viewToBitmap.kt

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    override fun onResume() {
        super.onResume()

        val customView = CustomView(applicationContext)
        customView.measure(View.MeasureSpec.makeMeasureSpec(1280, View.MeasureSpec.EXACTLY),
                View.MeasureSpec.makeMeasureSpec(720, View.MeasureSpec.EXACTLY))
        customView.layout(0, 0, customView.measuredWidth, customView.measuredHeight)

        loadBitmapFromView(customView).let { bitmap ->
            this.imageView.setImageBitmap(bitmap)
        }
    }

    fun loadBitmapFromView(view: View): Bitmap? {
        val bitmap: Bitmap = Bitmap.createBitmap(view.width, view.height, Bitmap.Config.ARGB_8888)
        val canvas = Canvas(bitmap)
        view.layout(view.left, view.top, view.right, view.bottom)
        view.draw(canvas)
        return bitmap
    }
}