shiny downgrade fontawesome 5 to 4 - r

Question

I work on a shiny project quite entangled with fontawesome 4.7, and it has brought us great value. As a free user of fontawesome, I don't see we have any advantage of upgrading to 5.3.1. Many of the free icons have become uglier/cruder, and one would have to pay for the pro version to get the icon styles similar to 4.7.
Example table available in 4.7 with 9 cells
in 5.3 table is onle free as 4 cells and rather chubby lines. The old 9 cell format is only available for pro users
From my own simple perspective, it seems the fontawesome team intends to strongly nudge their free users to go pro.
Rstudio shiny 1.1 links to fontawesome 4.7.1
Rstudio shiny 1.2 links to fontawesome 5.3.1
Are there any easy ways to both have shiny 1.2 and fontawesome 4.7.1?
EDIT
Link by pork chop seems very relevant, I will try it out and update...

Answer 1

Download fontawesome 4.7.1 & unzip
insert code below in global.R
update path to unzipped fontawesome
.... and then shiny can do both fontawesome 4.7.1 and +5. This specific solution copies as suggested by Pork Chop old version of font-awesome in installed shiny library. Also I updated the icon()-function so it is possible to have fontawesome versions to coexist and to ensure correct linking. In this solution a new icon() function is placed in globalEnv hence in top of search()-path. That saved my code base legacy issues without changing anything else.
However for making a new shiny-application, I would name icon-function icon_legacy() to avoid relying on search()-path or implement in a support R-package for shiny-application.
##install new shiny version
install.packages("shiny") #install newest shiny
library(shiny)
library(htmltools)
#source in this function to globalEnv
#' Legacy means good old iconic times
#'
#' #param local_path_fa_4.7.1
#' #param shiny_path
#'
#' #return
#' #export
#' #import shiny htmltools
#' #details #this installs legacy font-awesome and return a function similar to icon
#'
#' #examples
#'
#' install.packages("shiny") #install newest shiny
#' library(shiny)
#' library(htmltools)
#' my_fa_path = "./misc/global_source/fa_shiny_4.7.1/font-awesome"
#' icon_legacy = activate_icon_legacy(my_fa_path) #tadaaa use icon_legacy now
#' #btw css pseudo-elements seem to work out-of-the-box also
#'
#' icon = icon_legacy #you may also feel like placing icon in global env to override shiny::icon
activate_icon_legacy = function(
local_path_fa_4.7.1,
shiny_path = system.file(package="shiny")
) {
#find out what version of shiny is installed
uses_fontawesome5 = packageVersion("shiny")>=1.2 #because implemented since 1.2
shiny_resource_path = paste0(shiny_path,"/www/shared")
misses_fontawesome4 = !"font-awesome" %in% list.files(shiny_resource_path) #because new fa dir is called 'fontawesome'
#if legacy dir is missing from library copy into installed library
if(uses_fontawesome5 && misses_fontawesome4) {
file.copy(
from = local_path_fa_4.7.1,
to = shiny_resource_path,
recursive = TRUE,copy.mode = FALSE
)
}
#import minor dependency from shiny library into closure
font_awesome_brands = shiny:::font_awesome_brands
tags = htmltools::tags
#source this modified icon() function from library/shiny/R/bootstrap.R
#notice the legacy feature if true will use old fa 4.7.1 else new
icon_legacy <- function(name, class = NULL, lib = "font-awesome",legacy=TRUE) {
prefixes <- list(
"font-awesome" = "fa",
"glyphicon" = "glyphicon"
)
prefix <- prefixes[[lib]]
# determine stylesheet
if (is.null(prefix)) {
stop("Unknown font library '", lib, "' specified. Must be one of ",
paste0('"', names(prefixes), '"', collapse = ", "))
}
# build the icon class (allow name to be null so that other functions
# e.g. buildTabset can pass an explicit class value)
iconClass <- ""
if (!is.null(name)) {
prefix_class <- prefix
if (prefix_class == "fa" && name %in% font_awesome_brands) {
prefix_class <- "fab"
}
iconClass <- paste0(prefix_class, " ", prefix, "-", name)
}
if (!is.null(class))
iconClass <- paste(iconClass, class)
iconTag <- tags$i(class = iconClass)
# font-awesome needs an additional dependency (glyphicon is in bootstrap)
if (lib == "font-awesome") {
if(legacy) {
htmlDependencies(iconTag) <- htmlDependency(
"fontwesome","4.7.1", "www/shared/font-awesome", package = "shiny",
stylesheet = c("css/font-awesome.css","font-awesome.min.css"))
} else {
htmlDependencies(iconTag) <- htmlDependency(
"font-awesome", "5.3.1", "www/shared/fontawesome", package = "shiny",
stylesheet = c("css/all.min.css","css/v4-shims.min.css")
)
}
}
htmltools::browsable(iconTag)
}
return(icon_legacy)
}
#download extract fontawesome 4.7.1 and write path here
my_fa_path = "./misc/global_source/fa_shiny_4.7.1/font-awesome"
icon_legacy = activate_icon_legacy(my_fa_path) #tadaaa use icon_legacy now
#btwcss pseudos seem to work out-of-the-box also
#one may also feel like placing icon_legacy() as icon() in globalEnv to override shiny::icon
#if youre too lazy change all your original code. This will work any code in ui.R and server.R
#however packages with explicit namespaces are likely not overridden by this.
icon = icon_legacy
#now shiny code will behave like this
icon("table",legacy=TRUE) # old style 9 cell table
icon("table",legacy=FALSE) # new fat 4 cell table
#...one may feel like opting for more explicit and strict namespace solution wrapped in some package.
#but that would be a lot more boiler plate code not relevant for this answer
#this solution also fixed my fontawesome CSS pseudo-elements issues