geom_textsf randomly throws erros when specification of font family is missing (OpenSUSE Leap 15.5, R 4.3.2)

[klausbraun]

Allan,

I was really happy when I discovered your library, in my case especially when I saw the examples with geom_textsf and geom_labelsf (https://allancameron.github.io/geomtextpath/). When I try to execute the code:

library(geomtextpath)
library(sf)

df <- data.frame(x = c(-4.2518, -3.1883), 
                 y = c(55.8642, 55.9533),
                 label = c("Glasgow", "Edinburgh"))

p <- ggplot(data = df) +
  geom_textsf(data = waterways,
              aes(label = name), text_smoothing = 65, linecolour = "#8888B3", 
              color = "gray30", vjust = -0.8, fill = "#E6F0B3", 
              alpha = 0.8, fontface = 3, size = 3) + 
  geom_point(aes(x, y), data = df, color = "gray50", size = 3) + 
  geom_textpath(aes(x, y, label = label), color = "gray50",
                hjust = c(-0.2, 1.2)) +
  theme(panel.grid = element_line()) + 
  lims(x = c(-4.7, -3), y = c(55.62, 56.25))

and print p I get the following weird behavior:

> p
Error in `geom_textsf()`:
! Problem while converting geom to grob.
ℹ Error occurred in the 1st layer.
Caused by error in `get_glyph_info_c()`:
! 'Rf_translateCharUTF8' must be called on a CHARSXP, but got 'bytecode'
Run `rlang::last_trace()` to see where the error occurred.
> p
Error in `geom_textsf()`:
! Problem while converting geom to grob.
ℹ Error occurred in the 1st layer.
Caused by error:
! Failed to load `` from font (繀) with freetype error -1
Run `rlang::last_trace()` to see where the error occurred.
> p

where the the plot p is printed after two failed tries. The backtrace gives:

 21. │                     └─geomtextpath (local) draw_panel(...)
 22. │                       └─geomtextpath:::sf_textgrob(...)
 23. │                         ├─grid::addGrob(...)
 24. │                         ├─sf::st_as_grob(...)
 25. │                         └─geomtextpath:::st_as_grob.sfc_labelled(...)
 26. │                           └─geomtextpath::textpathGrob(...)
 27. │                             └─geomtextpath:::measure_label(...)
 28. │                               └─geomtextpath (local) measure(...)
 29. │                                 └─geomtextpath:::translate_glyph(txt$index, txt$substring, gp)
 30. │                                   └─base::lapply(gp$fontfamily %nz% "fallback", glyph_index)
 31. │                                     └─geomtextpath (local) FUN(X[[i]], ...)
 32. │                                       └─systemfonts::glyph_info(idx, family = name)
 33. │                                         └─systemfonts:::get_glyph_info_c(...)

Also the example sometimes fails completely and R is aborted.

The solution I found after a while is to explicitly tell geom_textsf and geom_textpath the font family which should be used, i.e. something like:

   ...
  geom_textsf(data = waterways,
              aes(label = name), text_smoothing = 65, linecolour = "#8888B3", 
              color = "gray30", vjust = -0.8, fill = "#E6F0B3", family = "Times New Roman",
              alpha = 0.8, fontface = 3, size = 3) + 
   ...

I'm working on OpenSUSE Leap 15.5 which actual R 4.3.2 and packages sf_1.0-15, geomtextpath_0.1.1, and ggplot2_3.4.4.

Using the workaround described above I am able to use this great package, but I think it would be good to either solve the problem (when it is a problem of geomtextpath), or to give some hints according to the workaround - unless I am the only one facing this behavior.

Best

Klaus

[teunbrand]

Does using systemfonts::glyph_info("A") give you a similar error? If so, systemfonts might not be able to automatically detect fonts, or determine the default font, with your OS.

[klausbraun]

No, this works fine:

> 
> systemfonts::glyph_info("A")
  glyph index width height x_bearing y_bearing x_advance y_advance       bbox
1     A    38     8      9         0         9         8         0 0, 8, 0, 9
>