New imgur_upload with xml2 and httr (#1433)

* use xml2 and httr for imgur_upload

* generate documentation

* add packages to suggests

* stop upload if pkg not installed

* use internal function to check package

* Revert "generate documentation"

This reverts commit b1d655b.

* do not check for package installation

* assume encoding is UTF8

* add myself as new contributor

DESCRIPTION

@@ -15,6 +15,7 @@ Authors@R: c(
     person("Ben", "Baumer", role = "ctb"),
     person("Brian", "Diggs", role = "ctb"),
     person("Cassio", "Pereira", role = "ctb"),
+    person("Christophe", "Dervieux", role = "ctb"),
     person("David", "Robinson", role = "ctb"),
     person("Donald", "Arseneau", role = c("ctb", "cph"), comment = "the framed package at inst/misc/framed.sty"),
     person("Doug", "Hemken", role = "ctb"),
@@ -109,6 +110,8 @@ Suggests:
     png,
     jpeg,
     XML,
+    xml2,
+    httr,
     RCurl,
     DBI (>= 0.4-1),
     tibble

R/utils-upload.R

@@ -1,7 +1,7 @@
 #' Upload an image to imgur.com
 #'
-#' This function uses the \pkg{RCurl} package to upload a image to
-#' \url{imgur.com}, and parses the XML response to a list with \pkg{XML} which
+#' This function uses the \pkg{httr} package to upload a image to
+#' \url{imgur.com}, and parses the XML response to a list with \pkg{xml2} which
 #' contains information about the image in the Imgur website.
 #'
 #' When the output format from \code{\link{knit}()} is HTML or Markdown, this
@@ -35,13 +35,17 @@
 #' opts_knit$set(upload.fun = function(file) imgur_upload(file, key = 'your imgur key'))
 #' }
 imgur_upload = function(file, key = '9f3460e67f308f6') {
+
   if (!is.character(key)) stop('The Imgur API Key must be a character string!')
-  res = RCurl::postForm(
-    'https://api.imgur.com/3/image.xml', image = RCurl::fileUpload(file),
-    .opts = RCurl::curlOptions(httpheader = c(Authorization = paste('Client-ID', key)),
-                               cainfo = system.file("CurlSSL", "cacert.pem", package = "RCurl"))
+  resp <- httr::POST(url = "https://api.imgur.com/3/image.xml",
+                     config = httr::add_headers(Authorization = paste("Client-ID", key)),
+                     body = list(image = httr::upload_file(file)))
+  httr::stop_for_status(resp, task = "Fail to upload")
+  info_media <- httr::parse_media(resp$headers[["Content-Type"]])
+  if (info_media$complete != "text/xml") stop("Fail to upload; response is not XML")
+  res <- xml2::as_list(
+    xml2::read_xml(x = httr::content(resp, as = "raw"))
   )
-  res = XML::xmlToList(res)
-  if (is.null(res$link)) stop('failed to upload ', file)
-  structure(res$link, XML = res)
+  if (is.null(res$link[[1]])) stop('failed to upload ', file)
+  structure(res$link[[1]], XML = res)
 }