+                        center = Offset(size.width * 0.90f, size.height * 0.24f),
+                        radius = size.width * 0.80f,
                     ),
             )
         }
@@ -189,8 +189,19 @@ fun HeroGradient(
             brush =
                 Brush.radialGradient(
                     colors = listOf(high.copy(alpha = 0.45f), high.copy(alpha = 0f)),
-                    center = Offset(size.width * 0.55f, size.height * 0.85f),
-                    radius = size.width * 1.1f,
+                    center = Offset(size.width * 0.55f, size.height * 0.45f),
+                    radius = size.width * 0.90f,
+                ),
+        )
+        drawRect(
+            brush =
+                Brush.verticalGradient(
+                    colorStops =
+                        arrayOf(
+                            0f to Color.Transparent,
+                            GRADIENT_FADE_START to Color.Transparent,
+                            1f to Color.Black,
+                        ),
                 ),
         )
     }