code-line-numbers and fragments not working as expected/hoped in revealjs

[rpruim]

Bug description

I would like to use `#| code-line-numbers and custom fragments to annotate revealjs slides, but I haven't been able to get it to work. Is this possible?

Here is the kind of thing I have in mind.

---
title: "code-line-numbers"
sbustitle: "and fragments"
format: revealjs
execute: 
  echo: true
---

## A slide

```{r}
#| code-line-numbers: "|1|2"
x <- 1
y <- 2
```

:::{.fragment fragment-index=1}
Comment on first line of code
:::

:::{.fragment fragment-index=2}
Comment on second line of code
:::

But when I view, the code highlighting is not synced up with the fragment indexing.

Steps to reproduce

No response

Expected behavior

No response

Actual behavior

No response

Your environment

R version 4.4.1 (2024-06-14)
Platform: aarch64-apple-darwin23.4.0
Running under: macOS Sonoma 14.4
RStudio: 2024.09.1+394 (2024.09.1+394)

Quarto check output

Quarto 1.5.56
[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.2.0: OK
Dart Sass version 1.70.0: OK
Deno version 1.41.0: OK
Typst version 0.11.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.5.56
Path: /Applications/quarto/bin

[✓] Checking tools....................OK
TinyTeX: (not installed)
Chromium: (not installed)

[✓] Checking LaTeX....................OK
Using: Installation From Path
Path: /opt/homebrew/bin
Version: undefined

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
Version: 3.12.4
Path: /Users/rpruim/.virtualenvs/r-reticulate/bin/python3
Jupyter: 5.7.2
Kernels: python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........OK
Version: 4.4.1
Path: /opt/homebrew/Cellar/r/4.4.1/lib/R
LibPaths:
- /opt/homebrew/lib/R/4.4/site-library
- /opt/homebrew/Cellar/r/4.4.1/lib/R/library
knitr: 1.49
rmarkdown: 2.29

[✓] Checking Knitr engine render......OK

[mcanouil]

code-line-numbers does not allow you to set fragment index, it creates an index for each line you set, so it is not expected for the code to have anything but a sequence of four elements in your case.
For instance, since you set manually index 1 and 2, it means first line will be index 3 and the second line will be index 4.

So, this would be a feature request to allow to manually set fragment index in addition to setting the lines.

Manual workaround + code annotation

---
title: "code-line-numbers"
format: revealjs
code-annotations: below
execute:
  echo: true
---

## A slide

```{r}
#| code-line-numbers: "1"
x <- 1 # <1>
```

1. Comment on first line of code


## A slide

```{r}
#| code-line-numbers: "2"
x <- 1 # <1>
y <- 2 # <2>
```

1. [Comment on first line of code]{style="opacity: 0.25;"}
2. Comment on second line of code

[rpruim]

Thanks for the reply. At least I know I wasn't overlooking a good way to achieve what I was after.

I've been using a similar manual work-around, but I don't like that I have to repeat content -- especially if I go back and edit the code and have to do it on multiple slides.

For my particular use case, it would suffice if I could create fragments that are indexed to match the code-line-numbers indexing. Coupled with repeating line blocks in code-line-numbers (if needed), this would allow for quite a range of combinations of code highlighting and fragment use.

Note: I've already written a custom fragment that uses

.reveal .slides section .fragment.current-only {
  display: none;
}

.reveal .slides section .fragment.current-only.current-fragment {
  display: inline
}

So my fragments can reuse the same space on the slide.

[DanChaltiel]

So, this would be a feature request to allow to manually set fragment index in addition to setting the lines.

This feature would be very useful, especially with incremental: true slides. Bullet points followed by code with highlighted lines are messing with each other.