Add selfcontained option to save_html()

[timelyportfolio]

I could have easily missed an easier solution, but saving a tagList especially as selfcontained = TRUE seems difficult. Here is the function I wrote to accomplish this using bits and pieces of htmltools. Would this be deemed as something worth of htmltools?

save_tags <- function (tags, file, selfcontained = F, libdir = "./lib") 
{
    if (is.null(libdir)) {
        libdir <- paste(tools::file_path_sans_ext(basename(file)), 
            "_files", sep = "")
    }
    htmltools::save_html(tags, file = file, libdir = libdir)
    if (selfcontained) {
        if (!htmlwidgets:::pandoc_available()) {
            stop("Saving a widget with selfcontained = TRUE requires pandoc. For details see:\n", 
                "https://github.com/rstudio/rmarkdown/blob/master/PANDOC.md")
        }
        htmlwidgets:::pandoc_self_contained_html(file, file)
        unlink(libdir, recursive = TRUE)
    }
    return(file)
}

[cpsievert]

Maybe it makes sense to have renderDependencies() have a self_contained arg (which would base64 encode the dependencies), so other functions, like renderDocument() can take advantage

[cpsievert]

What we should really do is basically copy https://github.com/ramnathv/htmlwidgets/blob/master/R/pandoc.R over to {htmltools} (and use it to implement htmltools::save_html(selfcontained = TRUE) which would mean htmlwidgets::saveWidget() could be a simple wrapper around htmltools::save_html())

Also, when we copy over the implementation, we should look into using {pandoc} over {rmarkdown} for pandoc_available() and pandoc_convert()

[cderv]

Just some thought about this

pandoc.R in htmlwidget seems to be adapted to work with rmarkdown::pandoc_self_contained_html

Forked from htmltools::save_html to work better with pandoc_self_contained_html

However, we need to revisit the function in {rmarkdown} rstudio/rmarkdown#2087, and maybe this is something to consider lower level and store in {pandoc}

I think we should try synchronize on this Carson when you think you'll tackle this.

[cpsievert]

@cderv I'm starting to look into this, and it does seem like having essentially the equivalent of

https://github.com/rstudio/rstudio/blob/0420c87/src/cpp/session/modules/ModuleTools.R#L375

(but with a sensible default for template?) exported by {pandoc} or {rmarkdown} would indeed be quite useful for {htmltools} (and thus {htmlwidgets}). That said, I may just experiment with a version that's local to {htmltools} for now and send you a PR (probably to {pandoc}?) if it feels general enough

[cderv]

Yes it feels to me general enough. We have rstudio/rmarkdown#2087 for rmarkdown function, so we need to rewrite this function. I agree.

[aloboa]

Is there a planned date for implementing this feature?
Meanwhile I'm using the suggested function (@ timelyportfolio thanks!), using rmarkdown::pandoc_available() and rmarkdown::pandoc_self_contained_html