Fill closed arrows in element_line() (#2924)

Author: yutannihilation

NEWS.md

@@ -9,6 +9,8 @@
 * Aesthetic mappings now accept functions that return `NULL` (@yutannihilation,
   #2997)
 
+* Closed arrows in `element_line()` are now filled (@yutannihilation, #2924).
+
 # ggplot2 3.1.0
 
 ## Breaking changes

R/theme-elements.r

@@ -226,9 +226,15 @@ element_grob.element_line <- function(element, x = 0:1, y = 0:1,
   default.units = "npc", id.lengths = NULL, ...) {
 
   # The gp settings can override element_gp
-  gp <- gpar(lwd = len0_null(size * .pt), col = colour, lty = linetype, lineend = lineend)
-  element_gp <- gpar(lwd = len0_null(element$size * .pt), col = element$colour,
-    lty = element$linetype, lineend = element$lineend)
+  gp <- gpar(
+    col = colour, fill = colour,
+    lwd = len0_null(size * .pt), lty = linetype, lineend = lineend
+  )
+  element_gp <- gpar(
+    col = element$colour, fill = element$colour,
+    lwd = len0_null(element$size * .pt), lty = element$linetype,
+    lineend = element$lineend
+  )
   arrow <- if (is.logical(element$arrow) && !element$arrow) {
     NULL
   } else {