ggsave(): restore previous device. Fixes #2363

Author: wch

NEWS.md

@@ -253,6 +253,9 @@ up correct aspect ratio, and draws a graticule.
 * `ggsave()`'s DPI argument now supports 3 string options: "retina" (320
   DPI), "print" (300 DPI), and "screen" (72 DPI) (@foo-bar-baz-qux, #2156).
 
+* `ggsave()` now correctly restores the previous graphics device when several
+  graphics devices are open. (#2363)
+
 * `print.ggplot()` now returns the original ggplot object, instead of the 
   output from `ggplot_build()`. Also, the object returned from 
   `ggplot_build()` now has the class `"ggplot_built"`. (#2034)

R/save.r

@@ -53,8 +53,12 @@ ggsave <- function(filename, plot = last_plot(),
   if (!is.null(path)) {
     filename <- file.path(path, filename)
   }
+  old_dev <- dev.cur()
   dev(file = filename, width = dim[1], height = dim[2], ...)
-  on.exit(utils::capture.output(grDevices::dev.off()))
+  on.exit(utils::capture.output({
+    grDevices::dev.off()
+    dev.set(old_dev)
+  }))
   grid.draw(plot)
 
   invisible()

tests/testthat/test-ggsave.R

@@ -11,6 +11,26 @@ test_that("ggsave creates file", {
   expect_true(file.exists(path))
 })
 
+test_that("ggsave restores previous graphics device", {
+  # When multiple devices are open, dev.off() restores the next one in the list,
+  # not the previously-active one. (#2363)
+  path <- tempfile()
+  on.exit(unlink(path))
+
+  png()
+  png()
+  on.exit({
+    dev.off()
+    dev.off()
+  }, add = TRUE)
+
+  old_dev <- dev.cur()
+  p <- ggplot(mpg, aes(displ, hwy)) + geom_point()
+  ggsave(path, p, device = "png", width = 5, height = 5)
+
+  expect_identical(old_dev, dev.cur())
+})
+
 
 # plot_dim ---------------------------------------------------------------