Useful Kotlin Extension Function

Here is the collection of useful Kotlin Extension function that might speed your development. Just Make Extension.Kt Kotlin file copy and paste this code.

fun ImageView.loadImageFromUrl(url: String) {
  Glide.with(context)
      .load(url)
      .into(this)
}

fun Activity.hideKeyboard() {
  val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
  imm.hideSoftInputFromWindow(window.decorView.windowToken, 0)
}

/**
 * Extension method to remove the required boilerplate for running code after a view has been
 * inflated and measured.
 *
 * @author Antonio Leiva
 * @see <a href="https://antonioleiva.com/kotlin-ongloballayoutlistener/>Kotlin recipes: OnGlobalLayoutListener</a>
 */
inline fun <T : View> T.afterMeasured(crossinline f: T.() -> Unit) {
  viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
    override fun onGlobalLayout() {
      if (measuredWidth > 0 && measuredHeight > 0) {
        viewTreeObserver.removeOnGlobalLayoutListener(this)
        f()
      }
    }
  })
}

/**
 * Extension method to simplify the code needed to apply spans on a specific sub string.
 */
inline fun SpannableStringBuilder.withSpan(vararg spans: Any, action: SpannableStringBuilder.() -> Unit):
    SpannableStringBuilder {
  val from = length
  action()

  for (span in spans) {
    setSpan(span, from, length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
  }

  return this
}

/**
 * Extension method to provide simpler access to {@link ContextCompat#getColor(int)}.
 */
fun Context.getColorCompat(color: Int) = ContextCompat.getColor(this, color)

/**
 *  Extension method to provide simpler access to {@link ContextCompat#getColor(int)}
 *  from a [Fragment].
 */
fun Fragment.getColorCompat(color: Int) = context?.getColorCompat(color)

/**
 * Extension method to provide simpler access to {@link ContextCompat#getDrawableCompat(int)}.
 */
fun Context.getDrawableCompat(drawableResId: Int): Drawable? = ContextCompat
    .getDrawable(this, drawableResId)

/**
 * Extension method to provide simpler access to {@link ContextCompat#getDrawableCompat(int)}
 * from a [Fragment].
 */
fun Fragment.getDrawableCompat(drawableResId: Int) = context?.getDrawableCompat(drawableResId)!!

/**
 * Extension method to provide simpler access to {@link View#getResources()#getString(int)}.
 */
fun View.getString(stringResId: Int): String = resources.getString(stringResId)

/**
 * Extension method to provide show keyboard for View.
 */
fun View.showKeyboard() {
  val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
  this.requestFocus()
  imm.showSoftInput(this, 0)
}

/**
 * Extension method to provide hide keyboard for [Activity].
 */
fun Activity.hideSoftKeyboard() {
  if (currentFocus != null) {
    val inputMethodManager = getSystemService(Context
        .INPUT_METHOD_SERVICE) as InputMethodManager
    inputMethodManager.hideSoftInputFromWindow(currentFocus!!.windowToken, 0)
  }
}

/**
 * Extension method to provide hide keyboard for [Fragment].
 */
fun Fragment.hideSoftKeyboard() {
  activity?.hideSoftKeyboard()
}

/**
 * Extension method to provide hide keyboard for [View].
 */
fun View.hideKeyboard() {
  val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
  imm.hideSoftInputFromWindow(windowToken, 0)
}

/**
 * Extension method to int time to 2 digit String
 */
fun Int.twoDigitTime() = if (this < 10) "0" + toString() else toString()

/**
 * Extension method to provide quicker access to the [LayoutInflater] from [Context].
 */
fun Context.getLayoutInflater() = getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater

/**
 * Extension method to provide quicker access to the [LayoutInflater] from a [View].
 */
fun View.getLayoutInflater() = context.getLayoutInflater()

/**
 * Extension method to replace all text inside an [Editable] with the specified [newValue].
 */
fun Editable.replaceAll(newValue: String) {
  replace(0, length, newValue)
}

/**
 * Extension method to replace all text inside an [Editable] with the specified [newValue] while
 * ignoring any [android.text.InputFilter] set on the [Editable].
 */
fun Editable.replaceAllIgnoreFilters(newValue: String) {
  val currentFilters = filters
  filters = emptyArray()
  replaceAll(newValue)
  filters = currentFilters
}

/**
 * Extension method to cast a char with a decimal value to an [Int].
 */
fun Char.decimalValue(): Int {
  if (!isDigit())
    throw IllegalArgumentException("Out of range")
  return this.toInt() - '0'.toInt()
}

/**
 * Extension method to simplify view binding.
 */
fun <T : ViewDataBinding> View.bind() = DataBindingUtil.bind<T>(this) as T

/**
 * Extension method to simplify view inflating and binding inside a [ViewGroup].
 *
 * e.g.
 * This:
 *<code>
 *     binding = bind(R.layout.widget_card)
 *</code>
 *
 * Will replace this:
 *<code>
 *     binding = DataBindingUtil.inflate(getLayoutInflater(), R.layout.widget_card, this, true)
 *</code>
 */
fun <T : ViewDataBinding> ViewGroup.bind(layoutId: Int): T {
  return DataBindingUtil.inflate(getLayoutInflater(), layoutId, this, true)
}

fun <T : ViewDataBinding> Activity.bind(layoutId: Int): T {
  return DataBindingUtil.setContentView(this, layoutId)
}

fun String.dateInFormat(format: String): Date? {
  val dateFormat = SimpleDateFormat(format, Locale.US)
  var parsedDate: Date? = null
  try {
    parsedDate = dateFormat.parse(this)
  } catch (ignored: ParseException) {
    ignored.printStackTrace()
  }
  return parsedDate
}

fun getClickableSpan(color: Int, action: (view: View) -> Unit): ClickableSpan {

  return object : ClickableSpan() {
    override fun onClick(view: View) {
      action(view)
    }

    override fun updateDrawState(ds: TextPaint) {
      super.updateDrawState(ds)
      ds.color = color
    }
  }
}

