android - Jetpack compose 中的波浪盒

Question

有没有办法用 Canvas 制作一个带有波浪形顶部的盒子？

我想知道这个效果能不能直接用Canvas来实现，没必要有滚动动画。

标签： androidkotlinandroid-canvasandroid-jetpack-composeandroid-jetpack

Answer 1

目前还不太清楚你为什么在谈论Canvas. 要裁剪这样的视图，您可以使用自定义Shape并将其应用到您的视图中Modifier.clip。这是您可以使用的形状：

class WavyShape(
    private val period: Dp,
    private val amplitude: Dp,
) : Shape {
    override fun createOutline(
        size: Size,
        layoutDirection: LayoutDirection,
        density: Density,
    ) = Outline.Generic(Path().apply {
        val wavyPath = Path().apply {
            val halfPeriod = with(density) { period.toPx() } / 2
            val amplitude = with(density) { amplitude.toPx() }
            moveTo(x = -halfPeriod / 2, y = amplitude)
            repeat(ceil(size.width / halfPeriod + 1).toInt()) { i ->
                relativeQuadraticBezierTo(
                    dx1 = halfPeriod / 2,
                    dy1 = 2 * amplitude * (if (i % 2 == 0) 1 else -1),
                    dx2 = halfPeriod,
                    dy2 = 0f,
                )
            }
            lineTo(size.width, size.height)
            lineTo(0f, size.height)
        }
        val boundsPath = Path().apply {
            addRect(Rect(offset = Offset.Zero, size = size))
        }
        op(wavyPath, boundsPath, PathOperation.Intersect)
    })
}

如果Canvas出于某种原因确实需要在内部使用它，可以将Path我在内部创建的相同传递WavyShape给DrawScope.clipPath，这样clipPath块的内容就会被剪切。

将自定义形状应用于您的Image或任何其他视图：

Image(
    painter = painterResource(id = R.drawable.my_image_1),
    contentDescription = null,
    contentScale = ContentScale.FillBounds,
    modifier = Modifier
        .clip(WavyShape(period = 100.dp, amplitude = 50.dp))
)

结果：