Spline approximation in a C++ project and more

Our C++ project converts TrueType text to DXF output. It is coded in C++ using VS2010 express. All now given functions must be preserved when the wanted extensions are introduced. Also the processing speed must be preserved. We will hand out the existing source only by request with NDA contract. 1) Now we have perfect clean splines in the output. We also want an approximated output of the splines as an option. Option means, output as splines or output as lines. The spline shall be transformed to a bunch of lines or a polyline. The calculation must take an allowed deviation from the original spline into account. This means, the count of lines per spline is dynamic. Example see picture. The approximation is also size dependent. It must be applied after the scaling (font size x factor) happened. A small-sized character must result in lesser lines than a large one. There are several readymade, ultrafast routines to find. 2) The project now uses DXFlib from Ribbonsoft. It is used to write simple elements, no blocks or other special things. The output is very simple text. We do not need any tables, just the pure entities. The output must be done with simple own routines. DXFLib must go away completely. A very basic DXF is enough.