Outlines appearing but some bugs to fix

I'm using a geom_point with shape 21 (a ring) to do the borders. They're
rendering, but there are problems:
1) outline sizes aren't calculated properly, so they don't stay on the flag
   edges.
2) colours are totally messed up, and it seems like they stick if i draw a new
   plot with modified data. i'm guessing a scope problem (local vars that don't
   get wiped properly)?
3) flags spill out of the plotting area in the rstudio render and in ggsave. they
   don't in svg export, though. this doesn't seem like desirable behaviour, as the
   geom_point outline clips properly in all circumstances.

NAMESPACE

@@ -3,9 +3,14 @@
 S3method(makeContent,flag)
 export(geom_flag)
 export(scale_country)
+importFrom(ggplot2,.pt)
+importFrom(ggplot2,.stroke)
 importFrom(grImport2,pictureGrob)
 importFrom(grid,gList)
 importFrom(grid,gTree)
+importFrom(grid,gpar)
+importFrom(grid,grobTree)
 importFrom(grid,makeContent)
+importFrom(grid,pointsGrob)
 importFrom(grid,setChildren)
 importFrom(grid,unit)

R/geom_flag.R

@@ -1,19 +1,45 @@
 
-flagGrob <- function(x, y, country, size=1, alpha=1){
+flagGrob <- function(x, y, country, size=1, alpha=1, stroke = 0, colour = 'black'){
   # grob(x=x, y=y, country=country, size=size, cl = "flag")
-  gTree(x = x, y = y, country = country, size = size, cl = "flag")
+  gTree(x = x, y = y, country = country, size = size, stroke = stroke,
+    colour = colour, cl = "flag")
 }
 
 #' @export
 makeContent.flag <- function(x) {
   flag_pics <- lapply(seq_along(x$country),
     function(ii) {
-      grImport2::pictureGrob(
-        picture = .flaglist[[x$country[[ii]]]],
-        x = x$x[ii], y = x$y[ii],
-        width = x$size[ii] * unit(1, "mm"),
-        height = x$size[ii] * unit(1, "mm"),
-        distort = FALSE)
+      if (x$stroke[ii] > 0)
+      {
+        grobTree(
+          grImport2::pictureGrob(
+            picture = .flaglist[[x$country[[ii]]]],
+            x = x$x[ii], y = x$y[ii],
+            width = x$size[ii] * unit(1, "mm"),
+            height = x$size[ii] * unit(1, "mm"),
+            distort = FALSE),
+          pointsGrob(
+            x = x$x[ii], y = x$y[ii], pch = 21,
+            gp = gpar(
+              fill = 0, col = x$colour[ii],
+              fontsize =
+                (x$size[ii] * .pt) + (x$stroke[ii] * .stroke),
+              lwd = x$stroke[ii] * .stroke / 2
+            )
+          )
+        )
+      } else if (x$stroke[ii] == 0)
+      {
+        grImport2::pictureGrob(
+          picture = .flaglist[[x$country[[ii]]]],
+          x = x$x[ii], y = x$y[ii],
+          width = x$size[ii] * unit(1, "mm"),
+          height = x$size[ii] * unit(1, "mm"),
+          distort = FALSE)
+      } else
+      {
+        stop('ggflags: stroke must be positive or zero.')
+      }
     })
   setChildren(x, do.call(gList, flag_pics))
 }
@@ -28,16 +54,20 @@ scale_country <- function(..., guide = "legend") {
 
 GeomFlag <- ggproto("GeomFlag", Geom,
                     required_aes = c("x", "y", "country"),
-                    default_aes = aes(size = 5, country="nz"),
+                    default_aes = aes(size = 5, country = "nz", stroke = 0,
+                      colour = "black"),
 
                     draw_key = function (data, params, size) 
                     {
-                      flagGrob(0.5,0.5, country=data$country,  size=data$size)
+                      flagGrob(0.5,0.5, country=data$country,  size=data$size, stroke = data$stroke,
+                               colour = data$colour)
                     },
 
                     draw_group = function(data, panel_scales, coord) {
                       coords <- coord$transform(data, panel_scales)     
-                      flagGrob(coords$x, coords$y, coords$country, coords$size)
+                      flagGrob(x = coords$x, y = coords$y,
+                               country = coords$country, size = coords$size,
+                               stroke = coords$stroke, colour = coords$colour)
                     }
 )
 
@@ -62,8 +92,9 @@ GeomFlag <- ggproto("GeomFlag", Geom,
 #' ggplot(d, aes(x=x, y=y, country=country, size=x)) + 
 #'   geom_flag() + 
 #'   scale_country()
-#' @importFrom grid unit gTree gList makeContent setChildren
+#' @importFrom grid unit gTree gList grobTree makeContent setChildren pointsGrob gpar
 #' @importFrom grImport2 pictureGrob
+#' @importFrom ggplot2 .stroke .pt
 #' @export
 geom_flag <- function(mapping = NULL, data = NULL, stat = "identity",
                       position = "identity", na.rm = FALSE, show.legend = NA,