先看效果#

代码实现：

val colors = intArrayOf(
            Color.parseColor("#D3BEFF"),
            Color.parseColor("#9BABFD"),
            Color.parseColor("#5C97FB")
        )
val drawable = GradientDrawable()
drawable.gradientType = GradientDrawable.RECTANGLE
drawable.cornerRadius = 10f
drawable.orientation = GradientDrawable.Orientation.LEFT_RIGHT
drawable.colors = waterColors
topView.background = drawable

GradientDrawable想要其它设置可以自行查找api进行设置