Change inner card style

ui/src/main/java/de/mm20/launcher2/ui/component/InnerCard.kt

@@ -2,17 +2,30 @@ package de.mm20.launcher2.ui.component
 
 import androidx.compose.animation.animateColor
 import androidx.compose.animation.core.animateDp
+import androidx.compose.animation.core.animateFloat
 import androidx.compose.animation.core.tween
 import androidx.compose.animation.core.updateTransition
 import androidx.compose.foundation.BorderStroke
+import androidx.compose.foundation.border
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.ColorScheme
+import androidx.compose.material3.LocalAbsoluteTonalElevation
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.draw.drawBehind
+import androidx.compose.ui.draw.shadow
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.compositeOver
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import de.mm20.launcher2.ui.locals.LocalCardStyle
+import kotlin.math.ln
 
 @Composable
 fun InnerCard(
@@ -22,6 +35,8 @@ fun InnerCard(
 ) {
     val transition = updateTransition(raised, label = "InnerCard")
 
+    val absoluteTonalElevation = LocalAbsoluteTonalElevation.current
+
     val elevation by transition.animateDp(label = "elevation", transitionSpec = {
         tween(250, if (targetState) 250 else 0)
     }) {
@@ -32,15 +47,42 @@ fun InnerCard(
         if (it) 0.dp else 1.dp
     }
     val borderColor by transition.animateColor(label = "borderColor", transitionSpec = { tween(500) }) {
-        MaterialTheme.colorScheme.surfaceVariant.copy(alpha = if (it) 0f else 1f)
+        MaterialTheme.colorScheme.outline.copy(alpha = if (it) 0f else 0.17f)
+    }
+    val bgAlpha by transition.animateFloat(label = "bgAlpha", transitionSpec = {
+        tween(250, if (targetState) 0 else 250)
+    }) {
+        if (it) 1f else 0f
     }
 
-    Surface(
-        shadowElevation = elevation,
-        tonalElevation = elevation,
-        shape = RoundedCornerShape(LocalCardStyle.current.radius.dp),
-        border = BorderStroke(borderWidth, borderColor),
-        content = content,
+    val shape = RoundedCornerShape(LocalCardStyle.current.radius.dp)
+
+    val bgColor = MaterialTheme.colorScheme.surfaceColorAtElevation(absoluteTonalElevation + elevation)
+
+    Box(
         modifier = modifier
-    )
+            .border(BorderStroke(borderWidth, borderColor), shape)
+            .shadow(elevation, shape, clip = false)
+            .clip(shape)
+            .drawBehind {
+                drawRect(
+                    bgColor.copy(alpha = bgAlpha)
+                )
+            }
+        ,
+    ) {
+        CompositionLocalProvider(
+            LocalAbsoluteTonalElevation provides absoluteTonalElevation
+        ) {
+            content()
+        }
+    }
+}
+
+internal fun ColorScheme.surfaceColorAtElevation(
+    elevation: Dp,
+): Color {
+    if (elevation == 0.dp) return surface
+    val alpha = ((4.5f * ln(elevation.value + 1)) + 2f) / 100f
+    return surfaceTint.copy(alpha = alpha).compositeOver(surface)
 }