Various fixes to themes (tidyverse#1679)

* Match default font size to new default

Set in theme_grey to 11

* Match theme_bw with theme_grey better

Keep contrast and size of gridlines (in particular, previously the minor
grid lines were thicker than the major ones which looked weird)

Remove the border around the legend key which complicates things visually
for little gain

Outline panel and facet strips with a dark-ish grey

* Simplify theme_linedraw

Use strip.text instead and strip.text.x and strip.text.y separately

Slightly thicker grid lines compared to the previous iteration (but still
quite thin)

Base on theme_bw rather than on theme_grey

* Improve and homogenise theme_dark and theme_light

Use strip.text instead and strip.text.x and strip.text.y separately

As in theme_grey and theme_bw, keep the same color for major and minor
gridlines; just change the thickness (as was already done before).

In theme_dark, make the strips the inverse of what they are in theme_grey

* Reorder elements in the specification of theme_minimal

Just to match theme_grey. No visual change beyond the changes to theme_bw
on which this is based

* Fix regressions in theme_classic

Explicitly add axes which disappeared due to new specifications in
theme_bw at some point.

Increase size of the borders of strips to match axes visually.

* Keep legend title in theme_void

(otherwise the plot may be un-understandable)

* Improve comments and reorder elements to match other theme specification

* Fix alignment of code in all theme functions

* Add NEWs bullet for theme update

* Move theme_dark next to theme_light in the code

They are related and their examples are in this order

Author: jiho

NEWS.md

@@ -1,5 +1,9 @@
+
 # ggplot2 2.1.0.9000 
 
+* Themes are more homogeneous visually, and match `theme_grey` better.
+  (@jiho, #1679)
+
 * `position_stack()` and `position_fill()` now sorts the stacking order so it 
   matches the order of the grouping. Use level reordering to alter the stacking 
   order. The default legend and stacking order is now also in line. The default 

R/theme-defaults.r

@@ -150,142 +150,145 @@ theme_gray <- theme_grey
 
 #' @export
 #' @rdname ggtheme
-theme_bw <- function(base_size = 12, base_family = "") {
+theme_bw <- function(base_size = 11, base_family = "") {
   # Starts with theme_grey and then modify some parts
   theme_grey(base_size = base_size, base_family = base_family) %+replace%
     theme(
-      axis.text         = element_text(size = rel(0.8)),
-      axis.ticks        = element_line(colour = "black"),
-      legend.key        = element_rect(colour = "grey80"),
-      panel.background  = element_rect(fill = "white", colour = NA),
-      panel.border      = element_rect(fill = NA, colour = "grey50"),
-      panel.grid.major  = element_line(colour = "grey90", size = 0.2),
-      panel.grid.minor  = element_line(colour = "grey98", size = 0.5),
-      strip.background  = element_rect(fill = "grey80", colour = "grey50", size = 0.2)
+      # white background and dark border
+      panel.background = element_rect(fill = "white", colour = NA),
+      panel.border     = element_rect(fill = NA, colour = "grey20"),
+      # make gridlines dark, same contrast with white as in theme_grey
+      panel.grid.major = element_line(colour = "grey92"),
+      panel.grid.minor = element_line(colour = "grey92", size = 0.25),
+      # contour strips to match panel contour
+      strip.background = element_rect(fill = "grey85", colour = "grey20"),
+      # match legend key to background
+      legend.key       = element_rect(fill = "white", colour=NA)
     )
 }
 
