Some useful extension functions for Android development

_ Android extension functions

_

OnClickSpan.kt

import android.text.SpannableString
import android.text.Spanned
import android.text.method.LinkMovementMethod
import android.text.style.ClickableSpan
import android.view.View
import android.widget.TextView

/* Adds a [clickHandler] to the text starting at index [start] and ending at index [end] */
fun TextView.onClickSpan(start: Int, end: Int, clickHandler: () -> Unit) {
    movementMethod = LinkMovementMethod.getInstance()
    linksClickable = true

    val span = object : ClickableSpan() {
        override fun onClick(widget: View?) {
            clickHandler()
        }
    }

    val spannable = SpannableString(text)

    spannable.setSpan(span, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)

    text = spannable
}

Views.kt

import android.animation.Animator
import android.animation.AnimatorListenerAdapter
import android.view.View

fun View.show() {
    this.visibility = View.VISIBLE
}

fun View.hide() {
    this.visibility = View.GONE
}

fun View.isVisible() = this.visibility == View.VISIBLE

fun View.enable() {
    isEnabled = true
}

fun View.disable() {
    isEnabled = false
}

/* Fades the View out in [durationMs] time */
fun <T : View> T.animateOut(durationMs: Long = 250, onComplete: T.() -> Unit = {}) {
    animate().setDuration(durationMs)
            .alpha(0f)
            .setListener(object : AnimatorListenerAdapter() {
                override fun onAnimationEnd(animation: Animator?) {
                    hide()
                    alpha = 1f
                    onComplete()
                }
            })
}

/* Fades the View in in [durationMs] time */
fun <T : View> T.animateIn(durationMs: Long = 250, onComplete: T.() -> Unit = {}) {
    alpha = 0f
    show()
    animate().setDuration(durationMs)
            .alpha(1f)
            .setListener(object : AnimatorListenerAdapter() {
                override fun onAnimationEnd(animation: Animator?) {
                    onComplete()
                }
            })
}