ViewOnLayout.kt

import android.view.View
import android.view.ViewTreeObserver

fun View.onLayout(cb: () -> Unit) {
  if (this.viewTreeObserver.isAlive) {
    this.viewTreeObserver.addOnGlobalLayoutListener(
        object : ViewTreeObserver.OnGlobalLayoutListener {
          override fun onGlobalLayout() {
            cb()
            this@onLayout.viewTreeObserver.removeOnGlobalLayoutListener(this)
          }
        })
  }
}