\inputencoding{latin1}
\HeaderA{pdf}{PDF Graphics Device}{pdf}
\keyword{device}{pdf}
\begin{Description}\relax
\code{pdf} starts the graphics device driver for producing PDF
graphics.
\end{Description}
\begin{Usage}
\begin{verbatim}
pdf(file = ifelse(onefile, "Rplots.pdf", "Rplot%03d.pdf"),
    width, height, onefile, family, title, fonts, version,
    paper, encoding, bg, fg, pointsize, pagecentre, colormodel,
    useDingbats, useKerning)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{file}] a character string giving the name of the file.
For use with \code{onefile=FALSE} give a C integer format such
as \code{"Rplot\%03d.pdf"} (the default in that case).
(See \code{\LinkA{postscript}{postscript}} for further details.)

\item[\code{width, height}] the width and height of the graphics region in
inches.  The default values are \code{7}.
\item[\code{onefile}] logical: if true (the default) allow multiple figures
in one file.  If false, generate a file with name containing the page
number for each page.  Defaults to \code{TRUE}.
\item[\code{family}] the font family to be used, see
\code{\LinkA{postscript}{postscript}}.  Defaults to \code{"Helvetica"}.
\item[\code{title}] title string to embed as the \code{/Title} field in the
file.  Defaults to \code{"R Graphics Output"}.
\item[\code{fonts}] a character vector specifying \R{} graphics font family
names for fonts which will be included in the PDF file.  Defaults to
\code{NULL}.
\item[\code{version}] a string describing the PDF version that will be
required to view the output.  This is a minimum, and will be
increased (with a warning) if necessary.  Defaults to \code{"1.4"},
but see \sQuote{Details}.
\item[\code{paper}] the target paper size.  The choices are
\code{"a4"}, \code{"letter"}, \code{"legal"} (or \code{"us"}) and
\code{"executive"} (and these can be capitalized), or \code{"a4r"}
and \code{"USr"} for rotated (\sQuote{landscape}).
The default is \code{"special"}, which means that the \code{width}
and \code{height} specify the paper size.  A further choice is
\code{"default"}; if this is selected, the
papersize is taken from the option \code{"papersize"}
if that is set and as \code{"a4"} if it is unset or empty.
Defaults \code{"special"}.

\item[\code{encoding}] the name of an encoding file.  See
\code{\LinkA{postscript}{postscript}} for details.  Defaults to \code{"default"}.
\item[\code{bg}] the initial background color to be used.  Defaults to
\code{"transparent"}.
\item[\code{fg}] the initial foreground color to be used.  Defaults to
\code{"black"}.
\item[\code{pointsize}] the default point size to be used.  Strictly
speaking, in bp, that is 1/72 of an inch, but approximately in
points.  Defaults to \code{12}.
\item[\code{pagecentre}] logical: should the device region be centred on the
page? -- is only relevant for \code{paper != "special"}.  Defaults
to true.
\item[\code{colormodel}] a character string describing the color model:
currently allowed values are \code{"rgb"}, \code{"gray"} and
\code{"cmyk"}.  Defaults to \code{"rgb"}.
\item[\code{useDingbats}] logical.  Should small circles be rendered
\emph{via} the Dingbats font?  Defaults to \code{TRUE}, which produces
smaller and better output. Setting this to \code{FALSE} can work
around font display problems in broken PDF viewers.
See the \sQuote{Note} for a possible fix for such viewers.

\item[\code{useKerning}] logical.  Should kerning corrections be included in
setting text and calculating string widths?  Defaults to \code{TRUE}.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
All arguments except \code{file} default to values given by
\code{\LinkA{pdf.options}{pdf.options}()}.  The ultimate defaults are quoted in the
arguments section.

\code{pdf()} opens the file \code{file} and the PDF commands needed to
plot any graphics requested are sent to that file.

The \code{file} argument is interpreted as a C integer format as used
by \code{\LinkA{sprintf}{sprintf}}, with integer argument the page number.
The default gives files \file{Rplot001.pdf}, \dots, \file{Rplot999.pdf},
\file{Rplot1000.pdf}, \dots.

