On Linux the hat from expression(hat(...)) is put in the wrong location

[remlapmot]

I noticed this is happening on the GitHub actions pkgdown.yaml workflows running on ubuntu-latest (and I have reproduced this on a local install of Ubuntu 24.04).

You can see on this plot using agg_png() the hats are put in the wrong place.

library(ragg)
agg_png("ragg-plot.png")
par(mar = c(5, 5, 5, 5), cex.lab = 1.3)
plot(1:10, ylab = expression(hat(beta)), xlab = expression(hat(beta)))
title("Plot saved with ragg_png()")
dev.off()

Whereas using png() they are above the betas as expected.

png("png-plot.png")
par(mar = c(5, 5, 5, 5), cex.lab = 1.3)
plot(1:10, ylab = expression(hat(beta)), xlab = expression(hat(beta)))
title("Plot saved with png()")
dev.off()

Note this doesn't occur on either macOS nor Windows 11.

Tested using ragg version 1.4.0.

Maybe related to #89

[remlapmot]

Apologies, this was in fact another example of #136 - it appears as you correctly identified that a lot of the time on Linux the default symbol font is not a good choice for plotmath under ragg (under grDevices it's fine). Like the poster of that issue, my system reported Standard Symbols PS as first choice for symbols.

> systemfonts::font_info(c("sans", "symbol"))[, 2:9]
  index              family   style italic  bold monospace weight  width
1     0         DejaVu Sans    Book  FALSE FALSE     FALSE normal normal
2     0 Standard Symbols PS Regular  FALSE FALSE     FALSE normal normal

As you suggested, choosing a different symbol font fixed plotmath expressions under ragg. If anyone else hits this I chose Liberation Sans as follows.

systemfonts::register_variant("symbol", "Liberation Sans")

Then the system reports.

> systemfonts::font_info(c("sans", "symbol"))[,2:9]
# A data frame: 2 × 8
  index family          style   italic bold  monospace weight width 
  <int> <chr>           <chr>   <lgl>  <lgl> <lgl>     <ord>  <ord> 
1     0 DejaVu Sans     Book    FALSE  FALSE FALSE     normal normal
2     0 Liberation Sans Regular FALSE  FALSE FALSE     normal normal

And then all my plotmath expressions rendered as expected on Linux.