ggsave() produces aliased png files on Windows

[thomas-neitmann]

When using ggsave() to save a plot as png on Windows the resulting image is quite aliased (zoom in to see the ragged line).

library(ggplot2)
data(gapminder, package = "gapminder")
china <- gapminder[gapminder$country == "China", ]

ggplot(china, aes(year, lifeExp)) + geom_line()
ggsave("test.png")

This is a known issue of the png() graphics device on Windows. To mitigate this one has to use cairo and set the antialias argument like so.

ggsave("test2.png", type = "cairo-png", antialias = "subpixel")

This is easy enough if you know this trick. I'd suggest to automatically set type = 'cairo-png' and antialias = 'subpixel' on Windows if these arguments have not been explicitly set. I've recently implemented something along those line in the {hexSticker} package which uses ggsave(). Have a look here.

I'd be happy to create a pull request.

[yutannihilation]

Thanks. I agree to change the default, but we tend to recommend ragg package for high quality plots.

[thomasp85]

I'm closing this for now, since we need to have a broader discussion about whether to force certain devices (ragg) on the user