Transparent background for ggplots

[snhansen]

Description

The following used to create plots with a transparent background but doesn't anymore (at least on in Quarto 1.8.25). Did anything change or did I forget to set something up with my fresh Quarto installation?

---
format: revealjs
---

## Title {background-color="aquamarine"}

```{r}
#| dev.args: 
#|   bg: "transparent"
library(ggplot2)
ggplot(data = mtcars, aes(x = hp, y = mpg)) +
  geom_point() +
  theme_minimal()
```

```{r, dev.args=list(bg="transparent")}
library(ggplot2)
ggplot(data = mtcars, aes(x = hp, y = mpg)) +
  geom_point() +
  theme_minimal()
```

[mcanouil]

This is handled mostly by knitr and the R default graphic device being used.
All this depends on the R version, version of knitr, version of ggplot2 (recently released as 4.0.0) among other things.

Could you develop your example to ensure the environment is known? For instance, what does "The following used to create plots with a transparent background but doesn't anymore (at least on in Quarto 1.8.25)" mean exactly? What was the setup where it worked?

[mcanouil]

Also are you sure the plot has no background? bg is the background of the graphics device, not the plot, thus if the plot has a background, then you won't see the transparent background underneath.

Taking a look at ggplot2 4.0.0 theme_minimal():

• https://github.com/tidyverse/ggplot2/blob/a951f4fb0597fe99098ab7e286bd83ecb8248173/R/theme-defaults.R#L451-L480

The plot background is set to paper which is set to paper = "white".

So, I'm guessing you updated ggplot2 and missed the part of the changelog talking about the new ink and paper arguments.

---
format: revealjs
---

## Title {background-color="aquamarine"}

```{r}
#| dev-args: 
#|   bg: "transparent"
library(ggplot2)
ggplot(data = mtcars, aes(x = hp, y = mpg)) +
  geom_point() +
  theme_minimal(paper = "transparent")
```

[snhansen]

Yeah, it's the introduction of the paper-argument that is the issue here. Thanks for pointing me in that direction and sorry about the fuss.