Sin based lazy layout

SineLayout.kt

package io.github.fourlastor.keys.lazylayout

import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.ScrollState
import androidx.compose.foundation.checkScrollableContainerConstraints
import androidx.compose.foundation.clipScrollableContainer
import androidx.compose.foundation.gestures.Orientation
import androidx.compose.foundation.gestures.scrollable
import androidx.compose.foundation.lazy.layout.LazyLayout
import androidx.compose.foundation.lazy.layout.LazyLayoutItemProvider
import androidx.compose.foundation.lazy.layout.LazyLayoutMeasureScope
import androidx.compose.foundation.rememberScrollState
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.layout.MeasureResult
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.sp
import kotlin.math.sin

@Preview
@OptIn(ExperimentalFoundationApi::class)
@Composable
fun SineLayout() {
  val scrollState = rememberScrollState()
  val itemProvider = CustomItemProvider()
  LazyLayout(
    modifier = Modifier
      .clipScrollableContainer(Orientation.Vertical) // used to enforce finite constraints and still have scrollable content
      .scrollable(state = scrollState, orientation = Orientation.Vertical),
    itemProvider = itemProvider,
    measurePolicy = rememberMeasurePolicy(scrollState, itemProvider)
  )
}

@OptIn(ExperimentalFoundationApi::class)
@Composable
private fun rememberMeasurePolicy(scrollState: ScrollState, itemProvider: LazyLayoutItemProvider): LazyLayoutMeasureScope.(Constraints) -> MeasureResult =
  remember {
    { constraints ->
      // ensure that the max height isn't infinite
      checkScrollableContainerConstraints(constraints, Orientation.Vertical)

      // measure all children
      val placeables = sequence {
        for (i in 0 until itemProvider.itemCount) {
          yieldAll(measure(i, constraints).iterator())
        }
      }.toList()


      // layout all children until we run out of space
      layout(constraints.maxWidth, constraints.maxHeight) {
        var y = 0
        var i = 0
        while (y < constraints.maxHeight && i < placeables.size) {
          val placeable = placeables[i]
          val factor = (sin(y.toDouble()) + 1) / 2
          val x = ((factor * constraints.maxWidth * 0.6) + 0.2 * constraints.maxWidth).toInt()
          placeable.placeRelative(x, y)
          y += placeable.height
          i++
        }
      }
    }
  }

@OptIn(ExperimentalFoundationApi::class)
class CustomItemProvider : LazyLayoutItemProvider {
  override val itemCount: Int
    get() = 500

  @Composable
  override fun Item(index: Int) {
    Text(text = "$index", fontSize = 44.sp)
  }
}