| Line 27... |
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| 27 |
\item{paths}{A character vector of paths to PDF files, or a length-one
|
27 |
\item{paths}{A character vector of paths to PDF files, or a length-one
|
| 28 |
character vector naming a directory, when all \file{.pdf} files in
|
28 |
character vector naming a directory, when all \file{.pdf} files in
|
| 29 |
that directory will be used.}
|
29 |
that directory will be used.}
|
| 30 |
\item{qpdf}{Character string giving the path to the \command{qpdf}
|
30 |
\item{qpdf}{Character string giving the path to the \command{qpdf}
|
| 31 |
command. If empty, \command{qpdf} will not be used.}
|
31 |
command. If empty, \command{qpdf} will not be used.}
|
| 32 |
\item{gs_cmd}{Character string giving the path to the \I{GhostScript}
|
32 |
\item{gs_cmd}{Character string giving the path to the Ghostscript
|
| 33 |
executable, if that is to be used. On Windows this is the path to
|
33 |
executable, if that is to be used. On Windows this is the path to
|
| 34 |
\file{gswin32c.exe} or \file{gswin64c.exe}. If \code{""} (the
|
34 |
\file{gswin32c.exe} or \file{gswin64c.exe}. If \code{""} (the
|
| 35 |
default), the function will try to find a platform-specific path to
|
35 |
default), the function will try to find a platform-specific path to
|
| 36 |
\I{GhostScript} where required.}
|
36 |
Ghostscript where required.}
|
| 37 |
\item{gs_quality}{A character string indicating the quality required:
|
37 |
\item{gs_quality}{A character string indicating the quality required:
|
| 38 |
the options are \code{"none"} (so \I{GhostScript} is not used),
|
38 |
the options are \code{"none"} (so Ghostscript is not used),
|
| 39 |
\code{"printer"} (300dpi), \code{"ebook"} (150dpi) and
|
39 |
\code{"printer"} (300dpi), \code{"ebook"} (150dpi) and
|
| 40 |
\code{"screen"} (72dpi). Can be abbreviated.}
|
40 |
\code{"screen"} (72dpi). Can be abbreviated.}
|
| 41 |
\item{gs_extras}{An optional character vector of further options to be
|
41 |
\item{gs_extras}{An optional character vector of further options to be
|
| 42 |
passed to \I{GhostScript}.}
|
42 |
passed to Ghostscript.}
|
| 43 |
\item{verbose}{\code{\link{logical}} or non-negative integer indicating if
|
43 |
\item{verbose}{\code{\link{logical}} or non-negative integer indicating if
|
| 44 |
and how much of the compression utilities' output should be shown.}
|
44 |
and how much of the compression utilities' output should be shown.}
|
| 45 |
%--> format(*):
|
45 |
%--> format(*):
|
| 46 |
\item{x}{An object of class \code{"compactPDF"}.}
|
46 |
\item{x}{An object of class \code{"compactPDF"}.}
|
| 47 |
\item{ratio, diff}{Limits for reporting: files are only reported whose
|
47 |
\item{ratio, diff}{Limits for reporting: files are only reported whose
|
| Line 51... |
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| 51 |
}
|
51 |
}
|
| 52 |
\details{
|
52 |
\details{
|
| 53 |
This by default makes use of \command{qpdf}, available from
|
53 |
This by default makes use of \command{qpdf}, available from
|
| 54 |
\url{https://qpdf.sourceforge.io/} (including as a Windows binary) and
|
54 |
\url{https://qpdf.sourceforge.io/} (including as a Windows binary) and
|
| 55 |
included with the CRAN macOS distribution of \R. If \code{gs_cmd}
|
55 |
included with the CRAN macOS distribution of \R. If \code{gs_cmd}
|
| 56 |
is non-empty and \code{gs_quality != "none"}, \I{GhostScript} will used
|
56 |
is non-empty and \code{gs_quality != "none"}, Ghostscript will used
|
| 57 |
first, then \command{qpdf} if it is available. If
|
57 |
first, then \command{qpdf} if it is available. If
|
| 58 |
\code{gs_quality != "none"} and \code{gs_cmd} is \code{""}, an attempt
|
58 |
\code{gs_quality != "none"} and \code{gs_cmd} is \code{""}, an attempt
|
| 59 |
will be made to find a \I{GhostScript} executable.
