UnderKeyboardViewElevator.kt

import android.annotation.SuppressLint
import android.graphics.Rect
import android.os.Build
import android.view.View
import android.view.ViewTreeObserver
import androidx.core.view.updatePaddingRelative

class UnderKeyboardViewElevator(private val decorView: View, private val contentView: View) {

    private var initialPaddingBottom: Int = contentView.paddingBottom

    private var onGlobalLayoutListener = ViewTreeObserver.OnGlobalLayoutListener {
        val r = Rect()
        decorView.getWindowVisibleDisplayFrame(r)
        
        val height = decorView.context.resources.displayMetrics.heightPixels
        val diff = height - r.bottom

        if (diff != 0) {
            val targetPadding = diff + initialPaddingBottom
            if (contentView.paddingBottom != targetPadding) {
                contentView.updatePaddingRelative(bottom = targetPadding)
            }
        } else {
            if (contentView.paddingBottom != initialPaddingBottom) {
                contentView.updatePaddingRelative(bottom = initialPaddingBottom)
            }
        }
    }

    init {
        //only required on newer android versions. it was working on API level 19
        if (Build.VERSION.SDK_INT >= 19) {
            decorView.viewTreeObserver.addOnGlobalLayoutListener(onGlobalLayoutListener)
        }
    }

    fun enable() {
        if (Build.VERSION.SDK_INT >= 19) {
            decorView.viewTreeObserver.addOnGlobalLayoutListener(onGlobalLayoutListener)
        }
    }

    fun disable() {
        if (Build.VERSION.SDK_INT >= 19) {
            decorView.viewTreeObserver.removeOnGlobalLayoutListener(onGlobalLayoutListener)
        }
    }
}