[Plplot-devel] Problems getting started with PLplot in an existing program

[Arjen M. <arj...@wl...>]

Hello,

I started using PLplot in an existing program (emulating another
graphical library).

I had a few problems, some of which were rather tricky to solve, but it
is working:

- The program has a graphical user-interface that manages all the
windows including
  the ones holding the graphics. Because plotting occurs in a pixmap,
rather than
  directly into a window, I needed a routine like plswin() that would
store the pixmap
  (the initialisation routines in the X window driver assume that they
have a true
  window). 
  I could solve this with some minor changes to the code

- I needed a routine to turn clipping on and off (easy enough, so I
added that to 
  my copy)

- I had severe problems getting the X Window driver to work properly
(and later to
  get the PostScript driver to work properly). The cause was
(apparently) the
  use of the global variable "plsc" in plP_setpxl() and plP_setphy() -
the address
  was different when the routines were called from within the shared
library than 
  the one I found via the debugger in the static library. When I made
clones of 
  these two routines and passed the argument "pls" directly, the problem
was gone.

  I am not familiar enough with the linking process to be much more
clear about 
  this, but apparently there were _two_ copies of (at least) the global
variable
  plsc around. Because the program contains Fortran sources as well, I
used a 
  Fortran compiler and linker to create the final executable.

Kind regards,

Arjen Markus