Request: allow user to specify Symbol font

[christyray]

With the release of R 4.0.0, the default x11(), png(), jpeg(), tiff(), bmp(), svg(), cairo_pdf(), and cairo_ps() devices accept a symbolfamily argument to let the user change the font used for symbols in an image (source).

With Base R png():

library(ggplot2)
library(ragg)
library(scales)

greek <- as.data.frame(c("alpha", "beta", "gamma"))
names(greek) <- "greek"

p <- ggplot(greek, aes(x = greek, y = 1)) +
  theme(
    plot.title = element_blank(),
    axis.title = element_blank(),
    axis.ticks = element_blank(),
    axis.text.x = element_text(family = "Fira Sans", size = 16),
    axis.text.y = element_blank()
  ) +
  scale_x_discrete(name = NULL, labels = label_parse())

ggsave(
  "greek_base.png",
  plot = p,
  device = png,
  width = 3, height = 1, dpi = 600,
  type = "cairo", symbolfamily = cairoSymbolFont("Fira Sans")
)

^{Created on 2021-08-27 by the reprex package (v2.0.1)}

This gives this plot, withe the "Fira Sans" font used:

With ragg::agg_png():

library(ggplot2)
library(ragg)
library(scales)

greek <- as.data.frame(c("alpha", "beta", "gamma"))
names(greek) <- "greek"

p <- ggplot(greek, aes(x = greek, y = 1)) +
  theme(
    plot.title = element_blank(),
    axis.title = element_blank(),
    axis.ticks = element_blank(),
    axis.text.x = element_text(family = "Fira Sans", size = 16),
    axis.text.y = element_blank()
  ) +
  scale_x_discrete(name = NULL, labels = label_parse())

ggsave(
  "greek_ragg.png", 
  plot = p, 
  device = ragg::agg_png,
  width = 3, height = 1, dpi = 600
)

^{Created on 2021-08-27 by the reprex package (v2.0.1)}

Which gives this plot, using the system default "Symbol" font:

Session Info

> sessionInfo()
R version 4.1.1 (2021-08-10)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Big Sur 11.5.2

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.1/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] scales_1.1.1  ragg_1.1.3    ggplot2_3.3.5

loaded via a namespace (and not attached):
 [1] highr_0.9         pillar_1.6.2      compiler_4.1.1    tools_4.1.1      
 [5] digest_0.6.27     evaluate_0.14     lifecycle_1.0.0   tibble_3.1.4     
 [9] gtable_0.3.0      pkgconfig_2.0.3   rlang_0.4.11      reprex_2.0.1     
[13] rstudioapi_0.13   cli_3.0.1         DBI_1.1.1         yaml_2.2.1       
[17] xfun_0.25         fastmap_1.1.0     withr_2.4.2       dplyr_1.0.7      
[21] knitr_1.33        fs_1.5.0          generics_0.1.0    vctrs_0.3.8      
[25] systemfonts_1.0.2 grid_4.1.1        tidyselect_1.1.1  glue_1.4.2       
[29] R6_2.5.1          textshaping_0.3.5 processx_3.5.2    fansi_0.5.0      
[33] rmarkdown_2.10    clipr_0.7.1       callr_3.7.0       purrr_0.3.4      
[37] magrittr_2.0.1    ps_1.6.0          ellipsis_0.3.2    htmltools_0.5.2  
[41] assertthat_0.2.1  colorspace_2.0-2  labeling_0.4.2    utf8_1.2.2       
[45] munsell_0.5.0     crayon_1.4.1     

As far as I can tell, there isn't currently a way to specify the font to use for symbols with the ragg package. It would be helpful if there were because the default font does not match stylistically with many sans serif fonts.

[thomasp85]

ragg uses systemfonts to figure out fonts - here you can register substitutes for the system native sans, serif, mono, emoji, and symbol fonts using register_font() (also exported by ragg)...

However, ragg had an bug that prevented this from being honoured with the symbol font - this will be fixed in the next version