Negative tick strips (#5258)

* Test for presence/absence instead of size

* Add test

Author: teunbrand

R/facet-grid-.R

@@ -367,14 +367,10 @@ FacetGrid <- ggproto("FacetGrid", Facet,
       theme$panel.spacing.y %||% theme$panel.spacing)
 
     # Add axes
-    axis_height_top <- max_height(axes$x$top)
-    axis_height_bottom <- max_height(axes$x$bottom)
-    axis_width_left <- max_width(axes$y$left)
-    axis_width_right <- max_width(axes$y$right)
-    panel_table <- gtable_add_rows(panel_table, axis_height_top, 0)
-    panel_table <- gtable_add_rows(panel_table, axis_height_bottom, -1)
-    panel_table <- gtable_add_cols(panel_table, axis_width_left, 0)
-    panel_table <- gtable_add_cols(panel_table, axis_width_right, -1)
+    panel_table <- gtable_add_rows(panel_table, max_height(axes$x$top),     0)
+    panel_table <- gtable_add_rows(panel_table, max_height(axes$x$bottom), -1)
+    panel_table <- gtable_add_cols(panel_table, max_width(axes$y$left),     0)
+    panel_table <- gtable_add_cols(panel_table, max_width(axes$y$right),   -1)
     panel_pos_col <- panel_cols(panel_table)
     panel_pos_rows <- panel_rows(panel_table)
 
@@ -392,7 +388,7 @@ FacetGrid <- ggproto("FacetGrid", Facet,
     panel_pos_col <- panel_cols(panel_table)
     if (switch_x) {
       if (!is.null(strips$x$bottom)) {
-        if (inside_x || as.numeric(axis_height_bottom) == 0) {
+        if (inside_x || all(vapply(axes$x$bottom, is.zero, logical(1)))) {
           panel_table <- gtable_add_rows(panel_table, max_height(strips$x$bottom), -2)
           panel_table <- gtable_add_grob(panel_table, strips$x$bottom, -2, panel_pos_col$l, clip = "on", name = paste0("strip-b-", seq_along(strips$x$bottom)), z = 2)
         } else {
@@ -403,7 +399,7 @@ FacetGrid <- ggproto("FacetGrid", Facet,
       }
     } else {
       if (!is.null(strips$x$top)) {
-        if (inside_x || as.numeric(axis_height_top) == 0) {
+        if (inside_x || all(vapply(axes$x$top, is.zero, logical(1)))) {
           panel_table <- gtable_add_rows(panel_table, max_height(strips$x$top), 1)
           panel_table <- gtable_add_grob(panel_table, strips$x$top, 2, panel_pos_col$l, clip = "on", name = paste0("strip-t-", seq_along(strips$x$top)), z = 2)
         } else {
@@ -416,7 +412,7 @@ FacetGrid <- ggproto("FacetGrid", Facet,
     panel_pos_rows <- panel_rows(panel_table)
     if (switch_y) {
       if (!is.null(strips$y$left)) {
-        if (inside_y || as.numeric(axis_width_left) == 0) {
+        if (inside_y || all(vapply(axes$y$left, is.zero, logical(1)))) {
           panel_table <- gtable_add_cols(panel_table, max_width(strips$y$left), 1)
           panel_table <- gtable_add_grob(panel_table, strips$y$left, panel_pos_rows$t, 2, clip = "on", name = paste0("strip-l-", seq_along(strips$y$left)), z = 2)
         } else {
@@ -427,7 +423,7 @@ FacetGrid <- ggproto("FacetGrid", Facet,
       }
     } else {
       if (!is.null(strips$y$right)) {
-        if (inside_y || as.numeric(axis_width_right) == 0) {
+        if (inside_y || all(vapply(axes$y$right, is.zero, logical(1)))) {
           panel_table <- gtable_add_cols(panel_table, max_width(strips$y$right), -2)
           panel_table <- gtable_add_grob(panel_table, strips$y$right, panel_pos_rows$t, -2, clip = "on", name = paste0("strip-r-", seq_along(strips$y$right)), z = 2)
         } else {

tests/testthat/test-facet-strips.R

@@ -159,6 +159,14 @@ test_that("padding is only added if axis is present", {
   pg <- ggplotGrob(p + scale_x_continuous(position = "top"))
   expect_equal(length(pg$heights), 14)
   expect_equal(as.character(pg$heights[7]), "1cm")
+
+  # Also add padding with negative ticks and no text (#5251)
+  pg <- ggplotGrob(
+    p + scale_x_continuous(labels = NULL, position = "top") +
+      theme(axis.ticks.length.x.top = unit(-2, "mm"))
+  )
+  expect_equal(length(pg$heights), 14)
+  expect_equal(as.character(pg$heights[7]), "1cm")
 })
 
 test_that("y strip labels are rotated when strips are switched", {