Saving an echarts4r image via code (again)

Question

I asked this question earlier here, but it was marked as duplicate and closed. Unfortunately the answer I was pointed to doesn't work....

So, again:

I can produce an eCharts4r gauge like

library(echarts4r) 
library(magrittr)

CA_gauge <- e_charts() %>% 
  e_gauge(4.1, 
          "INCIDENCE", 
          min=0, 
          max=20,
          axisLine = list(
            linestyle = list(
              color=list(
                c(1.5/20, "green"),
                c(3/20, "yellow"),
                c(1, "red")
              )
            ))) %>% 
  e_title("CA")

print(CA_gauge)

But I haven't found a good way to save the output to a file so that I can use it later in a gt table. The best I have been able to find is to add the "saveAsImage" to the output

e_charts() %>% 
      e_gauge(4.1, 
              "INCIDENCE", 
              min=0, 
              max=20,
              axisLine = list(
                linestyle = list(
                  color=list(
                    c(1.5/20, "green"),
                    c(3/20, "yellow"),
                    c(1, "red")
                  )
                ))) %>% 
        e_toolbox_feature(feature = c("saveAsImage"))

That adds a saveAs button in the upper right of the RStudio viewer

But what I'd really like to do is just save the image (obviously without animation) in code to a tiff/jpg/png image file. I have been producing about a dozen of these a week for a work project, so I have been manually saving the files. But they're kind of a hit and the boss wants a new version with 75+ of these.

I tried using the standard devices like

tiff(paste("CA_gauge.tif",sep=""), 
     res=600, compression = "lzw", height=5, width=15, units="in")
print(CA_gauge)
dev.off()

But that doesn't do it...all I get is an all white tif file. The answer that I was pointed to when my original thread was closed suggested using htmlwidgets and webshot. Following that example I came up with

CA_gauge <- e_charts() %>% 
  e_gauge(round(CA_data[[nrow(CA_data), 10]],1), 
          "CA \nINCIDENCE", 
          animation = FALSE,
          min=0, 
          max=20,
          animation = FALSE,
          axisLine = list(
            lineStyle = list(
              color=list(
                c(1.5/20, "green"),
                c(3/20, "yellow"),
                c(1, "red")
              )
            )))

htmlwidgets::saveWidget(widget = CA_gauge, file = "~/plot.html")
setwd("~")
webshot::webshot(url = "plot.html", 
                 file = "plot.png")

This produces two output files: plot.html and plot.png

Plot.html is a whole lot of JavaScript that looks like this in a browser

Which is all well and good, but plot.png is a 5kb .png file that is empty as far as I can tell....it shows up as a white screen when you try to open it, jsut like what I get from trying to use the standard devices.

Any suggestions?

Answer 1

I had the same problems using webshot, but webshot2 seems to work.

webshot2 from rstudio's github

library(echarts4r) 
library(magrittr)
library(webshot2)
library(htmlwidgets)

CA_gauge <- e_charts() %>% 
  e_gauge(4.1, 
          "INCIDENCE", 
          min=0, 
          max=20,
          axisLine = list(
            linestyle = list(
              color=list(
                c(1.5/20, "green"),
                c(3/20, "yellow"),
                c(1, "red")
              )
            ))) %>% 
  e_title("CA")

htmlwidgets::saveWidget(widget = CA_gauge, file = "~/ca_gauge.html")

# I had to set this for webshot2 to work on Ubuntu 20.04 LTS
# Sys.setenv(CHROMOTE_CHROME = '/snap/bin/chromium')
#  use 'Sys.which("chromium")' to get your path.

webshot('ca_gauge.html', file = 'ca_gauge.png')

The files in a file browser:

Output .png: