Compose rounded Button with transparent background

Question

I am trying to display a Button with rounded corners and a 50% transparent background. My current attempt looks like this:

MaterialTheme {
    Surface(
        modifier = Modifier.fillMaxSize(),
        color = Color.Yellow
    ) {
        Column(modifier = Modifier.padding(10.dp)) {
            Button(
                modifier = Modifier
                    .clip(CircleShape),
                onClick = { },
                colors = ButtonDefaults.buttonColors(backgroundColor = Color.White.copy(alpha = 0.5f))
            ) {
                Text(
                    text = "My Button",
                    textAlign = TextAlign.Center
                )
            }
        }
    }
}

The result is not very pretty:

It looks like the issue is with with the shading, but I'm not sure how to remove it and just show the same color within the whole shape.

Answer 1

Turns out the shadow will disappear when the elevation is removed.

Button(
    modifier = Modifier
        .clip(CircleShape),
    onClick = { },
    elevation = null,
    colors = ButtonDefaults.buttonColors(backgroundColor = Color.White.copy(alpha = 0.5f))
) { ... }

Answer 2

Button is just a Surface wrapping the content that you provide. You could check the source. So, I just tweaked it a little

@Composable
fun HollowButton(
    onClick: () -> Unit,
    modifier: Modifier = Modifier,
    enabled: Boolean = true,
    interactionSource: MutableInteractionSource = remember { MutableInteractionSource() },
    elevation: ButtonElevation? = ButtonDefaults.elevation(),
    shape: Shape = MaterialTheme.shapes.small,
    border: BorderStroke? = null,
    colors: ButtonColors = ButtonDefaults.buttonColors(),
    contentPadding: PaddingValues = ButtonDefaults.ContentPadding,
    content: @Composable RowScope.() -> Unit
) {
    val contentColor by colors.contentColor(enabled)
    Surface(
        modifier = modifier,
        shape = shape,
        color = colors.backgroundColor(enabled).value.copy(0.5f), //Basically I refactored the alpha modification to here
        contentColor = contentColor.copy(alpha = 1f),
        border = border,
        elevation = elevation?.elevation(enabled, interactionSource)?.value ?: 0.dp,
        onClick = onClick,
        enabled = enabled,
        role = Role.Button,
        interactionSource = interactionSource,
        indication = rememberRipple()
    ) {
        CompositionLocalProvider(LocalContentAlpha provides contentColor.alpha) {
            ProvideTextStyle(
                value = MaterialTheme.typography.button
            ) {
                Row(
                    Modifier
                        .defaultMinSize(
                            minWidth = ButtonDefaults.MinWidth,
                            minHeight = ButtonDefaults.MinHeight
                        )
                        .padding(contentPadding),
                    horizontalArrangement = Arrangement.Center,
                    verticalAlignment = Alignment.CenterVertically,
                    content = content
                )
            }
        }
    }
}

Works like a charm.