key positioning problem

[Allin C. <cot...@wf...>]

Problem: with both the png (libgd) and cairopng terminals,
depending on the font selected the gnuplot "key" may overflow the
plot data region (even if the key terms are in no way excessive,
e.g. n <= 8 characters per term).

Example:
set term pngcairo font "FreeSans,8" size 680,400
set output 'test.png'
set key left top
plot x title "PRIME" w lines , \
 2*x title "UNEMP" w lines

In the resulting plot, the 'U' of "UNEMP" is vertically bisected
by the y axis.  The desired result is that all the key text
appears within the data area (i.e. to the right of the y axis);
and this is achieved if we change the first line of the plot file
to (for example)

set term pngcairo font "Vera,8" size 680,400

I'd be happy to try to work up a patch for this, but I'm having
difficulty figuring out where to start -- i.e., determining where
the left limit of the key block is computed, given the selected
font.

P.S., on further investigation this does not seems to be very
terminal-specific: I'm getting the same issue with the pdf,
pdfcairo, and 'post eps' terminal types.

-- 
Allin Cottrell
Department of Economics
Wake Forest University