Re: [9fans] psutils et al

[Theo Honohan <theoh@chiark.greenend.org.uk>]

nemo@gsyc.escet.urjc.es wrote:
>
> I read the gs documentation and seems that viewers that
> do the rotate thing are using postscript routines to change
> the page orientation, so I think that unless page could go the
> same way, there is no simple gs option to rotate the ps.

In fact, the standard X11 viewers (ghostview and, much better, GV)
change the orientation of the display by setting the GHOSTVIEW
environment variable.  gs's X11 display driver reads a number of
configuration options from the value of GHOSTVIEW before drawing.
(see gdevxini.c)

I don't think trying to change the orientation with a ps prologue
will be reliable in all cases.  mpage does a good job, but it has
its shortcomings:

http://bugs.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=25170


> In any case, I'd say that's  the job of a filter and not of
> page.

It's clear that we should be able to control the orientation in which
the page is displayed independently of the internal coordinate
system and transformation matrix used by the postscript interpreter.

I'm not sure whether managing the display orientation should be part
of "page"'s job.  Judging from the presence of the "u" option, and by
analogy with the way I seem to use real photos and sheets of paper,
I'm inclined to think that it is.

Theo