R devel - Aug 2000 - Re: [R] problem clipping R postscript plots within latex (PR#625)

On Wed, 2 Aug 2000 p.dalgaard@biostat.ku.dk wrote:
> Martin Maechler <maechler@stat.math.ethz.ch> writes:
> 
> > (from R-help)
> >     PD> Stephen Eglen <stephen@cogsci.ed.ac.uk> writes:
> > 
> >     >  > > generated by R into a latex document. 
Specifically, the latex package
> >     >  > > graphicsx allow you to specify the bounding box of
the postscript
> >     >  > > file, so that you can just show _part_ of the
postscript file if you
> >     >  > > tell it to also clip the area outside of the
bounding box.
> >     > ...
> >     >  > Ow. This stems from the use of "initclip" in
the R-generated PS. One
> >     >  > shouldn't do that, one should bracket clipped
graphics within
> >     >  > gsave/grestore instead. Sounds a bit tricky to get
right.
> >     > 
> >     > Thanks.  To solve my current problem, I changed the
definition of the
> >     > `cl' operator in the postscript file to:
> >     > 
> >     > /cl  { gsave initclip newpath 3 index 3 index moveto 1 index
> >     >        4 -1 roll lineto  exch 1 index lineto lineto
> >     >        closepath clip grestore newpath } def
> >     > 
> >     > [i.e. just adding the gsave ... grestore pair]
> >     > 
> >     > Whether this is the proper solution though is another
matter...
> > 
> >     PD> It isn't. It grestore-s before actually plotting the
stuff that
> >     PD> needs to be clipped, so effectively you just disabled
R's
> >     PD> clipping. A better way would be to start the plotting with
a "gs"
> >     PD> and have
> > 
> >     /cl  { gr gs newpath 3 index 3 index moveto 1 index
> > 	   4 -1 roll lineto  exch 1 index lineto lineto
> > 	   closepath clip newpath } def
> > 
> >     PD> and end everything with a "gr". Not too sure that
is perfectly
> >     PD> safe, though...
> > 
> > Are you working on this, Peter?
> > Otherwise, "R-bugs" should probably get about the above
report..
> 
> Done... 
Just to note that ?postscript says

    The postscript produced by R is EPS (Encapsulated PostScript)
    compatible,

yet initclip is not allowed in EPS files (PostScript Language Reference
Manual, 2nd edition).  I think the statement was possibly true once ....

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595


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ripley@stats.ox.ac.uk writes:
> > >     /cl  { gr gs newpath 3 index 3 index moveto 1 index
> > > 	   4 -1 roll lineto  exch 1 index lineto lineto
> > > 	   closepath clip newpath } def
> > > 
> > >     PD> and end everything with a "gr". Not too sure
that is perfectly
> > >     PD> safe, though...
>     The postscript produced by R is EPS (Encapsulated PostScript)
>     compatible,
> 
> yet initclip is not allowed in EPS files (PostScript Language Reference
> Manual, 2nd edition).  
Exactly. 
> I think the statement was possibly true once ....
I don't think so. This is a design problem.

Unfortunately, the simple fix above doesn't seem to work [for rather
foreseeable reasons]. mosaicplot() seems to crash ghostview and even
plot(1:10) comes out without axis titles. 

The latter item occurs because we're doing

clip(region1)
set font
draw text
clip(region2)
draw more text in same font

but restoring the graphics context prior to the first clipping 
requires the font to be set once again. And there are probably many
similar problems. Sigh. 

Paul, are you around?

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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