R chrome_print() landscape = T not resizing HTML on print?

I am creating a report in my R Shiny app that sends parameters to knit a html file and then runs chrome_print() on that to convert it to a PDF. The reason it is done this way is because I want to send my echarts4r widgets as parameters to save compute time and maintain SVG lossless quality.

The issue I am having is that when I set landscape = T it does not seem to adjust the widget to the width of the print area. It does print to the correct width when performing the operation manually through a non headless browser.

Here is a minimal example below:

R Markdown ``` --- title: "Untitled" author: "fullera" date: "r Sys.Date()" output: html_document ---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
Output the plot
mtcars |>
e_charts(cyl,renderer = 'svg') |>
e_line(mpg) |> e_animation(show = F)
```

R Code ``` library(echarts4r) library(pagedown)

pagedown::chrome_print(input = 'untitled.html', output = 'foo.pdf', options = 
list(landscape=T))
```

Solution

I ended up solving this by using the chromote package

More details at the URL: https://nanx.me/blog/post/chromote-pdf-automation/

library("promises")
library("chromote")

#' Print HTML to PDF using chromote
#'
#' @param url Input URL
#' @param filename Output file name
#' @param wait_ If TRUE, run in synchronous mode,
#' otherwise, run in asynchronous mode.
#' @param ... Additional parameters for Page.printToPDF, see
#' <https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-printToPDF>
#' for possible options.
print_to_pdf <- function(url, filename = NULL, wait_ = FALSE, ...) {
  if (is.null(filename)) {
    filename <- url |>
      gsub("^.*://", "", x = _) |>
      gsub("/$", "", x = _) |>
      fs::path_sanitize(replacement = "_") |>
      paste0(".pdf")
  }
  
  b <- ChromoteSession$new()
  
  p <-
    {
      b$Page$navigate(url, wait_ = FALSE)
    } %...>%
    {
      b$Page$loadEventFired(wait_ = FALSE, timeout_ = 2000)
    } %...>%
    {
      b$Page$printToPDF(..., wait_ = FALSE,landscape = T)
    } %...>%
    {
      .$data
    } %...>%
    {
      outfile <- file(filename, "wb")
      base64enc::base64decode(., output = outfile)
      close(outfile)
    } %...>%
    {
      message(filename)
    } %>%
    finally(~ b$close())
  
  if (wait_) {
    b$wait_for(p)
  } else {
    p
  }
  
  invisible(filename)
}





f <- "https://nanx.me/blog/post/r-readability-parser/example.html" |>
  curl::curl_download(destfile = 'downloaded.html')


print_to_pdf(
  paste0("file://", normalizePath(f, winslash = "/")),
  filename = "example.pdf",
  wait_ = TRUE
)