PulseAnimation.kt

import android.animation.ObjectAnimator
import android.view.View

/**
 * Simple class used to pulse a view infinitely then fade in when stopped.
 * Created by tsloan on 11/15/2017.
 */
class PulseAnimation(view: View) {

    private var pulseAnimation : ObjectAnimator? = null

    private var view : View? = null

    init {
        this.view = view
    }

    /**
     * Starts the pulsing animation
     * @param initialAlpha Initial alpha value of the view (default: 100%)
     * @param endAlpha End alpha value of the view (default: 30%)
     * @param duration How long the pulse cycle is going to take (default: 400 ms)
     */
    fun startAnimation(initialAlpha : Float = 1.0f, endAlpha: Float = 0.3f, duration: Long = 400) {
        view?.let {
            pulseAnimation = ObjectAnimator.ofFloat(it, "alpha", initialAlpha, endAlpha)
            pulseAnimation?.duration = duration
            pulseAnimation?.repeatCount = ObjectAnimator.INFINITE
            pulseAnimation?.repeatMode = ObjectAnimator.REVERSE
            pulseAnimation?.start()
        }
    }

    /**
     * Stops the animation and fades-in the view for a smooth transition.
     * @param initialAlpha Initial alpha value of the view (default: 30%)
     * @param endAlpha End alpha value of the view (default: 100%)
     * @param duration How long the fade-in is going to take (default: 400 ms)
     */
    fun stopAnimation(initialAlpha : Float = 0.3f, endAlpha: Float = 1.0f, duration: Long = 400) {
        view?.let {
            pulseAnimation?.end()
            val fadeInAnim = ObjectAnimator.ofFloat(it, "alpha", initialAlpha, endAlpha)
            fadeInAnim.duration = duration
            fadeInAnim.start()
        }
    }
    
    /**
     * Releases UI components to prevent memory leaks
     */
    fun release() {
        pulseAnimation?.cancel()
        view = null
    }
}