On Sat, 2006-09-16 at 20:26 +0100, Prof Brian Ripley wrote: > On Fri, 15 Sep 2006, Marc Schwartz (via MN) wrote: > > > On Fri, 2006-09-15 at 12:12 -0500, Kevin Wright wrote: > >> R has had the ability to generate pdfs with transparent colors for a > >> couple of years now using pdf(..., version="1.4"). > > I presume we are talking about translucency aka semitransparency (alpha > channel strictly between 0 and 1) here, introduced in R 2.0.0: support for > col="transparent" is much older. > > >> By default, Sweave uses just 'pdf' (without version 1.4), so a hack is > >> needed when using Sweave to create pdfs with transparent colors. See > >> http://tolstoy.newcastle.edu.au/R/help/04/11/6655.html > >> > >> I would find my work process simpler if R defaulted to generating PDFs > >> using version="1.4". The help page for R's pdf command says there is > >> a risk of some older pdf viewers not being able to view newer PDFs. > >> Does anyone have a feeling for how big a risk this is? I tried for a > >> while to search google for pdf metadata and the distribution of pdf > >> documents of different versions, but could find nothing useful to > >> report. > >> > >> The PDF 1.4 specification appears to have been published in November, 2001. > > Both C99 and Fortran 90 are older, and compilers for them are not yet > universally available. Many R users even use older OSes than that date. > Given Adobe's patchy support for non-popularist OSes, there are lots of > viewers from quite a while back out there (I found Acroread 4.05 on one of > our systems without looking very hard). According to Distiller, PDF 1.4 > was introduced in Acrobat 5, and 1.3 is still recommended as the lowest > common denominator. > > >> Is updating pdf() to version="1.4" feasible? > > In what sense: it does support that as an option? As the default, no. > > >> Discussions on this topic will be watched with interest. > >> > >> Kevin Wright > > > > Rather than globally changing R, wouldn't it be better to add another > > option to Sweave? > > > > For example, one can already specify 'height' and 'width' arguments for > > figures, why not a pdf version value? > > > > If I am reading it correctly, the relevant code from Sweave.R seems to > > be within the RweaveLatexRuncode() function: > > > > if(options$pdf){ > > pdf(file=paste(chunkprefix, "pdf", sep="."), > > width=options$width, height=options$height) > > > > Could this not be modified to something like: > > > > if(options$pdf){ > > pdf(file=paste(chunkprefix, "pdf", sep="."), > > width=options$width, height=options$height, > > version = pdf.version) > > > > Then the call within the .Rnw file could be something like: > > > > <<fig=true,width=6,height=4,pdf.version=1.4,include=false>>= > > or even > > \SweaveOpts{echo=FALSE, pdf.version=1.4}
Indeed. > > I am presuming that I am oversimplifying the changes here as I have not > > looked at the other code that would be affected by this change. > > You would need to set a default value, and that's non-trivial due to lack > of documentation of Sweave options (the internals need to be told that the > option is NOLOG (non-logical) and not numeric). Right, I had not reviewed the code where the options are actually set. > > Comments? > > That seems a much better approach, and I've added it for 2.4.0. > > Howver, I think the ideal solution is for the driver to keep track > of the features used and set the version number accordingly. I am not > sure why Paul did not do it that way (PDF viewers are supposed to ignore > non-conformant features), as if you use semitransparent colours you would > presumably like to see them where possible. Also implemented for 2.4.0, > but with a warning that setting pdf(version=1.4) will suppress. Terrific. Thank you! Regards, Marc ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
