R/addins.R

In SciViews/learndown: R Markdown, Bookdown and Learnr Additions for Learning Material

# RStudio addins


# Shiny Application Webshot -----------------------------------------------

webshot_shiny_addin <- function() {
  # Get the active document
  ctx <- rstudioapi::getActiveDocumentContext()

  # Checks that a document is active
  if (!is.null(ctx)) {

    # Extracts selection as a string
    sel <- ctx$selection[[1]]$text

    # Check that the selection contains something like a call to a function
    if (!grepl("^[^\\(]+(\\([^\\)]+\\)).*$", sel)) {
      message("You must select a construct like 'launch_shiny(url, ...)', ",
        "or select a PNG file with the screenshot now...")

      screenshot <- rstudioapi::selectFile(
        "Select the Shiny app screenshot in PNG format",
        filter = "PNG images (*.png)", existing = TRUE)
      if (is.null(screenshot))
        return()
      # Construct the composite image
      res <- try(img <- learnitdown::webshot_shiny(screenshot), silent = TRUE)
    } else {# We have to launch the app and make the screenshot
      # Get what looks like the arguments
      args <- sub("^[^\\(]+(\\([^\\)]+\\)).*$", "\\1", sel)

      # Construct the code to take screenshot of the Shiny app and run it
      message("Launching the Shiny application and taking the screenshot,",
        " please wait...")
      img <- NULL
      code <- paste0("img <- learnitdown::webshot_shiny", args)
      res <- try(eval(parse(text = code)), silent = TRUE)
    }

    # Is there an error?
    if (inherits(res, "try-error")) {
      message("An error occured while trying to take Shiny app screenshot")
      message(res)
    } else if (is.null(img)) {
      # No screenshot was created
      message("The screenshot was not created, check your code!")
    } else {
      # Check result and display the image and a message to the R console
      message("Screenshot created in: ", img)
      print(magick::image_read(img))
    }
  }
}