Use justify_grobs for tag justification

Author: thomasp85

R/plot-build.r

@@ -283,11 +283,10 @@ ggplot_gtable.ggplot_built <- function(data) {
   if (tag_pos == "manual") {
     xpos <- theme$plot.tag.position[1]
     ypos <- theme$plot.tag.position[2]
-    tag_parent  <- gTree(
-      children = gList(tag),
-      vp = viewport(x = xpos, y = ypos, width = tag_width, height = tag_height,
-                    just = c(theme$plot.tag$hjust, theme$plot.tag$vjust))
-    )
+    tag_parent <- justify_grobs(tag, x = xpos, y = ypos,
+                                hjust = theme$plot.tag$hjust,
+                                vjust = theme$plot.tag$vjust,
+                                debug = theme$plot.tag$debug)
     plot_table <- gtable_add_grob(plot_table, tag_parent, name = "tag", t = 1,
                                   b = nrow(plot_table), l = 1,
                                   r = ncol(plot_table), clip = "off")