Compose transparency and blend issues with RNG

[yschimke]

@Composable
@WearPreviewLargeRound
internal fun TestCaseBox() {
    Box(
        modifier = Modifier
            .fillMaxSize()
            .background(Brush.horizontalGradient(listOf(Color.Blue, Color.Green, Color.Blue)))
    ) {
        Box(modifier = Modifier
            .fillMaxSize(0.8f)
            .align(Alignment.Center)
            .graphicsLayer(compositingStrategy = CompositingStrategy.Offscreen)
            .drawWithContent {
                drawContent()
                drawRect(
                    brush = Brush.verticalGradient(
                        listOf(
                            Color.Black,
                            Color.Transparent,
                            Color.Black
                        )
                    ),
                    blendMode = BlendMode.DstIn
                )
            }) {
            Box(
                modifier = Modifier
                    .fillMaxSize()
                    .background(Color.Red)
            )
        }
    }
}

With Compose Previews

With RNG Screenshots

Ignore the device clipping

[yschimke]

Sample PR

https://github.com/google/horologist/pull/2173/files