/**
 * Extension method to be used as the body for functions that are not yet implemented, which will
 * display a [Toast] with the specified [message].
 */
fun Fragment.NOT_IMPL(message: String = "This action is not implemented yet!") {
  TOAST(message)
}

/**
 * Extension method used to display a [Toast] message to the user.
 */
fun Fragment.TOAST(message: String, duration: Int = Toast.LENGTH_SHORT) {
  Toast.makeText(context, message, duration).show()
}

/**
 * Extension method used to display a [Toast] message to the user.
 */
fun Fragment.TOAST(messageResId: Int, duration: Int = Toast.LENGTH_SHORT) {
  Toast.makeText(context, messageResId, duration).show()
}

/**
 * Extension method use to display a [Snackbar] message to the user.
 */
fun View.displaySnakbar(message: String, duration: Int = Snackbar.LENGTH_SHORT): Snackbar {
  val snakbar = Snackbar.make(this, message, duration)
  snakbar.show()
  return snakbar
}

/**
 * Extension method use to display a [Snackbar] message to the user.
 */
fun View.displaySnakbar(messageResId: Int, duration: Int = Snackbar.LENGTH_SHORT): Snackbar {
  val snakbar = Snackbar.make(this, messageResId, duration)
  snakbar.show()
  return snakbar
}

/**
 * Extension method to return the view location on screen as a [Point].
 */
fun View.locationOnScreen(): Point {
  val location = IntArray(2)
  getLocationOnScreen(location)
  return Point(location[0], location[1])
}

/**
 * Extension method to return the view location in window as a [Point].
 */
fun View.locationInWindow(): Point {
  val location = IntArray(2)
  getLocationInWindow(location)
  return Point(location[0], location[1])
}

/**
 * Extension method used to return the value of the specified float raised to the power
 * of the specified [exponent].
 */
fun Float.pow(exponent: Float) = Math.pow(this.toDouble(), exponent.toDouble()).toFloat()

/**
 * Extension method to provide show keyboard for View.
 */
fun View.gone() {
  if (visibility != View.GONE) {
    visibility = View.GONE
  }
}

/**
 * Extension method to provide show keyboard for View.
 */
fun View.visible() {
  if (visibility != View.VISIBLE) {
    visibility = View.VISIBLE
  }
}

/**
 * Convert a [Boolean] value to a view visibility [Int].
 */
fun Boolean.toViewVisibility(valueForFalse: Int = View.GONE): Int {
  return if (this) {
    View.VISIBLE
  } else {
    valueForFalse
  }
}

/**
 * Method used to easily retrieve [WindowManager] from [Context].
 */
fun Context.getWindowManager() = getSystemService(Context.WINDOW_SERVICE) as WindowManager

/**
 * Method used to easily retrieve display size from [Context].
 */
fun Context.getDisplaySize() = Point().apply {
  getWindowManager().defaultDisplay.getSize(this)
}

/**
 * Method used to easily retrieve display size from [View].
 */
fun View.getDisplaySize() = context.getDisplaySize()

/**
 * Provide the ability to snap to a specified [position] in the specified [recyclerView]
 * using [SnapHelper].
 */
fun SnapHelper.snapToPosition(recyclerView: RecyclerView, position: Int) {
  recyclerView.apply {
    val view = findViewHolderForAdapterPosition(position)?.itemView
    val snapPositions = view?.let {
      layoutManager?.let { it1 -> calculateDistanceToFinalSnap(it1, it) }
    }

    snapPositions?.let { smoothScrollBy(it[0], it[1]) }
  }
}

/**
 * Return whether Keyboard is currently visible on screen or not.
 *
 * @return true if keyboard is visible.
 */
fun Activity.isKeyboardVisible(): Boolean {
  val r = Rect()

  //r will be populated with the coordinates of your view that area still visible.
  window.decorView.getWindowVisibleDisplayFrame(r)

  //get screen height and calculate the difference with the usable area from the r
  val height = getDisplaySize().y
  val diff = height - r.bottom

  // If the difference is not 0 we assume that the keyboard is currently visible.
  return diff != 0
}

/**
 * Provides simpler access to the [ViewTreeObserver] inside a fragment.
 *
 * @return the [ViewTreeObserver] of the [Activity] this fragment currently attached to, or null
 * if the fragment is detached.
 */
fun Fragment.getViewTreeObserver() = activity?.window?.decorView?.viewTreeObserver

/**
 * Extension method to set width for View.
 */
fun View.setWidth(value: Int) {
  val lp = layoutParams
  lp?.let {
    lp.width = value
    layoutParams = lp
  }
}

/**
 * Extension method to display Width for Context.
 */
fun Context.displayWidth(): Int = getDisplaySize().x

/**
 * Retrieve a decoded bitmap from resources, or null if the image could not be decoded.
 */
fun Context.decodeBitmap(resId: Int): Bitmap? = BitmapFactory.decodeResource(resources, resId)