A placeholder with animation for android compose

placeholder.kt

fun Modifier.gradientProcessingBackground() : Modifier = composed {
    val infiniteYTransition = rememberInfiniteTransition()
    val state = infiniteYTransition.animateFloat(
        initialValue = 0f,
        targetValue = 0.7f,
        animationSpec = infiniteRepeatable(
            animation = tween(500, easing = EaseInOutExpo),
            repeatMode = RepeatMode.Restart
        )
    )
    val animationY by state

    val mainColor =
        MaterialTheme.colors.secondary.overlay(MaterialTheme.colors.background, 0.7f)
    val backColor = MaterialTheme.colors.background
    val gradient = remember(animationY) {
        Statics.gradiantBrush(y = animationY, mainColor, backColor)
    }
    clip(RoundedCornerShape(4.dp))
        .background(gradient)
}
fun gradiantBrush(y: Float, mainColor: Color, backColor: Color): Brush {
    val yC = (y * 0.7f) + 0.3f
    return Brush.linearGradient(
        0f to backColor,
        yC - 0.3f to mainColor,
        yC to mainColor,
        1f to backColor
    )
}