Class "DevDescPtr" representing a C-level Graphics Device

Description

The DevDescPtr class represents a C-level data structure that corresponds to an existing R graphics device. If the device is active, R graphics commands will cause the device's graphical operators to be called.

We typically obtain a reference to the graphics device via the function graphicsDevice. It is also passed as an argument in each call to the R functions that operate as graphical primitives for the R-level graphics device.

We can query and set the state of the device treating it like a list in R. We can then access the individual fields, querying and setting their values using the regular R operators [[ and \$, e.g. dev$left and dev$right = 1000.

Objects from the Class

Objects of class DevDescPtr are created by the R graphics engine in C code and via the function graphicsDevice. We do not create them ourselves.

On occassion, it might be useful to convert the reference to the C structure to an R structure, i.e. one with the corresponding slots and the values as R vectors, etc. We use the DevDesc class for this and we can convert using the as function, e.g. as(dev, "DevDesc").

Slots

left:

Object of class "numeric"

right:

Object of class "numeric"

bottom:

Object of class "numeric"

top:

Object of class "numeric"

clipLeft:

Object of class "numeric"

clipRight:

Object of class "numeric"

clipBottom:

Object of class "numeric"

clipTop:

Object of class "numeric"

xCharOffset:

Object of class "numeric"

yCharOffset:

Object of class "numeric"

yLineBias:

Object of class "numeric"

ipr:

Object of class "numeric"

cra:

Object of class "numeric"

gamma:

Object of class "numeric"

canClip:

Object of class "Rboolean"

canChangeGamma:

Object of class "Rboolean"

canHAdj:

Object of class "integer"

startps:

Object of class "numeric"

startcol:

Object of class "integer"

startfill:

Object of class "integer"

startlty:

Object of class "integer"

startfont:

Object of class "integer"

startgamma:

Object of class "numeric"

deviceSpecific:

Object of class "raw"

displayListOn:

Object of class "Rboolean"

canGenMouseDown:

Object of class "Rboolean"

canGenMouseMove:

Object of class "Rboolean"

canGenMouseUp:

Object of class "Rboolean"

canGenKeybd:

Object of class "Rboolean"

gettingEvent:

Object of class "Rboolean"

hasTextUTF8:

Object of class "Rboolean"

wantSymbolUTF8:

Object of class "Rboolean"

useRotatedTextInContour:

Object of class "Rboolean"

Extends

Class "CStruct-class", directly.

Methods

"[["

signature(x = "DevDescPtr"): these methods allow one to query and set the values of the individual fiels

"$"

signature(x = "DevDescPtr"):

"[[<-"

signature(x = "DevDescPtr"):

"$<-"

signature(x = "DevDescPtr"):

"as"

signature(x = "DevDescPtr"): this method allows us to convert the C-level reference to an R-level DevDesc object using regular coercion, i.e. as(dev, "DevDesc").

Author(s)

Duncan Temple Lang

References

“The R Internals Manual”, R Development Core Team.

See Also

graphicsDevice

Examples

showClass("DevDesc")