R: Windows Graphics Devices

windows {grDevices}

R Documentation

Windows Graphics Devices

Description

Available only on Windows. A graphics device is opened. For windows, win.graph, x11 and X11 this is a window on the current Windows display: the multiple names are for compatibility with other systems. win.metafile prints to a file and win.print to the Windows print system.

Usage

windows(width, height, pointsize, record, rescale, xpinch, ypinch,
        bg, canvas, gamma, xpos, ypos, buffered, title,
        restoreConsole, clickToConfirm, fillOddEven,
        family, antialias)

win.graph(width, height, pointsize)

win.metafile(filename = "", width = 7, height = 7, pointsize = 12,
             family, restoreConsole = TRUE,
             xpinch = NA_real_, ypinch = NA_real_)

win.print(width = 7, height = 7, pointsize = 12, printer = "",
          family, antialias, restoreConsole = TRUE)

Arguments

`width`, `height`	the (nominal) width and height of the canvas of the plotting window in inches. Default `7`.
`pointsize`	the default pointsize of plotted text, interpreted as big points (1/72 inch). Values are rounded to the nearest integer: values less than or equal to zero are reset to `12`, the default.
`record`	logical: sets the initial state of the flag for recording plots. Default `FALSE`.
`rescale`	character, one of `c("R", "fit", "fixed")`. Controls the action for resizing of the device. Default `"R"`. See the ‘Resizing options’ section.
`xpinch`, `ypinch`	double. Pixels per inch, horizontally and vertically. Default `NA_real_`, which means to take the value from Windows.
`bg`	color. The initial background color. Default `"transparent"`.
`canvas`	color. The color of the canvas which is visible when the background color is transparent. Should be a solid color (and any alpha value will be ignored). Default `"white"`.
`gamma`	gamma correction fudge factor. Colours in R are sRGB; if your monitor does not conform to sRGB, you might be able to improve things by tweaking this parameter to apply additional gamma correction to the RGB channels. By default 1 (no additional gamma correction).
`xpos`, `ypos`	integer. Position of the top left of the window, in pixels. Negative values are taken from the opposite edge of the monitor. Missing values (the default) mean take the default from the ‘Rconsole’ file, which in turn defaults to `xpos = -25, ypos = 0`: this puts the right edge of the window 25 pixels from the right edge of the monitor.
`buffered`	logical. Should the screen output be double-buffered? Default `TRUE`.
`title`	character string, up to 100 bytes. With the default `""`, a suitable title is created internally. A C-style format for an integer will be substituted by the device number.
`filename`	the name of the output file: it will be an enhanced Windows metafile, usually given extension ‘.emf’ or ‘.wmf’. Up to 511 characters are allowed. The page number is substituted if an integer format is included in the character string (see `pdf` for further details) and tilde-expansion (see `path.expand`) is performed. (The result must be less than 600 characters long.) The default, `""`, means the clipboard.
`printer`	The name of a printer as known to Windows. The default causes a dialog box to come up for the user to choose a printer.
`restoreConsole`	logical: see the ‘Details’ below. Defaults to `FALSE` for screen devices.
`clickToConfirm`	logical: if true confirmation of a new frame will be by clicking on the device rather than answering a problem in the console. Default `TRUE`.
`fillOddEven`	logical controlling the polygon fill mode: see `polygon` for details. Default `TRUE`.
`family`	A length-one character vector specifying the default font family. See section ‘Fonts’.
`antialias`	A length-one character vector, requesting control over font antialiasing. This is partially matched to `"default"`, `"none"`, `"cleartype"` or `"gray"`. See the ‘Fonts’ section.

Details

All these devices are implemented as variants of the same device.

All arguments of windows have defaults set by windows.options: the defaults given in the arguments section are the defaults for the defaults. These defaults also apply to the internal values of gamma, xpinch, ypinch, buffered, restoreConsole and antialias for win.graph, x11 and X11.

The size of a window is computed from information provided about the display: it depends on the system being configured accurately. By default a screen device asks Windows for the number of pixels per inch. This can be overridden (it is often wrong) by specifying xpinch and ypinch, most conveniently via windows.options. For example, a 13.3 inch 1280x800 screen (a typical laptop display) was reported as 96 dpi even though it is physically about 114 dpi. These arguments may also be useful to match the scale of output to the size of a metafile (which otherwise depends on the system being configured accurately).

