Different html rendering when output is set to epub2

[flipacholas]

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My session:

R version 4.2.1 (2022-06-23)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Big Sur ... 10.16

Locale: en_GB.UTF-8 / en_GB.UTF-8 / en_GB.UTF-8 / C / en_GB.UTF-8 / en_GB.UTF-8

Package version:
  base64enc_0.1.3 bslib_0.3.1     digest_0.6.29   evaluate_0.15  
  fastmap_1.1.0   fs_1.5.2        glue_1.6.2      graphics_4.2.1 
  grDevices_4.2.1 highr_0.9       htmltools_0.5.2 jquerylib_0.1.4
  jsonlite_1.8.0  knitr_1.39      magrittr_2.0.3  methods_4.2.1  
  R6_2.5.1        rappdirs_0.3.3  rlang_1.0.3     rmarkdown_2.14 
  sass_0.4.1      stats_4.2.1     stringi_1.7.6   stringr_1.4.0  
  tinytex_0.40    tools_4.2.1     utils_4.2.1     xfun_0.31      
  yaml_2.3.5     

Pandoc version: 2.18

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I think there is (undesirable?) behaviour present when rendering epubs using the epub_version attribute set to epub2. Basically, after embedding images on a document with caption (using fig.caption), if the document is rendered using bookdown and epub_version is set to epub3 or epub, knitr will render <p class="caption"> block with the caption (as expected). On the other hand, if it's set to epub2, the caption block is not rendered.

At first, I thought this was an issue of bookdown, but I found this line that may be the culprit:

knitr/R/utils.R

Line 382 in 17ef462

fmts = c('markdown', 'epub', 'html', 'html4', 'html5', 'revealjs', 's5', 'slideous', 'slidy', 'gfm')

(probably should include "epub2" as well?)

[yihui]

Yes, it should include epub2. Would you like to send a pull request? Thanks!

[flipacholas]

Done!

[github-actions]

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