using showtext leads to smaller font size in ggplot2

[ThierryO]

Reproducible example.

library(ggplot2)
ggplot(mtcars, aes(x = mpg, y = disp)) + geom_point() + ggtitle("standard")

library(ggplot2)
showtext::showtext_auto()
ggplot(mtcars, aes(x = mpg, y = disp)) + geom_point() +
  ggtitle("showtext, no font")

sessioninfo::session_info()
─ Session info ────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 setting  value                       
 version  R version 4.1.0 (2021-05-18)
 os       Ubuntu 18.04.5 LTS          
 system   x86_64, linux-gnu           
 ui       RStudio                     
 language nl_BE:nl                    
 collate  nl_BE.UTF-8                 
 ctype    nl_BE.UTF-8                 
 tz       Europe/Brussels             
 date     2021-07-02                  

─ Packages ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 package     * version date       lib source        
 assertthat    0.2.1   2019-03-21 [1] CRAN (R 4.1.0)
 cli           2.5.0   2021-04-26 [1] CRAN (R 4.1.0)
 colorspace    2.0-1   2021-05-04 [1] CRAN (R 4.1.0)
 crayon        1.4.1   2021-02-08 [1] CRAN (R 4.1.0)
 DBI           1.1.1   2021-01-15 [1] CRAN (R 4.1.0)
 digest        0.6.27  2020-10-24 [1] CRAN (R 4.1.0)
 dplyr         1.0.6   2021-05-05 [1] CRAN (R 4.1.0)
 ellipsis      0.3.2   2021-04-29 [1] CRAN (R 4.1.0)
 fansi         0.5.0   2021-05-25 [1] CRAN (R 4.1.0)
 farver        2.1.0   2021-02-28 [1] CRAN (R 4.1.0)
 fortunes      1.5-4   2016-12-29 [1] CRAN (R 4.1.0)
 generics      0.1.0   2020-10-31 [1] CRAN (R 4.1.0)
 ggplot2     * 3.3.3   2020-12-30 [1] CRAN (R 4.1.0)
 glue          1.4.2   2020-08-27 [1] CRAN (R 4.1.0)
 gtable        0.3.0   2019-03-25 [1] CRAN (R 4.1.0)
 labeling      0.4.2   2020-10-20 [1] CRAN (R 4.1.0)
 lifecycle     1.0.0   2021-02-15 [1] CRAN (R 4.1.0)
 magrittr      2.0.1   2020-11-17 [1] CRAN (R 4.1.0)
 munsell       0.5.0   2018-06-12 [1] CRAN (R 4.1.0)
 pillar        1.6.1   2021-05-16 [1] CRAN (R 4.1.0)
 pkgconfig     2.0.3   2019-09-22 [1] CRAN (R 4.1.0)
 purrr         0.3.4   2020-04-17 [1] CRAN (R 4.1.0)
 R6            2.5.0   2020-10-28 [1] CRAN (R 4.1.0)
 rlang         0.4.11  2021-04-30 [1] CRAN (R 4.1.0)
 rstudioapi    0.13    2020-11-12 [1] CRAN (R 4.1.0)
 scales        1.1.1   2020-05-11 [1] CRAN (R 4.1.0)
 sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 4.1.0)
 showtext      0.9-2   2021-01-10 [1] CRAN (R 4.1.0)
 showtextdb    3.0     2020-06-04 [1] CRAN (R 4.1.0)
 sysfonts      0.8.3   2021-01-10 [1] CRAN (R 4.1.0)
 tibble        3.1.2   2021-05-16 [1] CRAN (R 4.1.0)
 tidyselect    1.1.1   2021-04-30 [1] CRAN (R 4.1.0)
 utf8          1.2.1   2021-03-12 [1] CRAN (R 4.1.0)
 vctrs         0.3.8   2021-04-29 [1] CRAN (R 4.1.0)
 withr         2.4.2   2021-04-18 [1] CRAN (R 4.1.0)

[yixuan]

You may need to set showtext_opts(dpi = ...) using the resolution of your device.

