ggsave does not respect ggplot2::unit in width and height arguments, defaults to inches

[hlynurhallgrims]

I believe I've found a problem with the ggsave function. When denoting width and height using the unit function imported from the grid package. ggsave accepts the arguments without problem but actually takes the numeric value to mean inches, instead of the unit denoted.

Using the units = argument fixes this, so perhaps the only changes are warnings and changing the documentation. Let me know if you agree, and I could file a PR if needed.

Here is the code to reproduce the bug:

library(ggplot2)

ggplot(mpg, aes(x = cty, y = hwy)) +
  geom_point()

ggsave("test.png", 
       width = unit(297, "mm"), 
       height = unit(210, "mm"))
#> Error in `ggsave()`:
#> ! Dimensions exceed 50 inches (`height` and `width` are specified in
#>   inches not pixels).
#> ℹ If you're sure you want a plot that big, use `limitsize = FALSE`.
#> Backtrace:
#>     ▆
#>  1. └─ggplot2::ggsave("test.png", width = unit(297, "mm"), height = unit(210, "mm"))
#>  2.   └─ggplot2:::plot_dim(...)
#>  3.     └─cli::cli_abort(...)
#>  4.       └─rlang::abort(...)

^{Created on 2023-06-29 with reprex v2.0.2}

[teunbrand]

Thanks for spotting this. Yeah I'd agree that the documentation is a little bit on the ambiguous side; half-suggesting to use grid::unit() whereas one shouldn't. Throwing an error when is.unit(width) || is.unit(height) would be informative I think. A PR would we welcome!