Rework legend spacing

NEWS.md

@@ -1,5 +1,11 @@
 # ggplot2 (development version)
 
+* The spacing between legend keys and their labels, in addition to legends
+  and their titles, is now controlled by the text's `margin` setting. Not
+  specifying margins will automatically add appropriate text margins. This
+  leaves the `legend.spacing` dedicated to controlling the spacing between
+  different keys (#5455).
+
 * New function `check_device()` for testing the availability of advanced 
   graphics features introduced in R 4.1.0 onwards (@teunbrand, #5332).
 

R/guide-colorbar.R

@@ -429,17 +429,10 @@ GuideColourbar <- ggproto(
       return(list(labels = zeroGrob()))
     }
 
-    just <- if (params$direction == "horizontal") {
-      elements$text$vjust
-    } else {
-      elements$text$hjust
-    }
-
     list(labels = flip_element_grob(
       elements$text,
       label = validate_labels(key$.label),
       x = unit(key$.value, "npc"),
-      y = rep(just, nrow(key)),
       margin_x = FALSE,
       margin_y = TRUE,
       flip = params$direction == "vertical"

R/guide-legend.R

@@ -437,6 +437,17 @@ GuideLegend <- ggproto(
       "cm", valueOnly = TRUE
     )
 
+    if (is.null(params$label.theme$margin %||% theme$legend.text$margin) &&
+        !inherits(elements$text, "element_blank")) {
+      i <- match(params$label.position, .trbl[c(3, 4, 1, 2)])
+      elements$text$margin[i] <- elements$text$margin[i] + gap
+    }
+    if (is.null(params$title.theme$margin %||% theme$legend.title$margin) &&
+        !inherits(elements$title, "element_blank")) {
+      i <- match(params$title.position, .trbl[c(3, 4, 1, 2)])
+      elements$title$margin[i] <- elements$title$margin[i] + gap
+    }
+
     # Evaluate backgrounds early
     if (!is.null(elements$background)) {
       elements$background <- ggname(
@@ -521,17 +532,17 @@ GuideLegend <- ggproto(
     hgap <- elements$hgap %||% 0
     widths <- switch(
       params$label.position,
-      "left"   = list(label_widths, hgap, widths, hgap),
-      "right"  = list(widths, hgap, label_widths, hgap),
+      "left"   = list(label_widths, widths, hgap),
+      "right"  = list(widths, label_widths, hgap),
       list(pmax(label_widths, widths), hgap * (!byrow))
     )
     widths  <- head(vec_interleave(!!!widths),  -1)
 
     vgap <- elements$vgap %||% 0
     heights <- switch(
       params$label.position,
-      "top"    = list(label_heights, vgap, heights, vgap),
-      "bottom" = list(heights, vgap, label_heights, vgap),
+      "top"    = list(label_heights, heights, vgap),
+      "bottom" = list(heights, label_heights, vgap),
       list(pmax(label_heights, heights), vgap * (byrow))
     )
     heights <- head(vec_interleave(!!!heights), -1)
@@ -543,14 +554,14 @@ GuideLegend <- ggproto(
     # Combine title with rest of the sizes based on its position
     widths <- switch(
       params$title.position,
-      "left"  = c(title_width, hgap, widths),
-      "right" = c(widths, hgap, title_width),
+      "left"  = c(title_width, widths),
+      "right" = c(widths, title_width),
       c(widths, max(0, title_width - sum(widths)))
     )
     heights <- switch(
       params$title.position,
-      "top"    = c(title_height, vgap, heights),
-      "bottom" = c(heights, vgap, title_height),
+      "top"    = c(title_height, heights),
+      "bottom" = c(heights, title_height),
       c(heights, max(0, title_height - sum(heights)))
     )
 
@@ -585,29 +596,29 @@ GuideLegend <- ggproto(
     switch(
       params$label.position,
       "top" = {
-        key_row   <- key_row   * 2
-        label_row <- label_row * 2 - 2
+        key_row   <- key_row + df$R
+        label_row <- key_row - 1
       },
       "bottom" = {
-        key_row   <- key_row   * 2 - 2
-        label_row <- label_row * 2
+        key_row   <- key_row + df$R - 1
+        label_row <- key_row + 1
       },
       "left" = {
-        key_col   <- key_col   * 2
-        label_col <- label_col * 2 - 2
+        key_col   <- key_col + df$C
+        label_col <- key_col - 1
       },
       "right" = {
-        key_col   <- key_col   * 2 - 2
-        label_col <- label_col * 2
+        key_col   <- key_col + df$C - 1
+        label_col <- key_col + 1
       }
     )
 
     # Offset layout based on title position
     switch(
       params$title.position,
       "top" = {
-        key_row   <- key_row   + 2
-        label_row <- label_row + 2
+        key_row   <- key_row   + 1
+        label_row <- label_row + 1
         title_row <- 2
         title_col <- seq_along(sizes$widths) + 1
       },
@@ -616,8 +627,8 @@ GuideLegend <- ggproto(
         title_col <- seq_along(sizes$widths) + 1
       },
       "left" = {
-        key_col   <- key_col   + 2
-        label_col <- label_col + 2
+        key_col   <- key_col   + 1
+        label_col <- label_col + 1
         title_row <- seq_along(sizes$heights) + 1
         title_col <- 2
       },

tests/testthat/test-guides.R

@@ -601,10 +601,10 @@ test_that("guides title and text are positioned correctly", {
       scale_fill_continuous(name = "the\ncontinuous\ncolorscale")
   )
   expect_doppelganger("vertical gap of 1cm between guide title and guide",
-    p + theme(legend.spacing.y = grid::unit(1, "cm"))
+    p + theme(legend.title = element_text(margin = margin(b = 1, unit = "cm")))
   )
   expect_doppelganger("horizontal gap of 1cm between guide and guide text",
-    p + theme(legend.spacing.x = grid::unit(1, "cm"))
+    p + theme(legend.text = element_text(margin = margin(l = 1, unit = "cm")))
   )
 
   # now test label positioning, alignment, etc
@@ -619,8 +619,8 @@ test_that("guides title and text are positioned correctly", {
 
   expect_doppelganger("guide title and text positioning and alignment via themes",
     p + theme(
-      legend.title = element_text(hjust = 0.5, margin = margin(t = 30)),
-      legend.text = element_text(hjust = 1, margin = margin(l = 5, t = 10, b = 10))
+      legend.title = element_text(hjust = 0.5, margin = margin(t = 30, b = 5.5)),
+      legend.text = element_text(hjust = 1, margin = margin(l = 10.5, t = 10, b = 10))
     )
   )