Blink animation Kotlin

Question

I have been struggling on this for a few days. I implemented a blink animation code for TextView. However, I think I need to fix little bit of fromAlpha toAlpha. It seems gradually fade in and fade out if you just put fromAplha = 0.0f and toAplha = 1.0f. How can I make it without fade like flicker? Please help me.

private fun View.blink(
    times: Int = Animation.INFINITE,
    duration: Long = 800L,
    offset: Long = 20L,
    minAlpha: Float = 0.0f,
    maxAlpha: Float = 1.0f,
    repeatMode: Int = Animation.ABSOLUTE,
) {
    startAnimation(
        AlphaAnimation(minAlpha, maxAlpha).also {
            it.duration = duration
            it.startOffset = offset
            it.repeatMode = repeatMode
            it.repeatCount = times
        },
    )
}

Answer 1

You can create a custom interpolator for the animation that uses a step function.

object StepInterpolator: BaseInterpolator() {
    override fun getInterpolation(input: Float) =
       round(input)
}

private fun View.blink(
    times: Int = Animation.INFINITE,
    duration: Long = 800L,
    offset: Long = 20L,
    minAlpha: Float = 0.0f,
    maxAlpha: Float = 1.0f,
    repeatMode: Int = Animation.ABSOLUTE,
) {
    startAnimation(
        AlphaAnimation(minAlpha, maxAlpha).apply {
            duration = duration
            startOffset = offset
            repeatMode = repeatMode
            repeatCount = times
            interpolator = StepInterpolator
        },
    )
}