https://x.com/m4kvn/status/1731261839143833853?s=20

CompareViewer.kt

@Composable
fun CompareViewer() {
    val density = LocalDensity.current
    val separatorWidth: Dp = 1.dp
    val separatorWidthPx = with(density) { separatorWidth.toPx() }
    BoxWithConstraints(modifier = Modifier.fillMaxWidth()) {
        val parentWidthDp = maxWidth
        val parentWidthPx = with(density) { parentWidthDp.toPx() }
        val initialOffsetX = parentWidthPx / 2
        var offsetX by remember { mutableStateOf(initialOffsetX) }
        val boxWidthDp = with(density) { offsetX.toDp() }
        Box(
            modifier = Modifier
                .background(Color.White)
                .draggable(
                    orientation = Orientation.Horizontal,
                    state = rememberDraggableState(onDelta = { delta ->
                        offsetX = (offsetX + delta)
                            .coerceIn(0f, parentWidthPx - separatorWidthPx)
                    })
                )
        ) {
            Image(
                imageVector = Icons.Default.AccountBox,
                contentDescription = null,
                modifier = Modifier
                    .size(parentWidthDp)
            )
            Box(
                modifier = Modifier
                    .width(boxWidthDp)
                    .height(parentWidthDp)
                    .background(Color.White)
                    .clipToBounds()
                    .wrapContentWidth(Alignment.Start, unbounded = true)
            ) {
                Image(
                    imageVector = Icons.Default.AccountCircle,
                    contentDescription = null,
                    modifier = Modifier
                        .size(parentWidthDp)
                )
            }
            Box(
                modifier = Modifier
                    .offset { IntOffset(x = offsetX.roundToInt(), y = 0) }
                    .width(separatorWidth)
                    .height(parentWidthDp)
                    .background(Color.Black)
            )
        }
    }
}