Rendering pdf images using the cairo_pdf device as default.

[arnaudgallou]

Is there an option to render/save figures as pdf using the cairo_pdf device as default? I've figures generated using ggplot2 with unicode characters or transparent colors in them that don't render well with the default device. I get better results when explicitly saving figures using ggsave with device = cairo_pdf, which is not convenient.

---
format: pdf
fig-format: pdf
execute: 
  echo: false
  warning: false
---

```{r}
library(tidyverse)

(ggplot() +
  geom_segment(aes(x = 0, xend = 1, y = 1, yend = 0)) +
  xlab("\u0394")) %>% 
  ggsave("test.pdf", ., device = cairo_pdf)
```

::: {#fig-a}
![](test.pdf)

This is a figure caption.
:::

I’m running on macOS 12 for information.

[cderv]

I think you would need to use a knitr only solution (meaning not a Quarto configuration working also for other language).

You can change the default device with knitr using the dev chunk option

On the chunk you need

```{r, dev='cairo_pdf'}
#| label: fig-a
#| fig-cap: This is a figure caption.
library(ggplot2)

ggplot() +
  geom_segment(aes(x = 0, xend = 1, y = 1, yend = 0)) +
  xlab("\u0394")
```

Or globally in a setup chunk

```{r setup, include=FALSE}
knitr::opts_chunk$set(dev = "cairo_pdf")
```

or using Quarto specific syntax in YAML for engine (https://quarto.org/docs/computations/execution-options.html#engine-binding)

knitr:
  opts_chunk: 
    dev: cairo_pdf

This way, knitr should use grDevices::cairo_pdf() to save plots produced in chunks.

Hope it helps

[arnaudgallou]

Awesome, exactly what I needed! Thank you.

[grantmcdermott]

Piggy-backing on this question: Is there a way to automatically invoke (or limit) dev: cairo_dev only for cases when rendering to PDF?

I normally render the same .qmd file to both HTML and PDF. Setting knitr -> opts_chunk -> dev: cairo_pdf globally causes my HTML rendering to fail.

(By comparison, with RMarkdown you can invoke the device directly under the document-specific YAML: pdf(_document) -> dev: cairo_pdf Unless, I'm missing something, this doesn't work for Quarto.)

Thanks in advance.

[baptiste]

this should do the trick,

```{r setup, include=FALSE}
if (knitr::is_latex_output())
  knitr::opts_chunk$set(dev = "cairo_pdf")
```

[grantmcdermott]

Workaround confirmed. Thanks @baptiste!