Jetpack Compose in ShaderBrush

ShaderBrush.kt

@Composable
fun Modifier.starBackgroundAnimated(): Modifier {
    val image = ImageBitmap.imageResource(R.drawable.bg_image)
    val transition = rememberInfiniteTransition(label = "")
    val offset by transition.animateFloat(
        initialValue = 0f,
        targetValue = image.width.toFloat(),
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 10000, easing = LinearEasing),
            repeatMode = RepeatMode.Reverse
        ), label = "offset"
    )

    return this.then(Modifier.drawWithCache {
        onDrawWithContent {
            val shader = ImageShader(image, TileMode.Mirror, TileMode.Mirror)
            val paint = Paint().apply {
                this.shader = shader
            }
            withTransform({
                translate(left = -offset)
            }) {
                drawRect(
                    brush = ShaderBrush(shader),
                    size = Size(size.width + offset, size.height)
                )
            }
            drawContent()
        }
    })
}

@Composable
fun Modifier.animatedGradientBackground(): Modifier {
    val transition = rememberInfiniteTransition()
    val color1 by transition.animateColor(
        initialValue = Color.White,
        targetValue = Color.Red,
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 5000, easing = LinearEasing),
            repeatMode = RepeatMode.Reverse
        ), label = ""
    )
    val color2 by transition.animateColor(
        initialValue = Color.White.copy(alpha = 0.6f),
        targetValue = Color.LightGray.copy(alpha = 0.6f),
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 5000, easing = LinearEasing),
            repeatMode = RepeatMode.Reverse
        ), label = ""
    )
    val color3 by transition.animateColor(
        initialValue = Color.White.copy(alpha = 0.4f),
        targetValue = Color.Red.copy(alpha = 0.4f),
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 5000, easing = LinearEasing),
            repeatMode = RepeatMode.Reverse
        ), label = ""
    )
    val color4 by transition.animateColor(
        initialValue = Color.Transparent,
        targetValue = Color.Magenta.copy(alpha = 0.4f),
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 5000, easing = LinearEasing),
            repeatMode = RepeatMode.Reverse
        ), label = ""
    )

    return this.background(
        Brush.verticalGradient(
            0f to color1,
            0.5f to color2,
            0.85f to color3,
            1f to color4
        )
    )
}

@Preview
@Composable
fun PreviewStarBackgroundAnimated() {
    Box(
        modifier = Modifier
            .size(1000.dp)
            .background(Color.White)
            .starBackgroundAnimated()
            .animatedGradientBackground()
    )
}