ScrollableColumn and LazyScrollableColumn for Compose for desktop

ScrollableColumn.jvm.kt

import androidx.compose.foundation.ScrollState
import androidx.compose.foundation.VerticalScrollbar
import androidx.compose.foundation.gestures.FlingBehavior
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.ColumnScope
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.LazyListScope
import androidx.compose.foundation.lazy.LazyListState
import androidx.compose.foundation.rememberScrollbarAdapter
import androidx.compose.foundation.verticalScroll
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.unit.Constraints
import kotlin.math.max

@Composable
actual fun ScrollableLazyColumnImpl(
    modifier: Modifier,
    state: LazyListState,
    contentPadding: PaddingValues,
    reverseLayout: Boolean,
    verticalArrangement: Arrangement.Vertical,
    horizontalAlignment: Alignment.Horizontal,
    flingBehavior: FlingBehavior,
    userScrollEnabled: Boolean,
    content: LazyListScope.() -> Unit
) {
    ScrollableWrapper(modifier) {
        LazyColumn(
            state = state,
            contentPadding = contentPadding,
            reverseLayout = reverseLayout,
            verticalArrangement = verticalArrangement,
            horizontalAlignment = horizontalAlignment,
            flingBehavior = flingBehavior,
            userScrollEnabled = userScrollEnabled,
            content = content,
        )
        VerticalScrollbar(adapter = rememberScrollbarAdapter(state))
    }
}

@Composable
actual fun ScrollableColumnImpl(
    modifier: Modifier,
    state: ScrollState,
    verticalArrangement: Arrangement.Vertical,
    horizontalAlignment: Alignment.Horizontal,
    contentPadding: PaddingValues,
    content: @Composable ColumnScope.() -> Unit
) {
    ScrollableWrapper(modifier) {
        Column(
            modifier = Modifier
                .padding(contentPadding)
                .verticalScroll(state),
            verticalArrangement = verticalArrangement,
            horizontalAlignment = horizontalAlignment,
            content = content,
        )
        VerticalScrollbar(adapter = rememberScrollbarAdapter(state))
    }
}

@Composable
private fun ScrollableWrapper(modifier: Modifier, content: @Composable () -> Unit) {
    Layout(
        content = content,
        modifier = modifier,
    ) { measurables, constraints ->
        val columnPlaceable = measurables[0].measure(constraints)
        val scrollbarPlaceable = measurables[1].measure(
            Constraints(
                minHeight = columnPlaceable.height,
                maxHeight = columnPlaceable.height,
                maxWidth = constraints.maxWidth,
            )
        )
        layout(columnPlaceable.width, columnPlaceable.height) {
            columnPlaceable.place(0, 0)
            scrollbarPlaceable.place(max(0, columnPlaceable.width - scrollbarPlaceable.width), 0)
        }
    }
}