Directly include Base64-encoded images in .qmd

[zeileis]

Description

When I include Base64-encoded images directly in .qmd files, they are not rendered correctly. When I just do

![](data:image/png;base64,i [...snip...] =)

Then a .png suffix is added at the end in the <img =src".."> which does not work.

Additionally, in some contexts I get the file name too long (os error 36) error, similar to #4613.

A minimal example replicating the first issue using quarto 1.3.450 and R package base64enc is:

Output of `image(volcano)` in Base64:
```{r}
#| echo: false
#| results: "asis"
## create PNG file
img <- tempfile(fileext = ".png")
png(img)
image(volcano)
dev.off()

## write as base 64
img64 <- sprintf("![](%s)", base64enc::dataURI(file = img, mime = "image/png"))
writeLines(img64)
```

I wasn't able to pinpoint exactly when I get the file name too long error. I only get it with Opengraph/Twitter enabled in _quarto.yml but only in my actual website and not in a minimal fresh website. I can try to dig deeper in case this is needed.

[cscheid]

I see Pandoc is definitely appending a .png to the end of our data URIs, and that is 100% a bug we need to fix. I'll open an issue.

[mcanouil]

Closing in favour of:

• Directly include Base64-encoded images in .qmd #6568