transparent theme (#5018)

* theme_transparent

* update unit tests

* document

* new snapshot

* transparent fills -> element_blank()

* move new theme

* adapt theme

* update tests

* move news bullet

* redocument

* cleanup duplicated news entry

---------

Co-authored-by: Teun van den Brand <[email protected]>

NAMESPACE

@@ -721,6 +721,7 @@ export(theme_minimal)
 export(theme_replace)
 export(theme_set)
 export(theme_test)
+export(theme_transparent)
 export(theme_update)
 export(theme_void)
 export(transform_position)

NEWS.md

@@ -212,6 +212,7 @@
 * `stat_summary_bin()` no longer ignores `width` parameter (@teunbrand, #4647).
 * Added `keep.zeroes` argument to `stat_bin()` (@teunbrand, #3449)
 * `coord_sf()` no longer errors when dealing with empty graticules (@teunbrand, #6052)
+* Added `theme_transparent()` with transparent backgrounds (@topepo).
 
 # ggplot2 3.5.1
 

R/theme-defaults.R

@@ -497,6 +497,41 @@ theme_classic <- function(base_size = 11, base_family = "",
     )
 }
 
+#' @export
+#' @rdname ggtheme
+theme_transparent <- function(base_size = 11, base_family = "",
+                              header_family = NULL,
+                              base_line_size = base_size / 22,
+                              base_rect_size = base_size / 22,
+                              ink = "black", paper = alpha(ink, 0)) {
+  force(ink)
+  # Based on theme_bw
+  theme_grey(
+    base_size = base_size,
+    base_family = base_family,
+    header_family = header_family,
+    base_line_size = base_line_size,
+    base_rect_size = base_rect_size,
+    ink = ink, paper = paper
+  ) %+replace%
+    theme(
+      panel.background  = element_blank(),
+      plot.background   = element_blank(),
+      legend.background = element_blank(),
+      legend.key        = element_blank(),
+      # theme_bw specifications
+      panel.border      = element_rect(fill = NA, colour = col_mix(ink, paper, 0.20)),
+      # make gridlines dark, same contrast with white as in theme_grey
+      panel.grid        = element_line(colour = col_mix(ink, paper, 0.92)),
+      # contour strips to match panel contour
+      strip.background  = element_rect(
+        fill = col_mix(ink, paper, 0.85),
+        colour = col_mix(ink, paper, 0.20),
+      ),
+      complete = TRUE
+    )
+}
+
 #' @export
 #' @rdname ggtheme
 theme_void <- function(base_size = 11, base_family = "",

tests/testthat/_snaps/prohibited-functions.md

@@ -219,6 +219,10 @@
       [1] "base_size"      "base_family"    "header_family"  "base_line_size"
       [5] "base_rect_size"
       
+      $theme_transparent
+      [1] "base_size"      "base_family"    "header_family"  "base_line_size"
+      [5] "base_rect_size"
+      
       $theme_void
       [1] "base_size"      "base_family"    "header_family"  "base_line_size"
       [5] "base_rect_size"