trouble calling OpenCV cvFitLine

[JimPGH]

I am trying to use the OpenCV cvFitLine() function using the Python SWIG interface to OpenCV. My problem has to do with the fact that the last argument is a pointer to an array of four floats (to return the fitted line parameters). My first mindless attempt looked like this:

line = []
cv.cvFitLine(img, cv.CV_DIST_L2, 0, 0.01, 0.01, line)

This produced the error:

TypeError: in method 'cvFitLine', argument 6 of type 'float *'

After googling around bit, I decided that ctypes would give me the array pointer that I needed, so I modified my code as follows:

FourFloats = ctypes.c_float * 4
line = FourFloats()
cv.cvFitLine(img, cv.CV_DIST_L2, 0, 0.01, 0.01, ctypes.byref(line))

But this produced the same error. I'm stuck. Can someone please point me in the right direction?


Thanks...