[R] draw.key; getting grobWidth to respect fontfamily="mono"

[Paul Murrell]

Hi

On 07/09/12 09:35, Benjamin Tyner wrote:
> Update: seems one way to skin this cat is to add
>
>    gp = gpar(fontfamily="mono")
>
> to the viewport() call itself. If anyone has any suggestions for a
> robust way to extract this piece information from the key grob itself
> (it's nested several levels deep), I'm all ears.

I'm going to try to blame 'lattice' for this problem (because it appears 
to be generating "strwidth" units for the text entries in the key rather 
than "grobwidth" units [so the 'gp' settings on the text grobs are being 
ignored when widths are calculated]).  (Though 'lattice' is probably 
doing that to avoid using packGrob() and being further slowed down by 
'grid'!)

However, since you are already deep enough into 'grid' to be using 
viewports and grobWidth() yourself, I suspect that you could get what 
you want by avoiding draw.key() altogether.  You could generate a text 
grob yourself (based on your 'GOFlist'), directly query it for its 
width, build a viewport based on that width (similar to the viewport 
that you are already creating), push the viewport and draw the grob.
Something like this ...

GOFgrob <- function(x) {
     textGrob(c(x$title, x$text$label),
              x=.5, y=unit(.5, "npc") + unit(1:-1, "lines"),
              gp=gpar(fontfamily=c("sans", "mono", "mono")))
}

plot <- xyplot(actual + forecast ~ yyyymm | cond,
                data = Data,
                layout = c(1,2),
                type = "l",
                panel = function(x,y,GOFlist,...){
                  panel.xyplot(x,y,...)
                  pn <- panel.number()
                  key <- GOFgrob(GOFlist[[pn]])
                  vp <- viewport(x = 1,
                                 y = 1,
                                 width = grobWidth(key) +
                                         unit(2, "lines"),
                                 height = grobHeight(key) +
                                          unit(1, "lines"),
                                 just = c("right","top")
                                 )
                  pushViewport(vp)
                  grid.draw(key)
                  grid.rect()
                  popViewport()
                },
                GOFlist = GOFlist
                )

Hope that helps.

Paul

> Thanks
> Ben
>
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-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/