add freeze method to viewscales

Author: teunbrand

R/scale-view.R

@@ -150,5 +150,21 @@ ViewScale <- ggproto("ViewScale", NULL,
     }
 
     self$rescale(b)
+  },
+  freeze = function(self) {
+    if (self$scale$is_discrete()) {
+      limits <- self$get_limits()
+    } else {
+      limits <- self$continuous_range
+    }
+    ggproto(
+      NULL, self$scale,
+      breaks = self$get_breaks(),
+      minor_breaks = self$get_breaks_minor(),
+      limits = limits,
+      expand = c(0, 0, 0, 0),
+      continuous_limits = self$continuous_range,
+      train = function (...) NULL
+    )
   }
 )