Build Coupon UI - Start point (https://medium.com/@akexorcist/how-we-built-developer-friendly-coupon-ui-in-android-part-2-78933730d335)

CouponLayout.kt

val canvas: Canvas = /* ... */
val areaWidth = canvas.width
val areaHeight = canvas.height
val borderWidth = 2
val cornerRadius = 10
val semiCircleRadius = 20

val path = Path().apply {
    /* ... */
    moveTo(
        x = areaWidth - (cornerRadius + (borderWidth / 2f)), 
        y = borderWidth / 2f
    )
    /* ... */
}