matrix rotate wrong position

draw.kt

override fun onDraw(canvas: Canvas?) {
  contentBitmap.draw(canvas)

  // get rotate from matrix
  val matrixRotate = contentBitmapLayer.matrix.rotation

  // get contentBitmapLayer bounds from matrix
  val x1 = bitmapPoints[0]
  val y1 = bitmapPoints[1]
  val x2 = bitmapPoints[2]
  val y2 = bitmapPoints[3]
  val x3 = bitmapPoints[4]
  val y3 = bitmapPoints[5]
  val x4 = bitmapPoints[6]
  val y4 = bitmapPoints[7]

  // calculate mid point
  val contentMidPoint = calculateMidPoint()
  val tx = contentMidPoint.x - (rotateIcon.width / 2).toFloat()
  val ty = contentMidPoint.y - (rotateIcon.height / 2.toFloat())

  // rotateIcon draw start point
  val nx = (w - rotateIcon.width) / 2.0f
  val ny = rotateIcon.height + marginHeight

  // rotateIcon center translate contentBitmap center
  rotateIcon.matrix.setTranslate(tx, ty)
  rotateIcon.matrix.postRotate(matrixRotate, rotateIcon.width / 2.toFloat(), rotateIcon.height / 2.toFloat())
  rotateIcon.matrix.postTranslate(-tx, -ty)
  rotateIcon.matrix.postTranslate(x1 + nx, y1 - ny)

  rotateIcon.draw(canvas)
}