[ThierryO]

Passing the dpi of the current chunk works. Although not very user friendly as I'm using showtext in a custom ggplot2 theme package (https://github.com/inbo/INBOtheme/blob/2a41272624e9092d24f0e92772bfebeef12c695c/R/theme_inbo2015.R#L54).

showtext::showtext_opts(dpi = opts_chunk$get()$dpi)
ggplot(mtcars, aes(x = mpg, y = disp)) + geom_point() +
  ggtitle(paste("showtext, knitr dpi", opts_chunk$get()$dpi))

[tomicapretto]

I'm experiencing the same problem. I just entered to the repo to report the same issue.

My code

good

library(ggplot2)
library(ggstatsplot)
library(palmerpenguins)
penguins <- tidyr::drop_na(penguins)

plt <- ggbetweenstats(
  data = penguins,
  x = species,
  y = bill_length_mm,
  title = "Distribution of bill length across penguins species",
  xlab = "Penguins Species",
  ylab = "Bill Length"
)

ggsave("plot_good.png", plt, width = 8, height = 8)

bad

library(ggplot2)
library(ggstatsplot)
library(palmerpenguins)
library(showtext)
showtext_auto()

penguins <- tidyr::drop_na(penguins)

plt <- ggbetweenstats(
  data = penguins,
  x = species,
  y = bill_length_mm,
  title = "Distribution of bill length across penguins species",
  xlab = "Penguins Species",
  ylab = "Bill Length"
)

ggsave("plot_bad.png", plt, width = 8, height = 8)

[yixuan]

@ThierryO @tomicapretto When using showtext inside R markdown, do not explicitly call showtext_auto(). Instead, use the knitr option fig.showtext=TRUE, which will correctly set the dpi parameter. See the short example here.

On the other hand, if you use showtext in pure R code, always set dpi according to your device parameter. For example, ggsave has a default value of 300 for dpi.

[tomicapretto]

Thanks so much for the answer @yixuan!

[ThierryO]

I don't know whether the end user will use my code (custom ggplot2 theme) in a plain R script or an Rmd. What would you recommend to keep it user friendly?

[yixuan]

@ThierryO I haven't tried this myself, but probably you can take a look at the thematic package, which also uses showtext and supports theming.

I guess you can always call showtext_auto() inside your code, but users who run Rmd need to add fig.showtext = TRUE in their own documents.

[SchmidtPaul]

Hi, I made a reprex just for completeness as this had been confusing me for quite some time. Thanks for your answer @yixuan!

library(cowplot)
library(ggplot2)
library(pdftools)
library(png)
library(showtext)

p <- ggplot(data = PlantGrowth,
             aes(y = weight, x = group)) +
  geom_point() +
  labs(title = "This is the title",
       subtitle = "Here is also a subtitle",
       caption = "And here is a caption")

# Standard - not involving {showtext} -------------------------------------
ggsave("p1.png", p)
#> Saving 7 x 5 in image
ggsave("p1.pdf", p)
#> Saving 7 x 5 in image

png1 <- readPNG("p1.png")
pdf1 <- pdf_render_page("p1.pdf", page = 1, dpi = 300)

plot_grid(ggdraw() + draw_image(png1) + draw_label("png"),
          ggdraw() + draw_image(pdf1) + draw_label("pdf"))

✔️ This works fine ✔️

# showtext::showtext_auto() -----------------------------------------------
showtext::showtext_auto()

ggsave("p2.png", p)
#> Saving 7 x 5 in image
ggsave("p2.pdf", p)
#> Saving 7 x 5 in image

png2 <- readPNG("p2.png")
pdf2 <- pdf_render_page("p2.pdf", page = 1, dpi = 300)

plot_grid(ggdraw() + draw_image(png2) + draw_label("png"),
          ggdraw() + draw_image(pdf2) + draw_label("pdf"))

❌ This does not work ❌

# showtext::showtext_auto() & showtext_opts(dpi = 300) --------------------
showtext::showtext_auto()
showtext_opts(dpi = 300)

ggsave("p3.png", p)
#> Saving 7 x 5 in image
ggsave("p3.pdf", p)
#> Saving 7 x 5 in image

png3 <- readPNG("p3.png")
pdf3 <- pdf_render_page("p3.pdf", page = 1, dpi = 300)

plot_grid(ggdraw() + draw_image(png3) + draw_label("png"),
          ggdraw() + draw_image(pdf3) + draw_label("pdf"))

✔️ This works fine ✔️

^{Created on 2022-07-29 by the reprex package (v2.0.1)}