The \code{family} argument can be used to specify a PDF-specific
font family as the initial/default font for the device.

If a device-independent \R{} graphics font family is specified (e.g., via
\code{par(family=)} in the graphics package), the PDF device makes use
of the PostScript font mappings to convert the \R{} graphics font family
to a PDF-specific font family description.  (See the
documentation for \code{\LinkA{pdfFonts}{pdfFonts}}.)

\R{} does \emph{not} embed fonts in the PDF file, so it is only
straightforward to use mappings to the font families that can be
assumed to be available in any PDF viewer: \code{"Times"}
(equivalently \code{"serif"}), \code{"Helvetica"} (equivalently
\code{"sans"}) and \code{"Courier"} (equivalently \code{"mono"}).
Other families may be specified, but it is the user's responsibility
to ensure that these fonts are available on the system and third-party
software, e.g., Ghostscript, may be required to embed the fonts so
that the PDF can be included in other documents (e.g., LaTeX): see
\code{\LinkA{embedFonts}{embedFonts}}.  The URW-based families described for
\code{\LinkA{postscript}{postscript}} can be used with viewers
set up to use URW fonts, which is usual with those based on
\code{xpdf} or Ghostscript.
Since \code{\LinkA{embedFonts}{embedFonts}} makes use of Ghostscript, it should be
able to embed the URW-based families for use with other viewers.

See \code{\LinkA{postscript}{postscript}} for details of encodings, as the internal
code is shared between the drivers.  The native PDF encoding is given
in file \file{PDFDoc.enc}.

\code{pdf} writes uncompressed PDF.  It is primarily intended for
producing PDF graphics for inclusion in other documents, and
PDF-includers such as \code{pdftex} are usually able to handle
compression: there are a large number of PDF compression utilities
such as \samp{pdftk}.

The PDF produced is fairly simple, with each page being represented
as a single stream.  The \R{} graphics model does not distinguish
graphics objects at the level of the driver interface.

The \code{version} argument declares the version of PDF that gets
produced.  The version must be at least 1.4 for semi-transparent
output to be understood, and at least 1.3 if CID fonts are to be used:
if these features are used the version number will be increased (with
a warning).  Specifying a low version number is useful if you want to
produce PDF output that can be viewed on older or non-Adobe PDF
viewers.  (PDF 1.4 requires Acrobat 5 or later.)

Line widths as controlled by \code{par(lwd=)} are in multiples of
1/96 inch.  Multiples less than 1 are allowed.  \code{pch="."} with
\code{cex = 1} corresponds to a square of side 1/72 inch, which is
also the \sQuote{pixel} size assumed for graphics parameters such as
\code{"cra"}.

The \code{paper} argument sets the \code{/MediaBox} entry in the file,
which defaults to \code{width} by \code{height}.  If it is set to
something other than \code{"special"}, a device region of the
specified size is (by default) centred on the rectangle given by the
paper size: if either \code{width} or \code{height} is less
than \code{0.1} or too large to give a total margin of 0.5 inch, it is
reset to the corresponding paper dimension minus 0.5.  Thus if you
want the default behaviour of \code{\LinkA{postscript}{postscript}} use
\code{pdf(paper="a4r", width=0, height=0)} to centre the device region
on a landscape A4 page with 0.25 inch margins.

When the background colour is fully transparent (as is the initial
default value), the PDF produced does not paint the background.
Almost all PDF viewers will use a white canvas so the visual effect is
if the background were white.  This will not be the case when printing
onto coloured paper, though.
\end{Details}
\begin{Section}{Color models}
The default color model is RGB, and model \code{"gray"} maps RGB
colors to greyscale using perceived luminosity (biased towards green).
\code{"cmyk"} outputs in CMYK colorspace.  Nothing in \R{} specifies the
interpretation of the RGB or CMYK color spaces, and the simplest
possible conversion to CMYK is used
(\url{http://en.wikipedia.org/wiki/CMYK_color_model#Mapping_RGB_to_CMYK}).
\end{Section}
\begin{Section}{Conventions}
This section describes the implementation of the conventions for
graphics devices set out in the \dQuote{R Internals Manual}.

