Reveal animations for views (Android)

Animations.kt

import android.animation.Animator
import android.animation.AnimatorListenerAdapter
import android.annotation.TargetApi
import android.os.Build
import android.view.View
import android.view.ViewAnimationUtils


/**
 * Animation.
 */


/**
 * Simple reveal, expands from screen center
 * */
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
fun View.enterReveal() {

    val cx = measuredWidth / 2
    val cy = measuredHeight / 2

    val finalRadius = Math.max(width, height) / 2
    val anim = ViewAnimationUtils.createCircularReveal(this, cx, cy, 0f, finalRadius.toFloat())

    visibility = View.VISIBLE
    anim.start()
}

/**
 * Expands from divider, for example, from width and height / 4 to screen
 * Divider must be > 0
 * */
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
fun View.enterReveal(divider: Int, callback: () -> Any) {

    if (divider <= 0) {
        throw IllegalArgumentException("Didiver must be > 0")
    }

    val cx = measuredWidth / divider
    val cy = measuredHeight / divider

    val finalRadius = Math.max(width, height) / divider

    val anim = ViewAnimationUtils.createCircularReveal(this, cx, cy, 0f, finalRadius.toFloat())

    anim.addListener(object : AnimatorListenerAdapter() {
        override fun onAnimationEnd(animation: Animator) {
            super.onAnimationEnd(animation)
            callback.invoke()
        }
    })

    visibility = View.VISIBLE
    anim.start()
}

/**
 * Expands from the center of "startRevealView"
 * Divider must be > 0
 * */
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
fun View.enterReveal(startRevealView: View, divider: Int, callback: () -> Any) {
    if (divider <= 0) {
        throw IllegalArgumentException("Didiver must be > 0")
    }

    val location = IntArray(2)
    startRevealView.getLocationInWindow(location)
    val cx = location[0] + startRevealView.measuredWidth / 2
    val cy = location[1] + startRevealView.measuredHeight / 2

    val finalRadius = Math.max(width, height) / divider

    val anim = ViewAnimationUtils.createCircularReveal(this, cx, cy, 0f, finalRadius.toFloat())

    anim.addListener(object : AnimatorListenerAdapter() {
        override fun onAnimationEnd(animation: Animator) {
            super.onAnimationEnd(animation)
            callback.invoke()
        }
    })

    visibility = View.VISIBLE
    anim.start()
}

/***
 * From the window (divider = 1) or the divider to the center of the reveal view
 * Divider must be > 0
 */

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
fun View.exitReveal(endRevealView: View, divider: Int) {

    if (divider <= 0) {
        throw IllegalArgumentException("Didiver must be > 0")
    }

    val location = IntArray(2)
    endRevealView.getLocationInWindow(location)
    val cx = location[0] + endRevealView.measuredWidth / 2
    val cy = location[1] + endRevealView.measuredHeight / 2

    val initialRadius = Math.max(width, height) / divider

    val anim = ViewAnimationUtils.createCircularReveal(this, cx, cy, initialRadius.toFloat(), 0f)

    anim.addListener(object : AnimatorListenerAdapter() {
        override fun onAnimationEnd(animation: Animator) {
            super.onAnimationEnd(animation)
            visibility = View.INVISIBLE
        }
    })

    anim.start()
}

/**
 * From the window to the center
 * */

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
fun View.exitReveal() {
    // previously visible view

    // get the center for the clipping circle
    val cx = measuredWidth / 2
    val cy = measuredHeight / 2

    // get the initial radius for the clipping circle
    val initialRadius = width / 2

    // create the animation (the final radius is zero)
    val anim = ViewAnimationUtils.createCircularReveal(this, cx, cy, initialRadius.toFloat(), 0f)

    // make the view invisible when the animation is done
    anim.addListener(object : AnimatorListenerAdapter() {
        override fun onAnimationEnd(animation: Animator) {
            super.onAnimationEnd(animation)
            visibility = View.INVISIBLE
        }
    })

    // start the animation
    anim.start()
}