[R] lattice grob

[baptiste auguie]

Dear list,

I'm trying to arrange various grid objects on a page using a
frameGrob. It works fine with basic grobs (textGrob, gTree, etc.), and
also with ggplot2 objects using the ggplotGrob() function. I am
however stuck with lattice. As far as I understand, lattice produces a
list of class trellis, which is eventually displayed using the
plot.trellis method. I am not sure if/how one can convert this list
into a high-level grob. I tried the following,

latticeGrob <- function(p, ...){
  grob(p=p, ..., cl="lattice")
}

drawDetails.lattice <- function(x, recording=FALSE){
  lattice:::plot.trellis(x$p)
}

p1 <- xyplot(1:10 ~ 1:10)
g1 <- latticeGrob(p1)

grid.draw(g1) # works fine

but,

fg <- frameGrob(layout = grid.layout(1,1))
fg <- placeGrob(fg, g1, row = 1, col = 1)
grid.draw(fg)

Error in UseMethod("depth") :
  no applicable method for 'depth' applied to an object of class "NULL"

Ideas are most welcome,

Best regards,

baptiste

> sessionInfo()
R version 2.10.1 RC (2009-12-06 r50690)
i386-apple-darwin9.8.0

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/C/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] grid      tools     stats     graphics  grDevices utils
datasets  methods   base

other attached packages:
[1] ggplot2_0.8.7   digest_0.4.1    reshape_0.8.3   plyr_0.1.9
proto_0.3-8     gridExtra_0.5   lattice_0.17-26 gtools_2.6.1