cairo
Cairographics-based SVG, PDF and PostScript Graphics Devices
Graphics devices for SVG, PDF and PostScript graphics files using the cairo graphics API.
- Keywords
- device
Usage
svg(filename = if(onefile) "Rplots.svg" else "Rplot%03d.svg",
width = 7, height = 7, pointsize = 12,
onefile = FALSE, family = "sans", bg = "white",
antialias = c("default", "none", "gray", "subpixel"))cairo_pdf(filename = if(onefile) "Rplots.pdf" else "Rplot%03d.pdf",
width = 7, height = 7, pointsize = 12,
onefile = FALSE, family = "sans", bg = "white",
antialias = c("default", "none", "gray", "subpixel"),
fallback_resolution = 300)
cairo_ps(filename = if(onefile) "Rplots.ps" else "Rplot%03d.ps",
width = 7, height = 7, pointsize = 12,
onefile = FALSE, family = "sans", bg = "white",
antialias = c("default", "none", "gray", "subpixel"),
fallback_resolution = 300)
Arguments
- filename
the name of the output file. The page number is substituted if a C integer format is included in the character string, as in the default. (The result must be less than
PATH_MAXcharacters long, and may be truncated if not. Seepostscriptfor further details.) Tilde expansion is performed where supported by the platform.- width
the width of the device in inches.
- height
the height of the device in inches.
- pointsize
the default pointsize of plotted text (in big points).
- onefile
should all plots appear in one file or in separate files?
- family
one of the device-independent font families,
"sans","serif"and"mono", or a character string specify a font family to be searched for in a system-dependent way.On unix-alikes (incl.\ Mac), see the ‘Cairo fonts’ section in the help for
X11.- bg
the initial background colour: can be overridden by setting par("bg").
- antialias
string, the type of anti-aliasing (if any) to be used; defaults to
"default".- fallback_resolution
numeric: the resolution in dpi used when falling back to bitmap output. Prior to R 3.3.0 this depended on the cairo implementation but was commonly 300.
Details
SVG (Scalar Vector Graphics) is a W3C standard for vector graphics.
See http://www.w3.org/Graphics/SVG/. The output from svg
is SVG version 1.1 for onefile = FALSE (the default), otherwise
SVG 1.2. (Few SVG viewers are capable of displaying multi-page SVG
files.)
Note that unlike postscript and pdf,
cairo_pdf and cairo_ps sometimes record bitmaps
and not vector graphics. On the other hand, they can
(on suitable platforms) include a much wider range of UTF-8 glyphs,
and embed the fonts used.
The output produced by cairo_ps(onefile = FALSE) will be
encapsulated postscript on a platform with cairo >= 1.6.
R can be compiled without support for any of these devices: this will be reported if you attempt to use them on a system where they are not supported. They all require cairo version 1.2 (from 2006) or later.
If you plot more than one page on one of these devices and do not
include something like %d for the sequence number in
file (or set onefile = TRUE) the file will contain the
last page plotted.
There is full support of semi-transparency, but using this is one of
the things liable to trigger bitmap output (and will always do so for
cairo_ps).
Value
A plot device is opened: nothing is returned to the R interpreter.
Note
Cairo 1.2.4 (seen in Centos/RHEL 5) is known to give incorrect SVG output.
In principle these devices are independent of X11 (as is seen by their presence on Windows). But on a Unix-alike the cairo libraries may be distributed as part of the X11 system and hence that (on macOS, XQuartz) may need to be installed.
Anti-aliasing
Anti-aliasing is applied to both graphics and fonts. It is generally
preferable for lines and text, but can lead to undesirable effects for
fills, e.g.for image plots, and so is never used for
fills.
antialias = "default" is in principle platform-dependent, but
seems most often equivalent to antialias = "gray".
Conventions
This section describes the implementation of the conventions for graphics devices set out in the “R Internals Manual”.
The default device size is in pixels (
svg) or inches.Font sizes are in big points.
The default font family is Helvetica.
Line widths are multiples of 1/96 inch.
Circle radii have a minimum of 1/72 inch.
Colours are interpreted by the viewing application.
See Also
Devices, dev.print, pdf,
postscript
capabilities to see if cairo is supported.