Incorrect Font Spacing in Plot Viewer Preview

[sebsepp]

Hi everyone,

this is my first time starting a discussion on GitHub - if there is anything I can improve in how I report issues, please let me know :)

I’m encountering a rendering issue in the plot viewer when embedding custom fonts using the showtext package. For example, in the screenshot below, you can see how the axis ticks and axis labels overlap (especially on the x-axis):

However, when I execute the same code in RStudio, the plot renders correctly and the spacing is fine — which leads me to believe this is not an issue with showtext itself:

Additional context:
Since the rendering worked fine previously, I initially suspected that XQuartz (which I had recently installed for another project) might be causing the issue. However, uninstalling it had no effect.
Also, when saving the figure using ggsave(), the output looks correct — so the problem seems limited to the preview in the plot viewer. However, without a reliable preview, adjusting text and font sizes becomes a bit tedious.

Currently I'm using:

• R 4.5.0
• Positron 2025.05.0 (Universal) build 142
• M3 MacBook Air with macOS Sequoia 15.5

Here is the example code I used:

library(tidyverse)
library(showtext)

font_add_google("Roboto Condensed", "roboto")
showtext_opts(dpi = 400)
showtext_auto()

ggplot(mtcars, aes(mpg, wt)) +
  geom_point() +
  labs(
    x = "Miles per gallon",
    y = "Weight"
  ) +
  theme(text = element_text(family = "roboto", size = 12))

Thanks in advance for any ideas or suggestions,
Sebastian

[DavisVaughan]

@thomasp85 it looks like this might be a ragg issue?

With ragg

With options(ark.ragg = FALSE)

# Restart R and run this as your first command for it to work
# options(ark.ragg = FALSE)

library(tidyverse)
library(showtext)

font_add_google("Roboto Condensed", "roboto")
showtext_opts(dpi = 400)
showtext_auto()

ggplot(mtcars, aes(mpg, wt)) +
  geom_point() +
  labs(
    x = "Miles per gallon",
    y = "Weight"
  ) +
  theme(text = element_text(family = "roboto", size = 12))

[sebsepp]

thanks for your suggestion, this did the trick for me!

[thomasp85]

showtext works by hacking into the graphics device, hijacking it's text rendering routines and inserting it's own. So any issue with showtext is it's own fault, not that of the graphics device, unless you can show that the device has issues without showtext.

There is no upside to using showtext here - ragg has access to all fonts on the system and systemfonts provide easy download and installation from google fonts and other repositories. If you really want to use showtext then you can switch to the default graphics device as Davis has shown

[sebsepp]

thank you, that helped me to understand the problem!

[thomasp85]

No problem - if you want to dive (much) deeper into the topic I've recently written about it https://www.tidyverse.org/blog/2025/05/fonts-in-r/ at length

I have no issue with people using showtext, but because it works in the way it does then any issue with it must fall back on itself. However, as a user you are seldom aware of those intricacies and it is much more natural to think the graphics device is at fault

[thomasp85]

My guess at what's going on is that showtext correctly hijacks the shadow device, resulting in correct spacing calculations, but doesn't correctly hijacks the playback device giving the discrepancy we observe. When not using ragg these two are the same devices (png()), but when using ragg they are different (agg_record() and agg_png())

[DavisVaughan]

That's helpful context, thanks. And honestly that's convincing enough to me that we should not try and worry about supporting that case, especially since systemfonts exists.