export_graph results in Pango warning when using an installed non-standard font

[benjamin-chan]

I'm getting the following warning message with the export_graph() function:

(process:8876): Pango-WARNING **: 19:08:04.072: couldn't load font "Arial Narrow Not-Rotated 10", falling back to "Sans Not-Rotated 10", expect ugly output.

The desired result is a PNG (or any other file) with the Arial Narrow font.

Specifically, I'm trying to use Arial Narrow, which was installed using the extrafont package. The installation is confirmed looking at the fonttable() output. I've also tried using a different font also installed with extrafont and get the same Pango warning.

Strangely, render_graph() produces the desired result on-screen. But I want to export to a PNG file.

Details below:

library(magrittr)
library(DiagrammeR)

# Confirm presence of Arial Narrow
extrafont::fonttable()$FamilyName %>% grepl("Arial Narrow", .) %>% any()

# Create graph
graph <-
  create_graph() %>%
  add_node(label = "Lorem", node_aes = node_aes(fontname = "Arial Narrow")) %>%
  add_node(label = "Ipsum", node_aes = node_aes(fontname = "Arial Narrow")) %>%
  add_edge(from = 1, to = 2)

# Renders correctly
render_graph(graph)

# Results in Pango warning, regardless of file type
# (process:8876): Pango-WARNING **: 19:08:04.072: couldn't load font "Arial Narrow Not-Rotated 10", falling back to "Sans Not-Rotated 10", expect ugly output.
export_graph(graph, file_name = "test.png", width = 600)
export_graph(graph, file_name = "test.pdf", width = 600)
export_graph(graph, file_name = "test.svg", width = 600)
export_graph(graph, file_name = "test.ps", width = 600)

Session info below

R version 4.4.0 (2024-04-24 ucrt)
Platform: x86_64-w64-mingw32/x64
Running under: Windows 10 x64 (build 19045)

Matrix products: default


locale:
[1] LC_COLLATE=English_United States.utf8
[2] LC_CTYPE=English_United States.utf8
[3] LC_MONETARY=English_United States.utf8
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.utf8

time zone: America/Los_Angeles
tzcode source: internal

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

other attached packages:
[1] DiagrammeR_1.0.11 magrittr_2.0.3

loaded via a namespace (and not attached):
 [1] jsonlite_1.8.8     dplyr_1.1.4        compiler_4.4.0     tidyselect_1.2.1
 [5] Rcpp_1.0.12        stringr_1.5.1      rsvg_2.6.0         yaml_2.3.8        
 [9] fastmap_1.1.1      R6_2.5.1           generics_0.1.3     curl_5.2.1
[13] htmlwidgets_1.6.4  visNetwork_2.1.2   tibble_3.2.1       pillar_1.9.0
[17] RColorBrewer_1.1-3 rlang_1.1.3        utf8_1.2.4         V8_4.4.2
[21] Rttf2pt1_1.3.12    stringi_1.8.3      DiagrammeRsvg_0.1  cli_3.6.2
[25] withr_3.0.0        digest_0.6.35      rstudioapi_0.16.0  lifecycle_1.0.4
[29] vctrs_0.6.5        extrafont_0.19     glue_1.7.0         extrafontdb_1.0   
[33] fansi_1.0.6        purrr_1.0.2        tools_4.4.0        pkgconfig_2.0.3
[37] htmltools_0.5.8.1