PrecomputedText.kt

fun setTextAsync(textView: TextView, longString: String) {
  val params = textView.textMetricsParams
  val ref = WeakReference(textView)

  CoroutineScope.launch(Dispatchers.Default) {
    val pText = PrecomputedText.create(longString, params)
    withContext(Dispatchers.Main) {
      ref.get()?.let { textView ->
        textView.text = pText
      }
    }
  }
}