Skip’s open-source SkipUI library implements the SwiftUI API for Android. To do so, SkipUI leverages Compose, Android’s own modern, declarative UI framework.

The parallels between SwiftUI and Compose are striking, especially when it comes to layout. SwiftUI uses HStack, VStack, and ZStack for basic layout, with modifiers like offset and padding to shift or pad the resulting placement. Compose uses Row, Column, and Box for basic layout, and it too has offset and padding modifiers. Compose has one odd omission, however: it doesn’t support negative padding! Supplying a negative value will throw an IllegalArgumentException.

SkipUI must support whatever SwiftUI supports, so internally we’ve replaced the standard Compose padding modifier with our own custom layout that works for both positive and negative values. We present that layout below, in case you find it useful in your own Compose work.


  1. SkipUI’s implementation is tied to SwiftUI internals, so this is an untested and simplified port of the actual code.
  2. Important: If you plan to use this in pure Compose code, expose it as a custom modifier for a more fluent API.
@Composable fun PaddingLayout(modifier: Modifier, top: Dp = 0.dp, leading: Dp = 0.dp, bottom: Dp = 0.dp, trailing: Dp = 0.dp, content: @Composable () -> Unit) {
    val density = LocalDensity.current
    val topPx = with(density) { top.roundToPx() }
    val bottomPx = with(density) { bottom.roundToPx() }
    val leadingPx = with(density) { leading.roundToPx() }
    val trailingPx = with(density) { trailing.roundToPx() }

    Layout(modifier = modifier, content = {
        // Compose content
    }) { measurables, constraints ->
        if (measurables.isEmpty()) {
            return layout(width: 0, height: 0) {}
        // Subtract the padding from the available size the content can use
        val updatedConstraints = constraints.copy(
            minWidth = constraint(constraints.minWidth, subtracting = leadingPx + trailingPx), 
            minHeight = constraint(constraints.minHeight, subtracting = topPx + bottomPx),
            maxWidth = constraint(constraints.maxWidth, subtracting = leadingPx + trailingPx),
            maxHeight = constraint(constraints.maxHeight, subtracting = topPx + bottomPx)
        val contentPlaceables = { it.measure(updatedConstraints) }
        // Layout within the padded size
        layout(width = contentPlaceables[0].width + leadingPx + trailingPx, height = contentPlaceables[0].height + topPx + bottomPx) {
            // Offset the content position by the leading and top padding
            for (contentPlaceable in contentPlaceables) {
                contentPlaceable.placeRelative(x = leadingPx, y = topPx)

// Subtract the given amount from a size constraint value, honoring Int.MAX_VALUE and preventing illegal negative constraints.
private fun constraint(value: Int, subtracting: Int): Int {
    if (value == Int.MAX_VALUE) {
        return value
    return max(0, value - subtracting)

We hope that you find this useful! If you have questions or suggestions for improvements, please reach out to us on Mastodon, via chat, or in our discussion forums.