Android 在卡片上创建圆角底部边框

你可以try 用drawBehind个修改器进行实验.堆叠圆形矩形也涉及，但它看起来更干净，我.

下面的代码片断会产生以下结果:

当您取消对带有半透明backgroundColor的线条的注释时，您可以看到卡片后面绘制的内容(它是全圆角矩形，因为您不能使用此方法在画布上单独设置角点):

@Preview
@Composable
fun CardWithThickness(modifier: Modifier = Modifier) {
    val cardHeightDp = 100.dp
    val cornerRadiusDp = 20.dp
    val borderThicknessDp = 2.dp
    Box(
        modifier = Modifier.padding(bottom = borderThicknessDp)
    ) {
        Card(
            // backgroundColor = Color(0x99999999),
            shape = RoundedCornerShape(size = cornerRadiusDp),
            modifier = Modifier
                .size(180.dp, cardHeightDp)
                .drawBehind {
                    drawRoundRect(
                        color = Color.Red,
                        topLeft = Offset(0f, (cardHeightDp - 2 * cornerRadiusDp).toPx()),
                        size = this.size.copy(height = (2 * cornerRadiusDp + borderThicknessDp).toPx()),
                        cornerRadius = CornerRadius(cornerRadiusDp.toPx())
                    )
                },
        ) {
            // ...
        }
    }
}