replace the play arrow with an animated bar indicator

Three equaliser bars wave with staggered phases to draw the eye to the
playing track, keeping the soft shadow over cover art and flat bars in
the queue.

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

@@ -1,5 +1,10 @@
 package com.subtracks.ui.library
 
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.infiniteRepeatable
+import androidx.compose.animation.core.rememberInfiniteTransition
+import androidx.compose.animation.core.tween
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.border
 import androidx.compose.foundation.layout.Arrangement
@@ -13,7 +18,6 @@ import androidx.compose.foundation.text.BasicText
 import androidx.compose.foundation.text.TextAutoSize
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.rounded.DownloadDone
-import androidx.compose.material.icons.rounded.PlayArrow
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.Icon
 import androidx.compose.material3.ListItem
@@ -21,6 +25,7 @@ import androidx.compose.material3.ListItemDefaults
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -36,13 +41,8 @@ import androidx.compose.ui.graphics.asAndroidPath
 import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.graphics.drawscope.clipPath
 import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
-import androidx.compose.ui.graphics.drawscope.withTransform
 import androidx.compose.ui.graphics.nativeCanvas
 import androidx.compose.ui.graphics.toArgb
-import androidx.compose.ui.graphics.vector.ImageVector
-import androidx.compose.ui.graphics.vector.PathParser
-import androidx.compose.ui.graphics.vector.VectorGroup
-import androidx.compose.ui.graphics.vector.VectorPath
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.semantics.contentDescription
 import androidx.compose.ui.semantics.semantics
@@ -56,6 +56,8 @@ import com.subtracks.data.model.DownloadStatus
 import com.subtracks.data.model.Song
 import com.subtracks.data.model.SongDownload
 import com.subtracks.ui.components.CoverArt
+import kotlin.math.PI
+import kotlin.math.sin
 
 private val TRACK_COLUMN_WIDTH = 24.dp
 private val TIME_COLUMN_WIDTH = 36.dp
@@ -66,23 +68,9 @@ private val PLAY_SHADOW_RADIUS = 3.dp
 private val PLAY_SHADOW = Color.Black.copy(alpha = 0.6f)
 private val INNER_SHADOW_RADIUS = 8.dp
 private val INNER_SHADOW = Color.Black.copy(alpha = 0.85f)
-private val PLAY_ARROW = Icons.Rounded.PlayArrow
-private val PLAY_ARROW_PATH: Path by lazy { buildVectorPath(PLAY_ARROW) }
-
-private fun buildVectorPath(vector: ImageVector): Path {
-    val parser = PathParser()
-
-    fun collect(group: VectorGroup) {
-        for (node in group) {
-            when (node) {
-                is VectorPath -> parser.addPathNodes(node.pathData)
-                is VectorGroup -> collect(node)
-            }
-        }
-    }
-    collect(vector.root)
-    return parser.toPath()
-}
+private const val BAR_COUNT = 3
+private const val PLAY_BAR_PERIOD_MS = 900
+private const val PLAY_BAR_PHASE = 0.18f
 
 @Composable
 fun SongRow(
@@ -216,30 +204,44 @@ private fun PlayIndicator(
     shadow: Boolean,
     modifier: Modifier = Modifier,
 ) {
+    val phase by
+        rememberInfiniteTransition(label = "playing")
+            .animateFloat(
+                initialValue = 0f,
+                targetValue = 1f,
+                animationSpec = infiniteRepeatable(tween(PLAY_BAR_PERIOD_MS, easing = LinearEasing)),
+                label = "phase",
+            )
     val tint = MaterialTheme.colorScheme.primary
-    if (shadow) {
-        val radius = with(LocalDensity.current) { PLAY_SHADOW_RADIUS.toPx() }
-        Canvas(modifier.semantics { contentDescription = "Playing" }) {
-            val scale = minOf(size.width / PLAY_ARROW.viewportWidth, size.height / PLAY_ARROW.viewportHeight)
-            withTransform({ scale(scale, scale, pivot = Offset.Zero) }) {
-                drawIntoCanvas { canvas ->
-                    val paint =
-                        android.graphics.Paint().apply {
-                            isAntiAlias = true
-                            color = tint.toArgb()
-                            setShadowLayer(radius, 0f, 0f, PLAY_SHADOW.toArgb())
-                        }
-                    canvas.nativeCanvas.drawPath(PLAY_ARROW_PATH.asAndroidPath(), paint)
-                }
+    val shadowRadius = with(LocalDensity.current) { PLAY_SHADOW_RADIUS.toPx() }
+    Canvas(modifier.semantics { contentDescription = "Playing" }) {
+        val barWidth = size.width * 0.22f
+        val gap = size.width * 0.11f
+        val radius = CornerRadius(barWidth / 2f)
+        val total = barWidth * BAR_COUNT + gap * (BAR_COUNT - 1)
+        val startX = (size.width - total) / 2f
+        val minHeight = size.height * 0.3f
+        val bars =
+            (0 until BAR_COUNT).map { index ->
+                val wave = ((sin((phase + index * PLAY_BAR_PHASE) * 2.0 * PI) + 1.0) / 2.0).toFloat()
+                val height = minHeight + (size.height - minHeight) * wave
+                val x = startX + index * (barWidth + gap)
+                Rect(x, (size.height - height) / 2f, x + barWidth, (size.height + height) / 2f)
             }
+        if (shadow) {
+            val path = Path().apply { bars.forEach { addRoundRect(RoundRect(it, radius)) } }
+            drawIntoCanvas { canvas ->
+                val paint =
+                    android.graphics.Paint().apply {
+                        isAntiAlias = true
+                        color = tint.toArgb()
+                        setShadowLayer(shadowRadius, 0f, 0f, PLAY_SHADOW.toArgb())
+                    }
+                canvas.nativeCanvas.drawPath(path.asAndroidPath(), paint)
+            }
+        } else {
+            bars.forEach { drawRoundRect(color = tint, topLeft = it.topLeft, size = it.size, cornerRadius = radius) }
         }
-    } else {
-        Icon(
-            imageVector = PLAY_ARROW,
-            contentDescription = "Playing",
-            tint = tint,
-            modifier = modifier,
-        )
     }
 }