Alternative text for GFM output

[maelle]

Description

If I render the following Quarto document

---
title: "Untitled"
format: gfm
---


```{r plotting}
#| fig-alt: "An example plot"
plot(1:10)
```

I get

# Untitled


``` r
plot(1:10)
```

<img src="Untitled-1_files/figure-commonmark/plotting-1.png"
data-fig-alt="An example plot" />

I'd expect the alternative text to be in alt not data-fig-alt. I assume I am missing something obvious but can't tell what so am asking here. 🙏

[mcanouil]

This feels like a bug.

Note that you should avoid mixing syntaxes for options. You are using both R inline and YAML style syntax. In Quarto, it's pretty simple: a code cell has nothing but the language inside the brackets.

```{r}
#| label: plotting
#| fig-alt: "An example plot"
plot(1:10)
```

[maelle]

Thank you for your answer and reminder!

Should I open an issue then?

[mcanouil]

By the way, for GitHub Flavoured Markdown, alt does not exist.

The markdown syntax is: ![alt text](image.png), so the code cell would be:

---
title: "Untitled"
format: gfm
---

```{r}
#| label: plotting
#| fig-cap: "An example plot"
plot(1:10)
```

[mcanouil]

So, it feels like a bug but it's not really one.
I'm checking if this is specific to knitr.

edit: the behaviour is the same across engines.
Now the question is: should fig-alt value be used as "caption" for gfm format? What should be the behaviour if fig-cap is also provided? 🤷‍♂️

[maelle]

For context, I'm trying to use Quarto to create a Markdown document suitable for Jekyll.

Even for "hugo" the output seems to be data-fig-alt.

But in any case yes fig-cap creates something more usable for Jekyll, thank you!

[mcanouil]

cc. @cderv @cscheid

[cderv]

I think we are just not handling fig-alt (which is a quarto image attribute https://quarto.org/docs/authoring/figures.html#alt-text) for gfm format. 🤔

---
title: "Untitled"
format: gfm
---

![](surus.png){fig-alt='A placeholder image'}

gives

# Untitled


<img src="surus.png" data-fig-alt="A placeholder image" />

which seems unexpected to me

• fig-alt attributes is not correctly processed on image for gfm output. #12456