Android Canvas onDraw and Resize When ViewGroup was changed size ( synchronize )

Question

1. I draw this rectangle

2. I move to the left with controller in center. So webview in leftside was smaller than previous.

But My DrawingView wasn't smaller. <- That is problem.

xml

<FrameLayout>
 <WebView /> <- contents
 <DrawingView /> <- My Custom Drawing View ( onDraw )
</FrameLayout> 

When FrameLayout's size changed DrawingView Can't change size.

How to do??

My DrawingView : ViewGroup()

private val pathList = emptyList()

override fun onTouchEvent(event: MotionEvent?): Boolean {
                MotionEvent.ACTION_MOVE -> {
                    pathList.last().offsetList.add(touchX to touchY)
                    invalidate()
                    return true
                }
}
// save to pathList 


override fun onDraw(canvas: Canvas) {
        pathList.forEach {
           canvas.draw()
        }
}

//draw canvas with pathList

I tried

var ratioX = 1f

 override fun onSizeChanged(w: Int, h: Int, ow: Int, oh: Int) {
        ratioX = w.toFloat() / 2560
        super.onSizeChanged(w, h, ow, oh)
    }

  override fun onDraw(canvas: Canvas) {
    pathList.forEach{
       canvas.drawPath(it * ratioX)  // only X
    }
  }

but this solution drawing miss ( out of point in drawing )