how to find the radius using the center point only...
the only given point is the center point...
how to get or calculate for the radius...

Do you mean the radius of a circle? You can't get a radius from just its center point; that's not enough information. Or are you talking about something else?

If you have the centre point of a rendered circle you can find the radius by scanning pixels either horizontally or vertically until you find an edge, providing the circle is filled with a uniform colour and you can detect the edge by examining the pixels. I had to write something similar for someone to auto crop a few thousand New Yorker cartoons. The cartoons were all black and white and bounded by a rectangle surrounded by whitespace.

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.