Resolution of geom_tile() per panel (#5764)

* compute resolution per panel

* add news bullet

* add test

Author: teunbrand

NEWS.md

@@ -42,7 +42,9 @@
 * `theme()` gets new `spacing` and `margins` arguments that all other spacings
   and (non-text) margins inherit from (@teunbrand, #5622).
 * `geom_ribbon()` can have varying `fill` or `alpha` in linear coordinate
-  systems (@teunbrand, #4690)
+  systems (@teunbrand, #4690).
+* `geom_tile()` computes default widths and heights per panel instead of
+  per layer (@teunbrand, #5740).
 
 # ggplot2 3.5.1
 

R/geom-tile.R

@@ -109,8 +109,11 @@ GeomTile <- ggproto("GeomTile", GeomRect,
   extra_params = c("na.rm"),
 
   setup_data = function(data, params) {
-    data$width <- data$width %||% params$width %||% resolution(data$x, FALSE, TRUE)
-    data$height <- data$height %||% params$height %||% resolution(data$y, FALSE, TRUE)
+    
+    data$width <- data$width %||% params$width %||%
+      stats::ave(data$x, data$PANEL, FUN = function(x) resolution(x, FALSE, TRUE))
+    data$height <- data$height %||% params$height %||%
+      stats::ave(data$y, data$PANEL, FUN = function(y) resolution(y, FALSE, TRUE))
 
     transform(data,
       xmin = x - width / 2,  xmax = x + width / 2,  width = NULL,

tests/testthat/test-geom-tile.R

@@ -34,3 +34,18 @@ test_that("accepts linejoin parameter", {
   gp2 <- layer_grob(ggplot(df, aes(x, y)) + geom_tile(linejoin = "round"))[[1]]$gp
   expect_equal(gp2$linejoin, "round")
 })
+
+test_that("width and height are inferred per panel", {
+  df <- data_frame0(
+    x = c(1, 2, 3, 10, 20, 30),
+    y = c(10, 10.5, 11, 100, 200, 300),
+    f = rep(c("A", "B"), each = 3)
+  )
+
+  ld <- layer_data(
+    ggplot(df, aes(x, y)) + geom_tile() + facet_wrap(~f, scales = "free")
+  )
+
+  expect_equal(ld$xmax - ld$xmin, c(1, 1, 1, 10, 10, 10))
+  expect_equal(ld$ymax - ld$ymin, c(0.5, 0.5, 0.5, 100, 100, 100))
+})