Gradient color view for HSL color picker

QuadGradientView.kt

class QuadGradientView : FrameLayout {
    private var currentHue = 0f

    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
        setWillNotDraw(false)
    }

    constructor(context: Context) : super(context) {
        setWillNotDraw(false)
    }

    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(
        context,
        attrs,
        defStyleAttr
    ) {
        setWillNotDraw(false)
    }

    private val paint: Paint by lazy {
        Paint(Paint.ANTI_ALIAS_FLAG).apply {
            style = Paint.Style.FILL
            shader = ComposeShader(
                LinearGradient(
                    0f,
                    0f,
                    width.toFloat(),
                    0f,
                    Color.argb(255, 255, 255, 255),
                    Color.argb(0, 255, 255, 255),
                    Shader.TileMode.CLAMP
                ),
                LinearGradient(
                    0f,
                    height.toFloat(),
                    0f,
                    0f,
                    Color.argb(255, 0, 0, 0),
                    Color.argb(0, 0, 0, 0),
                    Shader.TileMode.CLAMP
                ),
                PorterDuff.Mode.SRC_OVER
            )
        }
    }

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        canvas.drawColor(Color.HSVToColor(floatArrayOf(currentHue, 1f, 1f)))
        canvas.drawPaint(paint)
    }
}

Example