| x11 {grDevices} | R Documentation |
X11 starts a graphics device driver for the X Window System
(version 11). This can only be done on machines/accounts that have
access to an X server.
x11 is recognized as a synonym for X11.
X11(display = "", width, height, pointsize, gamma, bg, canvas,
fonts, xpos, ypos, title, type, antialias)
X11.options(..., reset = FALSE)
display |
the display on which the graphics window will appear. The default is to use the value in the user's environment variable DISPLAY. This is ignored (with a warning) if an X11 device is already open on another display. |
width, height |
the width and height of the plotting window, in
inches. If |
pointsize |
the default pointsize to be used. Defaults to |
gamma |
the gamma correction factor. This value is used
to help ensure that the colours perceived are linearly related to
RGB values (see |
bg |
colour, the initial background colour. Default
|
canvas |
colour. The colour of the canvas, which is visible only
when the background colour is transparent. Should be a solid colour
(and any alpha value will be ignored). Default |
fonts |
X11 font description strings into which weight, slant and size will be substituted. There are two, the first for fonts 1 to 4 and the second for font 5, the symbol font. See section ‘Fonts’. |
xpos, ypos |
integer: initial position of the top left corner of the
window, in pixels. Negative values are from the opposite corner,
e.g. |
title |
character string, up to 100 bytes. With the default,
|
type |
character string, one of |
antialias |
for cairo types, the type of anti-aliasing (if any)
to be used. One of |
reset |
logical: should the defaults be reset to their defaults? |
... |
Any of the arguments to |
The defaults for all of the arguments of X11 are set by
X11.options: the ‘Arguments’ section gives the
‘factory-fresh’ defaults.
The initial size and position are only hints, and may not be acted on by the window manager. Also, some systems (especially laptops) are set up to appear to have a screen of a different size to the physical screen.
Option type selects between two separate devices: R can be
built with support for neither, type = "Xlib" or both. Where
both are available, types "cairo" and "nbcairo" offer
antialiasing of text and lines.
translucent colours.
scalable text, including to sizes like 4.5 pt.
full support for UTF-8, so on systems with suitable fonts you can plot in many languages on a single figure (and this will work even in non-UTF-8 locales). The output should be locale-independent.
type = "nbcairo" is the same device as type="cairo"
without buffering: which is faster will depend on the X11
connection. Both will be slower than type = "Xlib", especially
on a slow X11 connection as all the rendering is done on the machine
running R rather than in the X server.
All devices which use an X11 server (including the type =
"Xlib" versions of bitmap devices such as png) share
internal structures, which means that they must use the same
display and visual. If you want to change display, first close
all such devices.
This section applies only to type = "Xlib".
An initial/default font family for the device can be specified via
the fonts argument, but if a device-independent R graphics font
family is specified (e.g., via par(family=) in the graphics
package), the X11 device makes use of the X11 font database (see
X11Fonts) to convert the R graphics font family to an
X11-specific font family description.
X11 chooses fonts by matching to a pattern, and it is quite possible
that it will choose a font in the wrong encoding or which does not
contain glyphs for your language (particularly common in
iso10646-1 fonts).
The fonts argument is a two-element character vector, and the
first element will be crucial in successfully using
non-Western-European fonts. Settings that have proved useful include
"-*-mincho-%s-%s-*-*-%d-*-*-*-*-*-*-*" for CJK languages and
"-cronyx-helvetica-%s-%s-*-*-%d-*-*-*-*-*-*-*" for Russian.
For UTF-8 locales, the XLC_LOCALE databases provide mappings
between character encodings, and you may need to add an entry for your
locale (e.g. Fedora Core 3 lacked one for ru_RU.utf8).
The cairo-based device works directly with font family names such as
"Helvetica" which should be selected by par or
gpar. There are mappings for the three
device-independent font families, "sans" for a sans-serif font
(to "Helvetica"), "serif" for a serif font (to
"Times") and "mono" for a monospaced font (to
"Courier").
The font selection is handled by Pango (usually) or
cairo (on Mac OS X and perhaps elsewhere). Both make use of
fontconfig (http://wwww.fontconfig.org) to select fonts
and so the results depend on the fonts installed on the system running
R – setting the environmnent variable FC_DEBUG to 1 allows
some tracing of the selection process.
This works best when high-quality scalable fonts are installed, usually in Type 1 or TrueType formats: see the “R Installation and Administration Manual” for advice on how to obtain and install such fonts.
The standard X11 resource geometry can be used to specify the
window position and/or size, but will be overridden by values
specified as arguments or non-NA defaults set in
X11.options. The class looked for is R_x11. Note that
the resource specifies the width and height in pixels and not in
inches. See for example
http://web.mit.edu/answers/xwindows/xwindows_resources.html and
perhaps ‘man X’ (or http://www.xfree86.org/current/X.7.html).
An example line in ‘~/.Xresources’ might be
R_x11*geometry: 900x900-0+0
which specifies a 900 x 900 pixel window at the top right of the screen.
X11 supports several ‘visual’ types, and nowadays almost all
systems support ‘truecolor’ which X11 will use by
default. This uses a direct specification of any RGB colour up to the
depth supported (usually 8 bits per colour). Other visuals make use
of a palette to support fewer colours, only grays or even only
black/white. The palette is shared between all X11 clients, so it can
be necessary to limit the number of colours used by R.
Cairo-based devices currently support only ‘truecolor’ visuals. (Cairo 1.6 will support other visuals.)
The default for type="Xlib" is to use the best possible colour
model for the visual of the X11 server. This can be overridden by the
colortype argument of X11.options. Note: All
X11 and type = "Xlib" bmp, jpeg,
png and tiff devices share a colortype which is
set when the first device to be opened. To change the
colortype you need to close all open such devices, and
then use X11.options(colortype=).
The colortype types are tried in the order "true",
"pseudo", "gray" and "mono" (black or white
only). The values "pseudo" and "pseudo.cube" provide
colour strategies for a pseudocolor visual. The first strategy
provides on-demand colour allocation which produces exact colours until
the colour resources of the display are exhausted (when plotting will
fail). The second allocates (if possible) a standard colour cube, and
requested colours are approximated by the closest value in the cube.
With colortype equal to "pseudo.cube" or "gray"
successively smaller palettes are tried until one is completely
allocated. If allocation of the smallest attempt fails the device will
revert to "mono". For "gray" the search starts at 256
grays for a display with depth greater than 8, otherwise with half
the available colours. For "pseudo.cube" the maximum cube size
is set by X11.options(maxcolorsize=) and defaults to
256. With that setting the largest cube tried is 4 levels each for
RGB, using 64 colours in the palette.
Anti-aliasing is only supported for cairo-based devices, and applies to
graphics and to 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".
This section describes the implementation of the conventions for graphics devices set out in the “R Internals Manual”.
The default device size is 7 inches square.
Font sizes are in big points.
The default font family is Helvetica.
Line widths in 1/96 inch, minimum one pixel for type =
"Xlib", 0.01 otherwise.
For type = "Xlib" circle radii are in pixels with
minimum one.
Colours are interpreted by the X11 server, normally in a fair approximation to sRGB.
Devices, X11Fonts, savePlot.
## Not run:
## put something this is your .Rprofile to customize the defaults
setHook(packageEvent("grDevices", "onLoad"),
function(...) grDevices::X11.options(width=8, height=6, xpos=0,
pointsize=10))
## End(Not run)