AnimatableInsetsRulers

import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.safeDrawingPadding
import androidx.compose.foundation.layout.size
import androidx.compose.material.TextField
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.layout.InsetsRulers
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.MeasureResult
import androidx.compose.ui.layout.MeasureScope
import androidx.compose.ui.node.LayoutModifierNode
import androidx.compose.ui.node.ModifierNodeElement
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.fontscaling.MathUtils.lerp

class LandOnImeModifierNode : Modifier.Node(), LayoutModifierNode {
    override fun MeasureScope.measure(
        measurable: Measurable,
        constraints: Constraints
    ): MeasureResult {
        return if (constraints.hasBoundedWidth && constraints.hasBoundedHeight) {
            val width = constraints.maxWidth
            val height = constraints.maxHeight
            layout(width, height) {
                val node = this@LandOnImeModifierNode
                val placeable = measurable.measure(constraints)
                val bottom =
                    with(node) {
                        if (!InsetsRulers.Ime.isAnimating(node)) {
                            if (InsetsRulers.Ime.isVisible(node)) {
                                InsetsRulers.Ime.bottom.current(Float.NaN)
                            } else {
                                Float.NaN
                            }
                        } else {
                            val start = InsetsRulers.Ime.source.bottom.current(Float.NaN)
                            val end = InsetsRulers.Ime.target.bottom.current(Float.NaN)
                            val fraction = InsetsRulers.Ime.interpolatedFraction(node)
                            if (start.isNaN() || end.isNaN()) {
                                Float.NaN // don't know where it is animating
                            } else if (start > end) { // animate IME up
                                lerp(placeable.height.toFloat(), end, fraction)
                            } else { // animating down
                                lerp(start, placeable.height.toFloat(), fraction)
                            }
                        }
                    }
                val y =
                    if (bottom.isNaN()) {
                        0 // place at the top
                    } else if (bottom > height) {
                        height - placeable.height // place at the bottom
                    } else { // place somewhere in the middle
                        bottom.roundToInt() - placeable.height
                    }
                placeable.place(0, y)
            }
        } else {
            // Can't work with the rulers if we can't take the full size
            val placeable = measurable.measure(constraints)
            layout(placeable.width, placeable.height) { placeable.place(0, 0) }
        }
    }
}

class LandOnImeElement : ModifierNodeElement<LandOnImeModifierNode>() {
    override fun create(): LandOnImeModifierNode = LandOnImeModifierNode()

    override fun hashCode(): Int = 0

    override fun equals(other: Any?): Boolean = other is LandOnImeElement

    override fun update(node: LandOnImeModifierNode) {}
}

Box(Modifier.fillMaxSize()) {
    Box(LandOnImeElement()) {
        // This content will rest at the top, but then animate to land on the IME when it is
        // animated in.
        Box(Modifier.size(100.dp).background(Color.Blue))
    }
    TextField(
        "Hello World",
        onValueChange = {},
        Modifier.safeDrawingPadding().align(Alignment.BottomEnd)
    )
}