Boxed geom_text with ggplot2

Question

I am developing a graphic with ggplot2 wherein I need to superimpose text over other graphical elements. Depending on the color of the elements underlying the text, it can b

Answer 1

Update for ggplot2 1.0.1

GeomText2 <- proto(ggplot2:::GeomText, {
  objname <- "text2"

  draw <- function(., data, scales, coordinates, ..., parse = FALSE, na.rm = FALSE
                    ,hjust = 0.5, vjust = 0.5
                    ,expand = c(1.1,1.2), bgcol = "black", bgfill = "white", bgalpha = 1) {
    data <- remove_missing(data, na.rm, c("x", "y", "label"), name = "geom_text")

    lab <- data$label
    if (parse) {
      lab <- parse(text = lab)
    }

    with(coord_transform(coordinates, data, scales),{
        sizes <- llply(1:nrow(data),
            function(i) with(data[i, ], {
                grobs <- textGrob(lab[i], default.units="native", rot=angle, gp=gpar(fontsize=size * .pt))
                list(w = grobWidth(grobs), h = grobHeight(grobs))
            })
        )
        w <- do.call(unit.c, lapply(sizes, "[[", "w"))
        h <- do.call(unit.c, lapply(sizes, "[[", "h"))
        gList(rectGrob(x, y,
                     width = w * expand[1], 
                     height = h * expand[length(expand)],
                     just = c(hjust,vjust),
                     gp = gpar(col = alpha(bgcol, bgalpha), fill = alpha(bgfill, bgalpha))),
            .super$draw(., data, scales, coordinates, ..., parse))
    })
  }
})

geom_text2 <- function (mapping = NULL, data = NULL, stat = "identity", position = "identity",parse = FALSE, ...) {
  GeomText2$new(mapping = mapping, data = data, stat = stat, position = position, parse = parse, ...)
}