cairo: Cairographics-based SVG, PDF and PostScript Graphics Devices

Description

Graphics devices for SVG, PDF and PostScript graphics files using the cairo graphics API.

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_MAX characters long, and may be truncated if not. See postscript for 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.

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.

Value

A plot device is opened: nothing is returned to the R interpreter.

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.

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).