positions communicate their aesthetics

Author: teunbrand

R/layer.R

@@ -134,12 +134,12 @@ layer <- function(geom = NULL, stat = NULL,
 
   # Split up params between aesthetics, geom, and stat
   params <- rename_aes(params)
-  aes_params  <- params[intersect(names(params), geom$aesthetics())]
+  aes_params  <- params[intersect(names(params), union(geom$aesthetics(), position$aesthetics()))]
   geom_params <- params[intersect(names(params), geom$parameters(TRUE))]
   stat_params <- params[intersect(names(params), stat$parameters(TRUE))]
 
   ignore <- c("key_glyph", "name")
-  all <- c(geom$parameters(TRUE), stat$parameters(TRUE), geom$aesthetics(), ignore)
+  all <- c(geom$parameters(TRUE), stat$parameters(TRUE), geom$aesthetics(), position$aesthetics(), ignore)
 
   # Take care of plain patterns provided as aesthetic
   pattern <- vapply(aes_params, is_pattern, logical(1))
@@ -170,7 +170,7 @@ layer <- function(geom = NULL, stat = NULL,
 
   extra_aes <- setdiff(
     mapped_aesthetics(mapping),
-    c(geom$aesthetics(), stat$aesthetics())
+    c(geom$aesthetics(), stat$aesthetics(), position$aesthetics())
   )
   # Take care of size->linewidth aes renaming
   if (geom$rename_size && "size" %in% extra_aes && !"linewidth" %in% mapped_aesthetics(mapping)) {

R/position-.R

@@ -68,6 +68,14 @@ Position <- ggproto("Position",
 
   compute_panel = function(self, data, params, scales) {
     cli::cli_abort("Not implemented.")
+  },
+
+  aesthetics = function(self) {
+    required_aes <- self$required_aes
+    if (!is.null(required_aes)) {
+      required_aes <- unlist(strsplit(self$required_aes, "|", fixed = TRUE))
+    }
+    c(union(required_aes, names(self$default_aes)))
   }
 )