respect show.legend in colorbar (#1782)

Fixes #1568

* Add guide_geom.colorbar method and refactored

Author: thomasp85

NEWS.md

@@ -42,6 +42,8 @@
 * `scale_*_datetime` now has support for timezones. If time data has been 
   encoded with a timezone this will be used, but it can be overridden with the
   `timezone` argument in the scale constructor.
+  
+* `geom_*(show.legend = FALSE)` now works for `guide_colorbar`
 
 * The documentation for theme elements has been improved (#1743).
 

R/guide-colorbar.r

@@ -211,7 +211,22 @@ guide_merge.colorbar <- function(guide, new_guide) {
 
 # this guide is not geom-based.
 #' @export
-guide_geom.colorbar <- function(guide, ...) {
+guide_geom.colorbar <- function(guide, layers, default_mapping) {
+  # Layers that use this guide
+  guide_layers <- plyr::llply(layers, function(layer) {
+    matched <- matched_aes(layer, guide, default_mapping)
+
+    if (length(matched) && ((is.na(layer$show.legend) || layer$show.legend))) {
+      layer
+    } else {
+      # This layer does not use this guide
+      NULL
+    }
+  })
+
+  # Remove this guide if no layer uses it
+  if (length(compact(guide_layers)) == 0) guide <- NULL
+
   guide
 }
 

R/guide-legend.r

@@ -252,11 +252,7 @@ guide_merge.legend <- function(guide, new_guide) {
 guide_geom.legend <- function(guide, layers, default_mapping) {
   # arrange common data for vertical and horizontal guide
   guide$geoms <- plyr::llply(layers, function(layer) {
-    all <- names(c(layer$mapping, if (layer$inherit.aes) default_mapping, layer$stat$default_aes))
-    geom <- c(layer$geom$required_aes, names(layer$geom$default_aes))
-    matched <- intersect(intersect(all, geom), names(guide$key))
-    matched <- setdiff(matched, names(layer$geom_params))
-    matched <- setdiff(matched, names(layer$aes_params))
+    matched <- matched_aes(layer, guide, default_mapping)
 
     if (length(matched) > 0) {
       # This layer contributes to the legend

R/guides-.r

@@ -297,3 +297,12 @@ guide_merge <- function(...) UseMethod("guide_merge")
 guide_geom <- function(...) UseMethod("guide_geom")
 
 guide_gengrob <- function(...) UseMethod("guide_gengrob")
+
+# Helpers
+matched_aes <- function(layer, guide, defaults) {
+  all <- names(c(layer$mapping, if (layer$inherit.aes) defaults, layer$stat$default_aes))
+  geom <- c(layer$geom$required_aes, names(layer$geom$default_aes))
+  matched <- intersect(intersect(all, geom), names(guide$key))
+  matched <- setdiff(matched, names(layer$geom_params))
+  setdiff(matched, names(layer$aes_params))
+}

tests/testthat/test-guides.R

@@ -8,3 +8,12 @@ test_that("colourbar trains without labels", {
   expect_equal(names(out$key), c("colour", ".value"))
 })
 
+test_that("Colorbar respects show.legend in layer", {
+  df <- data.frame(x = 1:3, y = 1)
+  p <- ggplot(df, aes(x = x, y = y, color = x)) +
+    geom_point(size = 20, shape = 21, show.legend = FALSE)
+  expect_false("guide-box" %in% ggplotGrob(p)$layout$name)
+  p <- ggplot(df, aes(x = x, y = y, color = x)) +
+    geom_point(size = 20, shape = 21, show.legend = TRUE)
+  expect_true("guide-box" %in% ggplotGrob(p)$layout$name)
+})