More aggressively enforce device capabilities

R/geom-ribbon.R

@@ -141,6 +141,9 @@ GeomRibbon <- ggproto("GeomRibbon", Geom,
  )
  non_constant <- names(aes)[lengths(aes) > 1]
  if (coord$is_linear()) {
+ if (any(c("fill", "alpha") %in% non_constant)) {
+ check_device("gradients", action = "abort", maybe = TRUE)
+ }
  # For linear coords, we can make a fill/alpha gradient, so we allow
  # these to vary
  non_constant <- setdiff(non_constant, c("fill", "alpha"))
@@ -150,8 +153,7 @@ GeomRibbon <- ggproto("GeomRibbon", Geom,
  "Aesthetics can not vary along a ribbon: {.and {.field {non_constant}}}."
  )
  }
- if (length(aes$fill) > 1 || length(aes$alpha) > 1) {
- check_device("gradients")
+ if ((length(aes$fill) > 1 || length(aes$alpha) > 1)) {
  transformed <- coord$transform(flip_data(data, flipped_aes), panel_params)
  if (flipped_aes) {
  keep <- is.finite(tranformed$y)

tests/testthat/test-geom-ribbon.R

@@ -76,6 +76,10 @@ test_that("outline.type option works", {
 })
 
 test_that("ribbons can have gradients", {
+ skip_if_not(
+ check_device("gradients", action = "test"),
+ "graphics device does not support gradients."
+ )
 
  df <- data.frame(x = 1:2, ymin = c(-1:-2), ymax = 1:2)
  p <- ggplot(df, aes(x, ymin = ymin, ymax = ymax, fill = x)) +