The purpose of this chapter is to document the API for every internal C function in PLplot (other than language bindings) that is not part of the common API that has already been documented in Chapter 19 or elsewhere. The functions documented here are internal plplot functions. They are not intended for external use and may change between releases.
This chapter is a work that is just starting. There are many C functions in the code base that are not part of the common API, and we haven't even gotten to the point of listing them all. What gets documented here now is whatever C-explicit code we are trying to understand at the time.
Checks to see if any of the specified drivers have been
initialized. Function tests a space-delimited list of driver names to
see how many of the given drivers have been initialized, and how often.
The return code of the function is: 0 if no matching
drivers were found to have been initialized; -1 if
an error occurred allocating the internal buffer; or, a positive number
indicating the number of streams encountered that belong to drivers on
the provided list. This function invokes
internally to get a complete list of drivers that have been initialized
in order to compare with the driver names specified in the argument list