Discovering RadialGradient

ShadowExample.kt

// With the assumption, this code is written inside a view
// choose a reasonable range of colors, some ranges won't be drawn and I don't know why actually.
private val shadowStartColor = 0x99ffffff.toInt()
private val shadowEndColor = 0x03ffffff
private val shadowSize = 50f
val radialGradientPaint =RadialGradient(centerX
, centerY,
radius,
intArrayOf(shadowStartColor, shadowEndColor),
floatArrayOf(0f,  1f),
Shader.TileMode.CLAMP).apply {
            isAntiAlias = true
            strokeJoin = Paint.Join.ROUND
            style = Paint.Style.FILL
            val mn = min(width, height)
            shader = RadialGradient(width / 2f, height / 2f, mn.toFloat(), intArrayOf(shadowStartColor, shadowEndColor), floatArrayOf(0f,  1f), Shader.TileMode.CLAMP)
            isDither = true
}

override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        canvas.drawOval(RectF(0f, 0f, width, height), radialGradientPaint)
}