Minor fixes to keep compatibility with ggtern (#2913)

* fixes to keep compatibility with ggtern

* allow CRAN ggtern to work with geom_sf()

Author: clauswilke

R/ggplot-global.R

@@ -13,16 +13,22 @@ ggplot_global$theme_current <- list()
 ggplot_global$element_tree <- list()
 
 # List of all aesthetics known to ggplot
-ggplot_global$all_aesthetics <- c(
+# (In the future, .all_aesthetics should be removed in favor
+# of direct assignment to ggplot_global$all_aesthetics, see below.)
+.all_aesthetics <- c(
   "adj", "alpha", "angle", "bg", "cex", "col", "color",
   "colour", "fg", "fill", "group", "hjust", "label", "linetype", "lower",
   "lty", "lwd", "max", "middle", "min", "pch", "radius", "sample", "shape",
   "size", "srt", "upper", "vjust", "weight", "width", "x", "xend", "xmax",
   "xmin", "xintercept", "y", "yend", "ymax", "ymin", "yintercept", "z"
 )
 
+ggplot_global$all_aesthetics <- .all_aesthetics
+
 # Aesthetic aliases
-ggplot_global$base_to_ggplot <- c(
+# (In the future, .base_to_ggplot should be removed in favor
+# of direct assignment to ggplot_global$base_to_ggplot, see below.)
+.base_to_ggplot <- c(
   "col"   = "colour",
   "color" = "colour",
   "pch"   = "shape",
@@ -36,3 +42,5 @@ ggplot_global$base_to_ggplot <- c(
   "min"   = "ymin",
   "max"   = "ymax"
 )
+
+ggplot_global$base_to_ggplot <- .base_to_ggplot

R/sf.R

@@ -199,7 +199,7 @@ default_aesthetics <- function(type) {
   }
 }
 
-sf_grob <- function(row, lineend, linejoin, linemitre) {
+sf_grob <- function(row, lineend = "butt", linejoin = "round", linemitre = 10) {
   # Need to extract geometry out of corresponding list column
   geometry <- row$geometry[[1]]
 

R/theme-elements.r

@@ -256,8 +256,9 @@ el_def <- function(class = NULL, inherit = NULL, description = NULL) {
 
 
 # This data structure represents the theme elements and the inheritance
-# among them.
-ggplot_global$element_tree <- list(
+# among them. (In the future, .element_tree should be removed in favor
+# of direct assignment to ggplot_global$element_tree, see below.)
+.element_tree <- list(
   line                = el_def("element_line"),
   rect                = el_def("element_rect"),
   text                = el_def("element_text"),
@@ -352,6 +353,7 @@ ggplot_global$element_tree <- list(
   aspect.ratio        = el_def("character")
 )
 
+ggplot_global$element_tree <- .element_tree
 
 # Check that an element object has the proper class
 #