htmlwidget-webshot-example.R

highcharter-htmlwidget-webshot-example.R

# Creating html plots with highcharter and generating high resolution PNGs of plots with webshot

library(highcharter)

# set up directories
OUTPUT_HTML <- '~/Downloads/hc-webshot-example/html'
OUTPUT_PNG <- '~/Downloads/hc-webshot-example/png'
if(!dir.exists(OUTPUT_HTML)) dir.create(OUTPUT_HTML, recursive = TRUE)
if(!dir.exists(OUTPUT_PNG)) dir.create(OUTPUT_PNG, recursive = TRUE)

FILE <- 'drivers_killed'
DF <- Seatbelts %>%
  tibble::as_tibble() %>%
  tibble::rownames_to_column('ym') %>%
  dplyr::mutate(ym = time(Seatbelts) %>% zoo::as.yearmon())

# output an html version on what your plot
html <- file.path(OUTPUT_HTML, paste0(FILE, ".html"))
message(sprintf("Exporting... %s", html))
hc <- hchart(DF, "line", hcaes(x = ym, y = DriversKilled)) %>%
  hc_title(text = paste("Drivers Killed")) %>%
  hc_yAxis(title = list(text = "Drivers Killed"), min = 0) %>%
  hc_plotOptions(series = list(animation = FALSE)) # turn off animation so plots render quickly
htmlwidgets::saveWidget(hc, file = html, libdir = 'html_support_files') # save html widget

# make pngs
htmls <- list.files(OUTPUT_HTML, pattern = "html$", full.names = TRUE) # find list of all html files
pngs <- lapply(htmls, function(j) { # search folder for html widgets, convert to png

  dir <- normalizePath(OUTPUT_PNG)
  out <- file.path(dir, gsub("html", "png", basename(j))) # copy names, remove html, add png

  # user webshot to generate pngs
  message(sprintf("Generating... %s", out))
  webshot::webshot(j, file = out, delay = 0, vwidth = 1500, vheight=500, zoom=2)
})