 #' @export
 #' @rdname ggtheme
-theme_linedraw <- function(base_size = 12, base_family = "") {
-  half_line <- base_size / 2
+theme_linedraw <- function(base_size = 11, base_family = "") {
+  # Starts with theme_bw and then modify some parts
+  # = replace all greys with pure black or white
+  theme_bw(base_size = base_size, base_family = base_family) %+replace%
+    theme(
+      # black text and ticks on the axes
+      axis.text        = element_text(colour = "black", size = rel(0.8)),
+      axis.ticks       = element_line(colour = "black", size = 0.25),
+      # NB: match the *visual* thickness of axis ticks to the panel border
+      #     0.5 clipped looks like 0.25
+      
+      # pure black panel border and grid lines, but thinner
+      panel.border     = element_rect(fill = NA, colour = "black", size = 0.5),
+      panel.grid.major = element_line(colour = "black", size = 0.05),
+      panel.grid.minor = element_line(colour = "black", size = 0.025),
+      
+      # strips with black background and white text
+      strip.background = element_rect(fill = "black"),
+      strip.text       = element_text(colour = "white", size = rel(0.8))
+    )
+}
+
+#' @export
+#' @rdname ggtheme
+theme_light <- function(base_size = 11, base_family = "") {
   # Starts with theme_grey and then modify some parts
   theme_grey(base_size = base_size, base_family = base_family) %+replace%
     theme(
-      axis.text         = element_text(colour = "black", size = rel(0.8)),
-      axis.ticks        = element_line(colour = "black", size = 0.25),
-      legend.key        = element_rect(colour = "black", size = 0.25),
-      panel.background  = element_rect(fill = "white", colour = NA),
-      panel.border      = element_rect(fill = NA, colour = "black", size = 0.5),
-      panel.grid.major  = element_line(colour = "black", size = 0.05),
-      panel.grid.minor  = element_line(colour = "black", size = 0.01),
-      strip.background  = element_rect(fill = "black", colour = NA),
-      strip.text.x      = element_text(
-                            colour = "white",
-                            margin = margin(t = half_line, b = half_line)
-                          ),
-      strip.text.y      = element_text(
-                            colour = "white",
-                            angle = 90,
-                            margin = margin(l = half_line, r = half_line)
-                          )
+      # white panel with light grey border
+      panel.background = element_rect(fill = "white", colour = NA),
+      panel.border     = element_rect(fill = NA, colour = "grey70", size = 0.5),
+      # light grey, thinner gridlines
+      # => make them slightly darker to keep acceptable contrast
+      panel.grid.major = element_line(colour = "grey87", size = 0.25),
+      panel.grid.minor = element_line(colour = "grey87", size = 0.125),
+
+      # match axes ticks thickness to gridlines and colour to panel border
+      axis.ticks       = element_line(colour = "grey70", size = 0.25),
+
+      # match legend key to panel.background
+      legend.key       = element_rect(fill = "white", colour = NA),
+      
+      # dark strips with light text (inverse contrast compared to theme_grey)
+      strip.background = element_rect(fill = "grey70", colour = NA),
+      strip.text       = element_text(colour = "white", size = rel(0.8))
     )
+
 }
 
 #' @export
 #' @rdname ggtheme
-theme_light <- function(base_size = 12, base_family = "") {
-  half_line <- base_size / 2
+theme_dark <- function(base_size = 11, base_family = "") {
   # Starts with theme_grey and then modify some parts
   theme_grey(base_size = base_size, base_family = base_family) %+replace%
     theme(
-      axis.ticks        = element_line(colour = "grey70", size = 0.25),
-      legend.key        = element_rect(fill = "white", colour = "grey50", size = 0.25),
-      panel.background  = element_rect(fill = "white", colour = NA),
-      panel.border      = element_rect(fill = NA, colour = "grey70", size = 0.5),
-      panel.grid.major  = element_line(colour = "grey85", size = 0.25),
-      panel.grid.minor  = element_line(colour = "grey93", size = 0.125),
-      strip.background  = element_rect(fill = "grey70", colour = NA),
-      strip.text.x      = element_text(
-        colour = "white",
-        margin = margin(t = half_line, b = half_line)
-      ),
-      strip.text.y      = element_text(
-        colour = "white",
-        angle = -90,
-        margin = margin(l = half_line, r = half_line)
-      )
-    )
+      # dark panel
+      panel.background = element_rect(fill = "grey50", colour = NA),
+      # inverse grid lines contrast compared to theme_grey
+      # make them thinner and try to keep the same visual contrast as in theme_light
+      panel.grid.major = element_line(colour = "grey42", size = 0.25),
+      panel.grid.minor = element_line(colour = "grey42", size = 0.125),
+
+      # match axes ticks thickness to gridlines
+      axis.ticks       = element_line(colour = "grey20", size = 0.25),
+      
+      # match legend key to panel.background
+      legend.key       = element_rect(fill = "grey50", colour = NA),
 
+      # dark strips with light text (inverse contrast compared to theme_grey)
+      strip.background = element_rect(fill = "grey15", colour = NA),
+      strip.text       = element_text(colour = "grey90", size = rel(0.8))
+    )
 }
 
