allow scale$continuous_limits to overrule expansion limits

Author: teunbrand

R/scale-expansion.R

@@ -146,12 +146,20 @@ expand_limits_scale <- function(scale, expand = expansion(0, 0), limits = waiver
   limits <- limits %|W|% scale$get_limits()
 
   if (scale$is_discrete()) {
+    continuous_limits <- scale$continuous_limits
+    if (is.function(continuous_limits)) {
+      continuous_limits <- continuous_limits(limits)
+    }
+    if (!is.null(continuous_limits)) {
+      continuous_limits <- range(continuous_limits)
+      check_numeric(continuous_limits, call = scale$call, arg = "continuous.limits")
+    }
     coord_limits <- coord_limits %||% c(NA_real_, NA_real_)
     expand_limits_discrete(
-      scale$map(limits),
+      continuous_limits %||% scale$map(limits),
       expand,
       coord_limits,
-      range_continuous = scale$range_c$range
+      range_continuous = continuous_limits %||% scale$range_c$range
     )
   } else {
     # using the inverse transform to resolve the NA value is needed for date/datetime/time