The different colours need to be distinguished carefully. Areas outside the device region are coloured in the Windows application background colour. The device region is coloured in the canvas colour. This is over-painted by the background colour of a plot when a new page is called for, but that background colour can be transparent (and is by default). One difference between setting the canvas colour and the background colour is that when a plot is saved the background colour is copied but the canvas colour is not. The argument bg sets the initial value of par("bg") in base graphics and gpar("fill") in grid graphics

Recorded plot histories are of class "SavedPlots". They have a print method, and a subset method. As the individual plots are of class "recordedplot" they can be replayed by printing them: see recordPlot. The active plot history is stored in variable .SavedPlots in the workspace.

When a screen device is double-buffered (the default) the screen is updated 100ms after last plotting call or every 500ms during continuous plotting. These times can be altered by setting options("windowsTimeout") to a vector of two integers before opening the device.

Line widths as controlled by par(lwd =) are in multiples of 1/96inch. Multiples less than 1 are allowed, down to one pixel width.

For win.metafile only one plot is allowed per file, and Windows seems to disallow reusing the file. So the only way to allow multiple plots is to use a parametrized filename as in the example. If the filename is omitted (or specified as ""), the output is copied to the clipboard when the device is closed.

The restoreConsole argument is a temporary fix for a problem in the current implementation of several Windows graphics devices, and is likely to be removed in an upcoming release. If set to FALSE, the console will not receive the focus after the new device is opened.

There is support for semi-transparent colours of lines, fills and text on the screen devices. These work for saving (from the ‘File’ menu) to PDF, PNG, BMP, JPEG and TIFF, but will be ignored if saving to Metafile and PostScript. Limitations in the underlying Windows API mean that a semi-transparent object must be contained strictly within the device region (allowing for line widths and joins).

Value

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

Resizing options

If a screen device is re-sized, the default behaviour ("R") is to redraw the plot(s) as if the new size had been specified originally. Using "fit" will rescale the existing plot(s) to fit the new device region, preserving the aspect ratio. Using "fixed" will leave the plot size unchanged, adding scrollbars if part of the plot is obscured.

A graphics window will never be created at more than 85% of the screen width or height, but can be resized to a larger size. For the first two rescale options the width and height are rescaled proportionally if necessary, and if rescale = "fit" the plot(s) are rescaled accordingly. If rescale = "fixed" the initially displayed portion is selected within these constraints, separately for width and height. In MDI mode, the limit is 85% of the MDI client region.

Using strwidth or strheight after a window has been rescaled (when using "fit") gives dimensions in the original units, but only approximately as they are derived from the metrics of the rescaled fonts (which are in integer sizes)

The displayed region may be bigger than the ‘paper’ size, and area(s) outside the ‘paper’ are coloured in the Windows application background colour. Graphics parameters such as "din" refer to the scaled plot if rescaling is in effect.

Fonts

The fonts used for text drawn in a Windows device may be controlled in two ways. The file ‘R_HOME\etc\Rdevga’ can be used to specify mappings for par(font =) (or the grid equivalent). Alternatively, a font family can be specified by a non-empty family argument (or by e.g. par(family =) in the graphics package) and this will be used for fonts 1:4 via the Windows font database (see windowsFonts).

How the fonts look depends on the antialiasing settings, both through the antialias argument and the machine settings. These are hints to Windows GDI that may not be able to be followed, but antialias = "none" should ensure that no antialiasing is used. For a screen device the default depends on the machine settings: it will be "cleartype" if that has been enabled. Note that the greyscale antialiasing that is used only for small fonts (below about 9 pixels, around 7 points on a typical display).

When accessing a system through Remote Desktop, both the Remote Desktop settings and the user's local account settings are relevant to whether antialiasing is used.

Some fonts are intended only to be used with ClearType antialiasing, for example the Meiryo Japanese font.

Conventions

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, although this is often incorrectly implemented by Windows: see ‘Details’.
Font sizes are in big points.
The default font family is Arial.
Line widths are as a multiple of 1/96 inch, with a minimum of one pixel.
The minimum radius of a circle is 1 pixel.
pch = "." with cex = 1 corresponds to a rectangle of sides the larger of one pixel and 0.01 inch.
Colours are interpreted via the unprofiled colour mapping of the graphics card – this is assumed to conform to sRGB.

Note

x11(), X11() and win.graph() are simple wrappers calling windows(), and mainly exist for compatibility reasons.

Further, x11() and X11() have their own help page for Unix-alikes (where they also have more arguments).

Examples

## Not run: ## A series of plots written to a sequence of metafiles
if(.Platform$OS.type == "windows")
   win.metafile("Rplot%02d.wmf", pointsize = 10)

## End(Not run)

[Package grDevices version 4.5.0 Index]