How to set a min value to a bezier path?

  bezier, c++, path, skia

I know I can draw a bezier path using control points but How can I set a value that if the path is in it then the path is a line that can not above the point?

let me explain for a normal bezier path is:
enter image description here

If I set the value the it will be:
enter image description here

it will not below the value.

Source: Windows Questions C++