Cairo initializes a new graphics device that uses the cairo
graphics library for rendering. The current implementation produces
high-quality PNG, JPEG, TIFF bitmap files, high resolution PDF files
with embedded fonts, SVG graphics and PostScript files. It also
provides X11 and Windows interactive graphics devices. Unlike other
devices it supports all graphics features including alpha blending,
anti-aliasing etc.
CairoX11, CairoPNG, CairoPDF, CairoPS and
CairoSVG are convenience wrappers of Cairo that take the
same arguments as the corresponding device it replaces such as
X11, png, pdf, etc. Use of the Cairo
function is encouraged as it is more flexible than the wrappers.
Cairo(width = 640, height = 480, file="", type="png", pointsize=12,
bg = "transparent", canvas = "white", units = "px", dpi = "auto",
...)CairoX11(display=Sys.getenv("DISPLAY"), width = 7, height = 7,
pointsize = 12, gamma = getOption("gamma"), bg = "transparent",
canvas = "white", xpos = NA, ypos = NA, ...)
CairoPNG(filename = "Rplot%03d.png", width = 480, height = 480,
pointsize = 12, bg = "white", res = NA, ...)
CairoJPEG(filename = "Rplot%03d.jpeg", width = 480, height = 480,
pointsize = 12, quality = 75, bg = "white", res = NA, ...)
CairoTIFF(filename = "Rplot%03d.tiff", width = 480, height = 480,
pointsize = 12, bg = "white", res = NA, ...)
CairoPDF(file = ifelse(onefile, "Rplots.pdf","Rplot%03d.pdf"),
width = 6, height = 6, onefile = TRUE, family = "Helvetica",
title = "R Graphics Output", fonts = NULL, paper = "special",
encoding, bg, fg, pointsize, pagecentre, ...)
CairoSVG(file = ifelse(onefile, "Rplots.svg", "Rplot%03d.svg"),
width = 6, height = 6, onefile = TRUE, bg = "transparent",
pointsize = 12, ...)
CairoWin(width = 7, height = 7, pointsize = 12,
record = getOption("graphics.record"),
rescale = c("R", "fit", "fixed"), xpinch, ypinch, bg =
"transparent", canvas = "white", gamma = getOption("gamma"),
xpos = NA, ypos = NA, buffered = getOption("windowsBuffered"),
restoreConsole = FALSE, ...)
CairoPS(file = ifelse(onefile, "Rplots.ps", "Rplot%03d.ps"),
onefile = TRUE, family, title = "R Graphics Output", fonts = NULL,
encoding, bg, fg, width, height, horizontal, pointsize, paper,
pagecentre, print.it, command, colormodel)
The (invisible) return value is NULL if the device couldn't be created
or a Cairo object if successful. The vaule of the object is the
device number.
width of the plot area (also see units).
height of the plot area (also see units).
name of the file to be created or connection to write
to. Only PDF, PS and PNG types support connections. For X11
type file specifies the display name. If NULL or
"" a reasonable default will be chosen which is
"plot.type" for file-oriented types and value of the
DISPLAY environment variable for X11. For image types
the file name can contain printf-style formatting expecting
one integer parameter which is the page number, such as
"Rplot%03d.png". The page numbers start at one.
The filename is expanded using path.expand.
output type. This version of Cario supports "png", "jpeg"
and "tiff" bitmaps (png/tiff with transparent background), "pdf"
PDF-file with embedded fonts, "svg" SVG-file, "ps" PostScript-file,
"x11" X11 interactive window and "win" Windows graphics.
A special type "raster" creates an image back-end that produces no
actual output file but can be used in conjunction with any of
dev.capture(), grid.cap() or Cairo:::.image()
to create in-memory images.
Depending on the support of various backends in cairo graphics some
of the options may not be available for your system. See
Cairo.capabilities function.
initial text size (in points).
canvas color (must be opaque). The canvas is only used by devices that display graphics on a screen and the canvas is only visible only if bg is transparent.
plot background color (can include alpha-component or be transparent alltogether).
units for of the width and height
specifications. It can be any of "px" (pixels),
"in" (inches), "pt" (points), "cm"
(centimeters) or "mm" (millimeters).
DPI used for the conversion of units to pixels. If set to
"auto" the DPI resolution will be determined by the
back-end.
additional backend specific parameters (e.g. quality
setting for JPEG (0..100), compression for TIFF
(0,1=none, 5=LZW (default), 7=JPEG, 8=Adobe Deflate),
locator for a custom locator function in image back-ends)
The PDF back-end supports following additional arguments:
author, subject, creator, keywords,
create.date and modify.date. If specified, all of
the above must be single strings. The dates must be in
PDF-defined format, you can use something like
paste0("D:",gsub("[- :]","",.POSIXct(Sys.time(),"GMT"))),"Z")
to convert from POSIXct to PDF format. In addition, the
version argument (as documented in pdf)
can be either a string or a scalar real number. However,
the cairographics library only supports values 1.4 and 1.5.
All parameters
listed below are defined by the other devices are are used by
the wrappers to make it easier replace other devices by
Cairo. They are described in detail in the documentation
corresponding to the device that is being replaced.
X11 display, see X11
gamma correction
see X11
see X11
same as file in Cairo
resolution in ppi, see png, will
override dpi in Cairo if set to anything other
than NA or NULL. Note that cairographics does not
support tagging PNG output files with DPI so the raster image will
be produced with the dpi setting, but readers may render it at
some default dpi setting.
quality of the jpeg, see jpeg
logical: if true (the default) allow multiple
figures in one file (see pdf). false is currently
not supported by vector devices
font family, see pdf
see pdf
see pdf, ignored, Cairo
automatically detects and embeds fonts
see pdf (ignored, Cairo uses device dimensions)
see pdf (ignored, Cairo uses
native enconding except for symbols)
see pdf (ignored)
see pdf (ignored, Cairo
uses device dimensions and thus it is irrelevant)
see windows (ignored)
see windows (ignored)
see windows (ignored)
see windows (ignored)
see windows (ignored, Cairo
always uses cache buffer)
see windows (ignored)
The X11 backend is quite slow. The reason is the cairographics implementation of the backend, so we can't do much about it. It should be possible to drop cairographics' Xlib backend entirely and use image backend copied into an X11 window instead. We may try that in future releases.
TrueType (and OpenType) fonts are supported when this package is compiled against a cairo graphics library configured with FreeType and Fontconfig support. Therefore make sure have a cairo graphics library with all bells and whistles to get a good result.
R math symbols are supported, but require a TrueType "Symbol" font accessible to Cairo under that name.
CairoFonts
# very simple KDE
Cairo(600, 600, file="plot.png", type="png", bg="white")
plot(rnorm(4000),rnorm(4000),col="#ff000018",pch=19,cex=2) # semi-transparent red
dev.off() # creates a file "plot.png" with the above plot
# you can use any Cairo backend and get the same result
# vector, bitmap or on-screen
CairoPDF("plot.pdf", 6, 6, bg="transparent")
data(iris)
attach(iris)
plot(Petal.Length, rep(-0.03,length(Species)), xlim=c(1,7),
ylim=c(0,1.7), xlab="Petal.Length", ylab="Density",
pch=21, cex=1.5, col="#00000001", main = "Iris (yet again)",
bg=c("#ff000020","#00ff0020","#0000ff20")[unclass(Species)])
for (i in 1:3)
polygon(density(Petal.Length[unclass(Species)==i],bw=0.2),
col=c("#ff000040","#00ff0040","#0000ff40")[i])
dev.off()
## remove the example files if not in an interactive session
if (!interactive()) unlink(c("plot.png","plot.pdf"))
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