Implementing New Drawing Behavior

Now that you have added the CircleShape property to the CCircCtrl class and set its initial value in DoPropExchange, you can implement the new drawing behavior. To do this, you will make several additions to the CCircCtrl class code:

• Implement the GetDrawRect function to calculate the coordinates of the square region.
  
  
• Modify the OnDraw function to call GetDrawRect.
  
  
• Modify the OnCircleShapeChanged function to invalidate the control.