Some simple Kotlin view extensions

ViewExt.kt

import android.view.View
import android.view.View.GONE
import android.view.View.INVISIBLE
import android.view.View.VISIBLE
import android.view.ViewTreeObserver
import android.widget.AdapterView
import android.widget.Spinner

fun View.show() {
  visibility = VISIBLE
}

fun View.conceal() {
  visibility = INVISIBLE
}

fun View.hide() {
  visibility = GONE
}

fun View.enable() {
  isEnabled = true
}

fun View.disable() {
  isEnabled = false
}

fun View.showOrHide(show: Boolean) = if (show) show() else hide()

fun View.onLayout(cb: () -> Unit) {
  if (this.viewTreeObserver.isAlive) {
    this.viewTreeObserver.addOnGlobalLayoutListener(
        object : ViewTreeObserver.OnGlobalLayoutListener {
          override fun onGlobalLayout() {
            cb()
            [email protected](this)
          }
        })
  }
}

// Spinners

fun Spinner.onItemSelected(cb: (index: Int) -> Unit) {
  onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
    override fun onNothingSelected(parent: AdapterView<*>?) = Unit

    override fun onItemSelected(
      parent: AdapterView<*>?,
      view: View?,
      position: Int,
      id: Long
    ) = cb(position)
  }
}

// ScrollView

fun ScrollView.onScroll(cb: (y: Int) -> Unit) =
  viewTreeObserver.addOnScrollChangedListener { cb(scrollY) }

// EditText

fun EditText.onTextChanged(
  @IntRange(from = 0, to = 10000) debounce: Int = 0,
  cb: (text: String) -> Unit
) {
  addTextChangedListener(object : TextWatcher {
    val callbackRunner = Runnable {
      cb(text.trim().toString())
    }

    override fun afterTextChanged(s: Editable?) = Unit

    override fun beforeTextChanged(
      s: CharSequence,
      start: Int,
      count: Int,
      after: Int
    ) = Unit

    override fun onTextChanged(
      s: CharSequence,
      start: Int,
      before: Int,
      count: Int
    ) {
      removeCallbacks(callbackRunner)
      if (debounce == 0) {
        callbackRunner.run()
      } else {
        postDelayed(callbackRunner, debounce.toLong())
      }
    }
  })
}