File based terminal behaviour

[Gareth W. <gw...@ca...>]

Hi,

I am relatively new to gnuplot and don't pretend to know anything about its
internals but some of the behaviour has been perplexing me. I can find very
little information on the intended behaviour or philospohy of the program.

I am developing a program that uses Octave (and hence gnuplot) to perform
engineering calculations and display the results in a web broswer.

To do this I need to output the plots to graphics file. The program is
attempting to keep MATLAB and Octave compatibility for interactive use of each
of the scripts, this riases issues of plot command ordering.

In an interactive terminal (x11 in our case) this is of no consequence but when
attempting to save the output to a file (I have used both png and SVG) the
ordering is critical as the first plot command encountered outputs to the file,
not allowing subsequent replots, clearing, adding of titles etc.

This behaviour is not encountered by multiplots which seem to be constructed in
a temporary terminal and then output once completed (signified by the unset
multiplot). I cannot get this behaviour to be replicated for single plots 
however.

From reading the postings here and on Soureforge I gather that the png terminal
is usually piped to Imagemagick's display, and that the behaviour of most other
file based terminals has been derrived from the png terminal's. It would appear
to me that the strength of a file based terminal is the production of a finished
plot, saved to a file for publishing, not real time viewing in an alternative
format. 

Would it not therefore make sense to have the option that once a user enters a 
'set term png', 'set output foo.png' to construct the plot as multiplot does,
and then output the completed plot once the 'set output' command closes the 
file?


Many thanks for your help,

Gareth