Always keep text view in center of Constraint Layout

i want to create a custom view extending ConstraintLayout in which i am having a textview.I want text view to be always in center of ConstraintLayout irrespect of its width .Here is the code

class CustomView @JvmOverloads constructor(context: Context,attributeSet: AttributeSet):ConstraintLayout(context,attributeSet) {
var textView:AppCompatTextView
 var constraintView:ConstraintLayout


init {
    val height: String =
        attributeSet.getAttributeValue("http://schemas.android.com/apk/res/android", "layout_height")
    val width: String =
        attributeSet.getAttributeValue("http://schemas.android.com/apk/res/android", "layout_width")

    background=resources.getDrawable(R.drawable.upsell_unselected_text_bg_for_discount_rectangle)
    textView= AppCompatTextView(context)
    constraintView=this
    textView.id=R.id.vtextview
    constraintView.id=R.id.vlinecview
   textView.setTextColor(resources.getColor(R.color.black))

    textView.text="B"
    textView.rotation=90F
    textView.textSize=60F
    textView.setSingleLine()
    textView.maxLines=1
    textView.maxEms=7
    textView.ellipsize= TextUtils.TruncateAt.END
    textView.setHorizontallyScrolling(false)
    TextViewCompat.setAutoSizeTextTypeUniformWithConfiguration(textView, 30, 180, 1,TypedValue.COMPLEX_UNIT_SP);
    constraintView.addView(textView)
    var layoutParams=ConstraintLayout.LayoutParams(ConstraintSet.MATCH_CONSTRAINT_SPREAD,ConstraintSet.WRAP_CONTENT)
    layoutParams.topToTop=R.id.vlinecview
    layoutParams.bottomToBottom=R.id.vlinecview
    layoutParams.startToStart=R.id.vlinecview
    layoutParams.endToEnd=R.id.vlinecview
    textView.layoutParams=layoutParams
    textView.bringToFront()

    }

fun setTextSize(textsize:Float)
{
textView.textSize=textsize
}
 fun setTextColor(tcolor:Int)
 {
     textView.setTextColor(tcolor)
 }
fun setText(str:String)
{
    textView.text=str
}

}

But when i use this customView with width 70dp ,the text view does not fit center of CustomView and can anyone please tell me how to size textView according to width of layout