用画布画画

Question

如何使用画布绘制蓝色背景的透明颜色的选定字段？

在官方文档中，我发现像this的smth。但是仍然存在如何实施它的问题。

另外，例如，我试图画线：

private fun someFun(canvas: Canvas, parent: RecyclerView) {
    val radius: Float = parent.context.resources.getDimension(R.dimen.dimen_12)
    val paint = Paint()
    paint.color = ContextCompat.getColor(parent.context, R.color.primary)
    paint.style = Paint.Style.FILL

    val path = Path()
    path.moveTo(0f, 0f)
    path.lineTo(0f, radius)
    path.arcTo(RectF(0f, 0f, radius * 2, radius * 2), 270f, -90f)
    path.close()
    canvas.drawPath(path, paint)
}

并得到像这样的smth：

Answer 1

决定采用下一种方式：

 private fun drawRoundedCorners(canvas: Canvas, parent: RecyclerView) {
    val radius: Float = parent.context.resources.getDimension(R.dimen.dimen_12)
    val paint = Paint()
    paint.color = ContextCompat.getColor(parent.context, R.color.primary)
    paint.style = Paint.Style.FILL

    val path = Path()
    path.moveTo(0f, 0f)
    path.lineTo(150f, 0f)
    path.arcTo(RectF(0f, 0f, radius * 2, radius * 2), 270f, -90f)

    path.moveTo(parent.width.toFloat(), 0f)
    path.lineTo(parent.width.toFloat(), 0f)
    path.arcTo(RectF(parent.width.toFloat() - radius * 2, 0f, parent.width.toFloat(),
            radius * 2), 270f, 90f)
    path.close()
    canvas.drawPath(path, paint)
}