\Itemize{
\item The default device size is 7 inches square.
\item Font sizes are in big points.
\item The default font family is Helvetica.
\item Line widths are as a multiple of 1/96 inch, with no minimum. 
\item Circles of any radius are allowed.  Unless \code{useDingbats =
    FALSE}, opaque circles of less than 10 big
points radius are rendered using char 108 in the Dingbats font:
all semi-transparent and larger circles using a Bézier
curve for each quadrant.
\item Colours are interpreted by the viewing/printing application.
}
\end{Section}
\begin{Note}\relax
If you see problems with PDF output, do remember that the
problem is much more likely to be in your viewer than in \R.  Try
another viewer if possible.  Symptoms for which the viewer has been at
fault are apparent grids on image plots (turn off graphics
anti-aliasing in your viewer if you) and missing or incorrect glyphs
in text (viewers silently doing font substitution).

Unfortunately the default viewers on most Linux and Mac OS X systems
have these problems, and no obvious way to turn off graphics anti-aliasing.

Acrobat Reader does not use the fonts specified but rather emulates
them from multiple-master fonts.  This can be seen in imprecise
centering of characters, for example the multiply and divide signs in
Helvetica.  This can be circumvented by embedding fonts where
possible.  Most other viewers substitute fonts, e.g. URW fonts for the
standard Helvetica and Times fonts, and these too often have different
font metrics from the true fonts.

Acrobat Reader 5.x and later can be extended by support for Asian and
(so-called) Central European fonts, and these will be needed for the
full use of encodings other than Latin-1.  See
\url{http://www.adobe.com/products/acrobat/acrrasianfontpack.html} for
Reader 6.x to 8.x, and \url{http://www.adobe.com/downloads/updates}
for 9.x.

On some systems the default plotting character \code{pch = 1} is
displayed in some PDF viewers incorrectly as a \code{"q"}
character.  (These seem to be viewers based on the \samp{poppler} PDF
rendering library). This may be due to incorrect or incomplete mapping
of font names to those used by the system.  Adding the following lines
to \file{\textasciitilde{}/.fonts.conf} or \file{/etc/fonts/local.conf} may circumvent
this problem.
\begin{alltt}
<alias binding="same">
       <family>ZapfDingbats</family>
       <accept><family>Dingbats</family></accept>
</alias>
\end{alltt}
\end{Note}
\begin{SeeAlso}\relax
\code{\LinkA{pdfFonts}{pdfFonts}}, \code{\LinkA{pdf.options}{pdf.options}},
\code{\LinkA{embedFonts}{embedFonts}},
\code{\LinkA{Devices}{Devices}},
\code{\LinkA{postscript}{postscript}}.
\code{\LinkA{cairo\_pdf}{cairo.Rul.pdf}} and (on Mac OS X only) \code{\LinkA{quartz}{quartz}}
for other devices that can produce PDF.

More details of font families and encodings and especially handling
text in a non-Latin-1 encoding and embedding fonts can be found in

Paul Murrell and Brian Ripley (2006) Non-standard fonts in PostScript
and PDF graphics. \emph{R News}, 6(2):41--47.
\url{http://cran.r-project.org/doc/Rnews/Rnews_2006-2.pdf}.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
## Not run: 
## Test function for encodings
TestChars <- function(encoding="ISOLatin1", ...)
{
    pdf(encoding=encoding, ...)
    par(pty="s")
    plot(c(-1,16), c(-1,16), type="n", xlab="", ylab="",
         xaxs="i", yaxs="i")
         title(paste("Centred chars in encoding", encoding))
    grid(17, 17, lty=1)
    for(i in c(32:255)) {
        x <- i %% 16
        y <- i %/% 16
        points(x, y, pch=i)
    }
    dev.off()
}
## there will be many warnings.
TestChars("ISOLatin2")
## this does not view properly in older viewers.
TestChars("ISOLatin2", family="URWHelvetica")
## works well for viewing in gs-based viewers, and often in xpdf.
## End(Not run)\end{ExampleCode}
\end{Examples}

