#1291 Different scaling of GPVAL_TERM_* variables.

[Christoph Bersch]

Hi,

I wanted to calculate the margins after a plot command. The right margin should be GPVAL_TERM_XMAX/(1.0*GPVAL_TERM_XSIZE).

But that works only for a few terminals, others have an internal oversampling, which gets included in e.g. GPVAL_TERM_XMAX, but not in e.g. GPVAL_TERM_XSIZE:

set terminal wxt
plot sin(x)
print sprintf('right margin at screen %f', GPVAL_TERM_XMAX/(1.0*GPVAL_TERM_XSIZE))

set terminal pdfcairo
set output '/dev/null'
plot sin(x)
print sprintf('right margin at screen %f', GPVAL_TERM_XMAX/(1.0*GPVAL_TERM_XSIZE))

That prints:

right margin at screen 0.962422
right margin at screen 0.047778

Tested with 4.6.0 and 4.7 (2013-09-23).

Would it be ok to scale GPVAL_TERM_XSIZE also by this oversampling factor, or would it break something?

Thanks,
Christoph

[Ethan Merritt]

As of today, 4.6 and 5.0 both report the current terminal scale factor in GPVAL_TERM_SCALE.

So right margin in fractional coordinates is
GPVAL_TERM_XMAX * GPVAL_TERM_SCALE * 1.0 / GPVAL_TERM_XSIZE

[Christoph Bersch]

Great, thank you for adding this. I attached a small patch to include the GPVAL_TERM_SCALE in an example in the docs.