Svglite device and custom fonts inside knitr

[Darxor]

Using custom fonts with svglite device (with {systemfonts}, rather than loading them via {extrafont}) leads to issues:

• Charts throw warnings like:

Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, : font family 'Montserrat' not found in PostScript font database

• Some text manipulations, like those done by ggtext::geom_richtext produce unexpected results.

Example

In my example I used Montserrat font (can be installed as system font from google fonts).

An .rmd like one bellow will produce warnings as one above and text in the chart will be rendered incorrectly.

---
title: "svglite reprex"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(
  echo = TRUE,
  dev = "svglite",
  fig.height = 4L,
  fig.width = 8L
)
```

## Example 
Systemfonts successfully finds the font.
```{r font_exists}
systemfonts::match_font("Montserrat")
```

```{r chart}
library(ggplot2)
chart_data <- data.frame(
  x = -2L:2L,
  y = -2L:2L,
  label = "example text here"
)
ggplot(chart_data, aes(x, y)) +
  ggtext::geom_richtext(
    aes(label = label),
    size = 3L,
    family = "Montserrat"
  )
```

Produced chart:

Note: this chart will be absolutely fine when rendered with svglite directly.

Proposed solution

The issue is caused by using a pdf device at the time of calling evaluate() in eng_r(), if chunk device was set to svglite.
A change to chunk_device() to support svglite device seems to fix this and produces a report with no warnings and no visual issues. I will provide a PR for this.

Issue is reproducible to me under macOS and Ubuntu

Session info

r$> xfun::session_info('knitr')
R version 4.3.1 (2023-06-16)
Platform: aarch64-apple-darwin20 (64-bit)
Running under: macOS Ventura 13.4.1, RStudio 0


Locale: en_US.UTF-8 / en_US.UTF-8 / en_US.UTF-8 / C / en_US.UTF-8 / en_US.UTF-8

time zone: Europe/Moscow
tzcode source: internal

Package version:
  evaluate_0.21   graphics_4.3.1  grDevices_4.3.1 highr_0.10      knitr_1.43      methods_4.3.1   stats_4.3.1     tools_4.3.1     utils_4.3.1     xfun_0.39       yaml_2.3.7 

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