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

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