add as.gtable methods (#6372)

Author: teunbrand

DESCRIPTION

@@ -35,7 +35,7 @@ Imports:
     cli,
     grDevices,
     grid,
-    gtable (>= 0.1.1),
+    gtable (>= 0.3.6),
     isoband,
     lifecycle (> 1.0.1),
     rlang (>= 1.1.0),

NAMESPACE

@@ -13,6 +13,8 @@ S3method("[[",ggproto)
 S3method("[[<-",uneval)
 S3method(.DollarNames,ggproto)
 S3method(as.data.frame,mapped_discrete)
+S3method(as.gtable,ggplot)
+S3method(as.gtable,ggplot_built)
 S3method(as.list,ggproto)
 S3method(autolayer,default)
 S3method(autoplot,default)

R/plot-build.R

@@ -312,6 +312,12 @@ ggplotGrob <- function(x) {
   ggplot_gtable(ggplot_build(x))
 }
 
+#' @export
+as.gtable.ggplot <- function(x, ...) ggplotGrob(x)
+
+#' @export
+as.gtable.ggplot_built <- function(x, ...) ggplot_gtable(x)
+
 # Apply function to layer and matching data
 by_layer <- function(f, layers, data, step = NULL) {
   ordinal <- label_ordinal()