 #' @export
 #' @rdname ggtheme
-theme_minimal <- function(base_size = 12, base_family = "") {
-  # Starts with theme_bw and then modify some parts
+theme_minimal <- function(base_size = 11, base_family = "") {
+  # Starts with theme_bw and remove most parts
   theme_bw(base_size = base_size, base_family = base_family) %+replace%
     theme(
+      axis.ticks.x      = element_blank(),
+      axis.ticks.y      = element_blank(),
       legend.background = element_blank(),
       legend.key        = element_blank(),
       panel.background  = element_blank(),
       panel.border      = element_blank(),
       strip.background  = element_blank(),
-      plot.background   = element_blank(),
-      axis.ticks        = element_line(),
-      axis.ticks.x      = element_blank(),
-      axis.ticks.y      = element_blank(),
-      axis.ticks.length = unit(1, "lines")
+      plot.background   = element_blank()
     )
 }
 
 #' @export
 #' @rdname ggtheme
-theme_classic <- function(base_size = 12, base_family = ""){
+theme_classic <- function(base_size = 11, base_family = ""){
   theme_bw(base_size = base_size, base_family = base_family) %+replace%
     theme(
+      # no background and no grid
       panel.border     = element_blank(),
-      axis.line        = element_line(colour = "black"),
-      panel.grid.major   = element_line(),
-      panel.grid.major.x = element_blank(),
-      panel.grid.major.y = element_blank(),
-      panel.grid.minor   = element_line(),
-      panel.grid.minor.x = element_blank(),
-      panel.grid.minor.y = element_blank(),
-      strip.background = element_rect(colour = "black", size = 0.5),
-      legend.key       = element_blank()
-    )
-}
+      panel.grid.major = element_blank(),
+      panel.grid.minor = element_blank(),
 
-#' @export
-#' @rdname ggtheme
-theme_dark <- function(base_size = 12, base_family = "") {
-  half_line <- base_size / 2
-  # Starts with theme_grey and then modify some parts
-  theme_grey(base_size = base_size, base_family = base_family) %+replace%
-    theme(
-      axis.ticks        = element_line(colour = "grey40", size = 0.25),
-      legend.key        = element_rect(fill = "grey50", colour = "grey40", size = 0.25),
-      panel.background  = element_rect(fill = "grey50", colour = NA),
-      panel.grid.major  = element_line(colour = "grey40", size = 0.25),
-      panel.grid.minor  = element_line(colour = "grey45", size = 0.125),
-      strip.background  = element_rect(fill = "grey20", colour = NA),
-      strip.text.x      = element_text(
-        colour = "white",
-        margin = margin(t = half_line, b = half_line)
-      ),
-      strip.text.y      = element_text(
-        colour = "white",
-        angle = -90,
-        margin = margin(l = half_line, r = half_line)
-      )
+      # show axes
+      axis.line.x      = element_line(colour = "black", size = 0.5),
+      axis.line.y      = element_line(colour = "black", size = 0.5),
+
+      # match legend key to panel.background
+      legend.key       = element_blank(),
+
+      # simple, black and white strips
+      strip.background = element_rect(fill = "white", colour = "black", size = 1)
+      # NB: size is 1 but clipped, it looks like the 0.5 of the axes
     )
 }
 
 #' @export
 #' @rdname ggtheme
-theme_void <- function(base_size = 12, base_family = "") {
+theme_void <- function(base_size = 11, base_family = "") {
   theme(
-    # Use only inherited elements and make everything blank
+    # Use only inherited elements and make almost everything blank
+    # Only keep indispensable text
     line =               element_blank(),
     rect =               element_blank(),
     text =               element_text(
@@ -294,14 +297,14 @@ theme_void <- function(base_size = 12, base_family = "") {
                             lineheight = 0.9, hjust = 0.5, vjust = 0.5, angle = 0,
                             margin = margin(), debug = FALSE
                          ),
-    plot.margin =        unit(c(0, 0, 0, 0), "lines"),
     axis.text.x =        element_blank(),
     axis.text.y =        element_blank(),
     axis.title.x =       element_blank(),
     axis.title.y =       element_blank(),
     legend.text =        element_text(size = rel(0.8)),
-    legend.title =       element_blank(),
+    legend.title =       element_text(hjust = 0),
     strip.text =         element_text(size = rel(0.8)),
+    plot.margin =        unit(c(0, 0, 0, 0), "lines"),
 
     complete = TRUE
   )