ensure expand is also obeyed by scale_thickness_shared

NEWS.md

@@ -1,5 +1,11 @@
 # ggdist (development version)
 
+New features and enhancements:
+
+* To complement the `subguide`s for `geom_slab()`, there are now `subscale`s,
+  which can be used to adjust the `limits` or the `expand` parameter of the 
+  `thickness` per-geometry sub-scales (in much the same way those 
+  parameters can be set on `scale_thickness_shared()`) (#219).
 * Allow use of square `shape`s in `geom_blur_dots()`.
 
 

R/scale_thickness.R

@@ -96,6 +96,7 @@ scale_thickness_shared = function(
   renormalize = FALSE,
   oob = scales::oob_keep,
   guide = "none",
+  expand = c(0, 0),
   ...
 ) {
   sc = continuous_scale(
@@ -104,7 +105,7 @@ scale_thickness_shared = function(
     limits = limits,
     oob = oob,
     guide = guide,
-    expand = expansion(0, 0),
+    expand = expand,
     ...,
     super = ScaleThicknessShared
   )
@@ -115,7 +116,7 @@ scale_thickness_shared = function(
 ScaleThicknessShared = ggproto("ScaleThicknessShared", ScaleContinuous,
   renormalize = FALSE,
 
-  map = function(self, x, limits = self$get_limits()) {
+  map = function(self, x, limits = self$dimension(expand = self$expand)) {
     out = if (is_thickness(x)) {
       x
     } else {

tests/testthat/test.scale_thickness.R

@@ -44,6 +44,14 @@ test_that("infinite thickness is squished", {
   expect_equal(slab_grob$y, unit(c(0, 0.9, 0, 0, 0, 0), "native"))
 })
 
+test_that("expand works", {
+  p = ggplot() +
+    geom_slab(aes(x = 1:2, thickness = 1:2)) +
+    scale_thickness_shared(expand = expansion(c(0,0.25)))
+
+  expect_equal(layer_data(p)$thickness, thickness(1:2 / 2.5, 0, 2.5))
+})
+
 
 # scale_type --------------------------------------------------------------