Universal enhanced text mode!

[Ethan M. <merritt@u.washington.edu>]

I have abstracted the enhanced text mode from the postscript
terminal so that it can be used by other terminal types as well.
The core code moves into term.c. Each terminal wanting enhanced
text support must add 3  call-back routines to its TERM_TABLE.=20

Patch is on SourceForge (#842303).
Please check it out before I add it to CVS.

I have added reference implementations for
    post   gd   pdf   x11   dumb

The postscript output is character-for-character identical to
the output the original version.
Implementations for gd, pdf, and x11 are 99% complete.

Implementation of enhanced text for the dumb terminal is
admittedly frivolous, but I wanted to show that the new
mechanism is general enough to apply to any terminal driver.
The commented code for the ENHdumb_ callbacks can serve
as a model for other drivers.

Since the core code is shared, and was already present in
the original postscript driver, adding support to new drivers
does not substantially add to the size of gnuplot.=20
Enabling support for the dumb terminal, for example,
adds only 1500 bytes. More complicated terminals may need=20
larger call-back routines, of course, but the total size increase
of the gnuplot executable after adding the full patch is  about
0.7% on my machine.

A quick demo:

set term dumb enhanced
set title "Dumb is 10^2 less dumb than before"
set label 1 "Sum@_0^{big} fun(x_k)"
set label 1 at -.4, .4
set xrange [-1:0.5]
set xtics nomirror
set ytics nomirror
set tmargin 5
set border 3
plot x*x title "x^2"
#
pause -1


--=20
Ethan A Merritt       merritt@u.washington.edu
Biomolecular Structure Center Box 357742
University of Washington, Seattle, WA 98195