How to download Rmarkdown report with multibyte character graph from shinyapps.io

Question

Situation

Hi. I'm trying to download the .pptx Rmarkdown report from shinyapps.io. The problem is, I want to download a graph with a multibyte character. (Japanese)

Since shinyapps.io does not provide Japanese font, I use the showtext package to render the graph with a multibyte character, and it works well with displaying in the browser.

However, when I try to download the .pptx file via downloadHandler() using rmarkdown::render, downloaded .pptx file come with Japanese font (and all the multibyte character within the font "collapsed".)

Reproducible example

#app.r
library(shiny)
library(tibble)
library(ggplot2)
library(magrittr)
library(showtext)

showtext.auto(TRUE)

ui <- fluidPage(
    downloadButton("dl","DL"),
    plotOutput("plot")
)

server <- function(input, output) {
    
    tempplot <- reactive({
        dat <- tibble(x = c("い","ろ","は"),
                      y = c(10,20,30))
        ggplot(dat) +
            geom_col(aes(x = x, y = y))
    })
    
    output$plot <- renderPlot({
        tempplot()
    })
    
    output$dl <- downloadHandler(
        filename = function(){"test.pptx"},
        content  = function(con){
            rmarkdown::render(input = "test.Rmd",
                              output_file = con)
        }
    )
}

shinyApp(ui = ui, server = server)

#global.R
library(shiny)
library(tibble)
library(ggplot2)
library(magrittr)
library(showtext)

#test.Rmd

---
title: "test"
output: powerpoint_presentation
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
```

## マルチバイト文字

```{r}
tempplot()
```

Result

This is what displayed in the application at shinyapps.io. Multibyte characters are displayed as intended.

Whereas, downloaded .pptx file is as follows.

Question

Is there any way I can download the .pptx file with multibyte character from shinyapps.io? (As displayed in the app in shinyapps.io.

Answer 1

what if you tried

---
title: "test"
output: powerpoint_presentation
    self_contained: yes
    mode: selfcontained
---

in your .Rmd file or maybe just

---
title: "test"
output: powerpoint_presentation
    self_contained: yes
---

This is suppose to encapsulate the entire document into a file with all the information it needs to regenerate, but I haven't used it with .pptx files

Answer 2

After some extra search, I found the solution.

This web page explains what I needed.

I just needed to add fig.showtext = TRUE to the chunk to apply the showtext package's effect to the graph within the rmarkdown.