|
59 |
will be made to find a Ghostscript executable.
|
| 60 |
|
60 |
|
| 61 |
\command{qpdf} and/or \command{gs_cmd} are run on all PDF files found,
|
61 |
\command{qpdf} and/or \command{gs_cmd} are run on all PDF files found,
|
| 62 |
and those which are reduced in size by at least 10\% and 10Kb are
|
62 |
and those which are reduced in size by at least 10\% and 10Kb are
|
| 63 |
replaced.
|
63 |
replaced.
|
| 64 |
|
64 |
|
| 65 |
The strategy of our use of \command{qpdf} is to (losslessly) compress
|
65 |
The strategy of our use of \command{qpdf} is to (losslessly) compress
|
| 66 |
both PDF streams and objects. \I{GhostScript} compresses streams and more
|
66 |
both PDF streams and objects. Ghostscript compresses streams and more
|
| 67 |
(including downsampling and compressing embedded images) and
|
67 |
(including downsampling and compressing embedded images) and
|
| 68 |
consequently is much slower and may lose quality (but can also produce
|
68 |
consequently is much slower and may lose quality (but can also produce
|
| 69 |
much smaller PDF files). However, quality \code{"ebook"} is perfectly
|
69 |
much smaller PDF files). However, quality \code{"ebook"} is perfectly
|
| 70 |
adequate for screen viewing and printing on laser printers.
|
70 |
adequate for screen viewing and printing on laser printers.
|
| 71 |
|
71 |
|
| Line 74... |
Line 74... |
| 74 |
so this is very unlikely to cause difficulties.
|
74 |
so this is very unlikely to cause difficulties.
|
| 75 |
|
75 |
|
| 76 |
Stream compression is what most often has large gains. Most PDF
|
76 |
Stream compression is what most often has large gains. Most PDF
|
| 77 |
documents are generated with object compression, but this does not
|
77 |
documents are generated with object compression, but this does not
|
| 78 |
seem to be the default for \I{MiKTeX}'s \command{pdflatex}. For some PDF
|
78 |
seem to be the default for \I{MiKTeX}'s \command{pdflatex}. For some PDF
|
| 79 |
files (and especially package vignettes), using \I{GhostScript} can
|
79 |
files (and especially package vignettes), using Ghostscript can
|
| 80 |
dramatically reduce the space taken by embedded images (often
|
80 |
dramatically reduce the space taken by embedded images (often
|
| 81 |
screenshots).
|
81 |
screenshots).
|
| 82 |
|
82 |
|
| 83 |
Where both \I{GhostScript} and \command{qpdf} are selected (when
|
83 |
Where both Ghostscript and \command{qpdf} are selected (when
|
| 84 |
\code{gs_quality != "none"} and both executables are found), they are
|
84 |
\code{gs_quality != "none"} and both executables are found), they are
|
| 85 |
run in that order and the size reductions apply to the total
|
85 |
run in that order and the size reductions apply to the total
|
| 86 |
compression achieved.
|
86 |
compression achieved.
|
| 87 |
}
|
87 |
}
|
| 88 |
|
88 |
|
| Line 97... |
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| 97 |
}
|
97 |
}
|
| 98 |
|
98 |
|
| 99 |
\note{
|
99 |
\note{
|
| 100 |
The external tools used may change in future releases.
|
100 |
The external tools used may change in future releases.
|
| 101 |
|
101 |
|
| 102 |
Frequently, updates to \I{GhostScript} have produced better compression (up
|
102 |
Frequently, updates to Ghostscript have produced better compression (up
|
| 103 |
to several times better), so if possible use the latest version available.
|
103 |
to several times better), so if possible use the latest version available.
|
| 104 |
}
|
104 |
}
|
| 105 |
|
105 |
|
| 106 |
\seealso{
|
106 |
\seealso{
|
| 107 |
\code{\link{resaveRdaFiles}}.
|
107 |
\code{\link{resaveRdaFiles}}.
|
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