view 화면을 file로 저장하기

private fun saveView(view: View, context: Context, num: Int) : File? {
    val Path = Environment.getExternalStorageDirectory().absolutePath
    val dirPath = "${Path}/allokal/signature"
    var file : File? = null
    val b = Bitmap.createBitmap(
        view.width, view.height, Bitmap.Config.RGB_565
    )

    val writePermission = ActivityCompat.checkSelfPermission(
        context,
        Manifest.permission.WRITE_EXTERNAL_STORAGE
    )
    if (writePermission == PackageManager.PERMISSION_GRANTED) {
        if (b != null) {
            try {
                val f = File("$dirPath/allokal")
                f.mkdir()
                val f2 = File("$dirPath/allokal/$num.png")
                val c = Canvas(b)
                view.draw(c)
                val fos = FileOutputStream(f2)
                b.compress(Bitmap.CompressFormat.PNG, 100, fos)
                fos.close()
                file = f2
            } catch (e: Exception) {
                Log.e("testSaveView", "Exception: $e")
            }
        }
        return file
    }else{
        return file
    }

}