| compactPDF {tools} | R Documentation |
Re-save PDF files (especially vignettes) more compactly.
Support function for R CMD build --compact-vignettes.
compactPDF(paths, qpdf = Sys.getenv("R_QPDF", "qpdf"),
gs_cmd = Sys.getenv("R_GSCMD", ""),
gs_quality = Sys.getenv("GS_QUALITY", "none"),
gs_extras = character())
paths |
A character vector of paths to PDF files, or a length-one character vector naming a directory, when all ‘.pdf’ files in that directory will be used. |
qpdf |
Character string giving the path to the |
gs_cmd |
Character string giving the path to the GhostScript executable, if that is to be used. On Windows this is the path to ‘gswin32c.exe’ or ‘gswin64c.exe’. |
gs_quality |
A character string indicating the quality required:
the options are |
gs_extras |
An optional character vector of further options to be passed to GhostScript. |
This by default makes use of qpdf, available from
http://qpdf.sourceforge.net/ (including as a Windows binary) and
included with the CRAN Mac OS X distribution of R. If gs_cmd
is non-empty and gs_quality != "none", GhostScript will used
instead. If gs_quality != "none" and gs_cmd is empty,
an attempt will be made to find a GhostScript executable.
qpdf or gs_cmd is run on all PDF files found, and
those which are reduced in size by at least 10% and 10Kb are
replaced.
The strategy of our use of qpdf is to (losslessly) compress
both PDF streams and objects. Ghostscript compresses streams and more
(including downsampling and compressing embedded images) and
consequently is much slower and may lose quality (but can also produce
much smaller PDF files). However, quality "ebook" is perfectly
adequate for screen viewing and printing on laser printers.
Where PDF files are changed they will become PDF version 1.5 files: these have been supported by Acrobat Reader 6 since 2003, so this is very unlikely to cause difficulties.
Stream compression is what most often has large gains: R's
pdf device prior to R 2.14.0 did not use it, and
older vignette PDFs often benefit from being re-generated. Most PDF
documents are generated with object compression, but this does not
seem to be the default for MiKTeX's pdflatex.
An object of class c("compactPDF", "data.frame") with
format and print methods. This has two columns, the old
and new sizes in bytes for the files that were changed.
The external tools used may change in future releases.
resaveRdaFiles.
Many other (and sometimes more effective) tools to compact PDF files are available, including Adobe Acrobat (not Reader). See the ‘Writing R Extensions’ manual.