geom custom

geom_custom.r

library(proto)
library(grid)

geom_custom <- function (mapping = NULL, data = NULL, stat = "identity",
                         position = "identity", show_guide = FALSE, ...) { 
  GeomCustom$new(mapping = mapping, data = data, stat = stat,
                 position = position, show_guide = show_guide, ...)
}

GeomCustom <- proto(ggplot2:::Geom, {
  
  objname <- "custom"
 
  new <- function(., data = NULL, mapping = NULL, grob =NULL, ...) {
    .super$new(., data = data, mapping = mapping, grob=grob, inherit.aes = FALSE, ...)
  }
  
 draw <- function(., data, scales, coordinates, grob, just=c("centre", "centre"), ...) {
   with(coord_transform(coordinates, data, scales), {
       width <- grobWidth(grob)
       height <- grobHeight(grob)
       grob <- editGrob(grob, vp=viewport(x = x, y = y,
                          width=width, height=height, just = just), ...)
       ggname(.$my_name(), grob)
  })
}
  
  default_aes <- function(.) 
	aes(x=0.5, y=0.5)
  default_stat <- function(.) StatIdentity

})


library(gridExtra)
g <- tableGrob(head(iris[1:3,]))

d <- qplot(1,1, geom="blank")
d + annotate("custom", x=1, y=1, grob=g)