Hi guys, am using QPainterPath to mimicing the bezier curve that you could achieve by using photoshop pen tool. Actually what I use doesn't matter in this question.
Now I got a issue: Before I insert a new bezier base point:
After I insert a new bezier base point on curve (Point C in this case):
As described in the second pix, If I want the curve stay in the same shape as before, I need to change the old bezier handle point D and E, also I need to know the x,y coordinate of new bezier handle point A and B. (I already knew the xy coordinate of the old point D, E and the new insert base point C.)