Environment: VC++ 6.0
One friend asks me how to draw a curve with a couple of mouse clicking. I know there is way called "cubic spline" to draw the curve based on the control points. I search through the internet, try to find out a piece of existing code. Unfortunately, though there are plenty of webpage talking about it, but few sites really give out the working code. I did found some Java code was presented with mess of the other UI handling code; however, I have not found any C/C++ code to finish this job so far. And I am not really a Java lover....
So I finish this piece of C++ header file called "spline.h". Which is easy to use and light weight. All you need to do is:
- Include this header file into your C++ file.
- Create a spline object.
- Pump in the control points.
- Gernearte a curve by a simple code line: spline.generate();
- Get the curve points to your array.
- Paint the curve to your DC.
This is so easy and handy for my future UI curve drawing, and you can also adjust the curve smoothness degree by setting a defined factor in spline.h.
A known bug: the control points should be more than one, if only one control point are pass to the spline, it will crash, I will appreciate it if anybody fix the bug.
Here is the code where I generate the curve, MFC CArray is used for my points array
//create a spline object Spline spline(m_ControlPoints.GetData(), m_ControlPoints.GetSize()); //generate a curve spline.Generate(); //get the curve points number m_CurvePoints.SetSize(spline.GetCurveCount()); //get the points number int PointCount = 0; spline.GetCurve(m_CurvePoints.GetData(), PointCount); //paint the curve UpdateDialog(pDC->m_hDC);