deviceLoc

0th

Percentile

Convert Viewport Location to Device Location

These functions take a pair of unit objects and convert them to a pair of device locations (or dimensions) in inches.

Keywords
dplot
Usage
deviceLoc(x, y, valueOnly = FALSE)
deviceDim(w, h, valueOnly = FALSE)
Arguments
x, y, w, h

A unit object.

valueOnly

A logical indicating. If TRUE then the function does not return a unit object, but rather only the converted numeric values.

Details

These functions differ from the functions like convertX() because they convert from the coordinate systems within a viewport to inches on the device (i.e., from one viewport to another) and because they only deal with pairs of values (locations or dimensions).

The functions like convertX() convert between different units within the same viewport and convert along a single dimension.

Value

A list with two components, both of which are unit object in inches (unless valueOnly is TRUE in which case both components are numeric).

Warning

The conversion is only valid for the current device size. If the device is resized then at least some conversions will become invalid.

Furthermore, the returned value only makes sense with respect to the entire device (i.e., within the context of the root viewport).

library(grid) # NOT RUN { ## A tautology grid.newpage() pushViewport(viewport()) deviceLoc(unit(1, "inches"), unit(1, "inches")) ## Something less obvious grid.newpage() pushViewport(viewport(width=.5, height=.5)) grid.rect() x <- unit(1, "in") y <- unit(1, "in") grid.circle(x, y, r=unit(2, "mm")) loc <- deviceLoc(x, y) loc upViewport() grid.circle(loc$x, loc$y, r=unit(1, "mm"), gp=gpar(fill="black")) ## Something even less obvious grid.newpage() pushViewport(viewport(width=.5, height=.5, angle=30)) grid.rect() x <- unit(.2, "npc") y <- unit(2, "in") grid.circle(x, y, r=unit(2, "mm")) loc <- deviceLoc(x, y) loc upViewport() grid.circle(loc$x, loc$y, r=unit(1, "mm"), gp=gpar(fill="black")) # }