contour path generation for spectrogram

[wang]

Hi list,

Qwt now can only generate line segments for contour plot. I came across this article, implementing the vector generation based on CONREC algorithm, http://apptree.net/conrec.htm. Unfortunately it is a Cocoa Object-C program and I can not directly test.

While I have made an naive try and found the following problems:
1. the generated paths often aren't closed. And the situation is better when zoomed in.
2. this algorithms does not include boundary conditions.

Since my Qwt knowledge is very limited. Uwe, are you interested? This would open more options in contour plot, such as filled contour, labeling contour lines.