Add reportTheme arg to shinyWidgetOutput()

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: htmlwidgets
 Type: Package
 Title: HTML Widgets for R
-Version: 1.5.1.9000
+Version: 1.5.1.9001
 Authors@R: c(
     person("Ramnath", "Vaidyanathan", role = c("aut", "cph")),
     person("Yihui", "Xie", role = c("aut")),
@@ -25,4 +25,4 @@ Suggests:
 Enhances: shiny (>= 1.1)
 URL: https://github.com/ramnathv/htmlwidgets
 BugReports: https://github.com/ramnathv/htmlwidgets/issues
-RoxygenNote: 6.1.1
+RoxygenNote: 7.0.2

R/htmlwidgets.R

@@ -358,6 +358,8 @@ createWidget <- function(name,
 #'   function.
 #' @param reportSize Should the widget's container size be reported in the
 #'   shiny session's client data?
+#' @param reportTheme Should the widget's container styles (e.g., colors and fonts)
+#' be reported in the shiny session's client data?
 #' @param expr An expression that generates an HTML widget (or a
 #'   \href{https://rstudio.github.io/promises/}{promise} of an HTML widget).
 #' @param env The environment in which to evaluate \code{expr}.
@@ -386,13 +388,27 @@ createWidget <- function(name,
 #'
 #' @export
 shinyWidgetOutput <- function(outputId, name, width, height, package = name,
-                              inline = FALSE, reportSize = FALSE) {
+                              inline = FALSE, reportSize = FALSE, reportTheme = FALSE) {
 
   checkShinyVersion()
+
+  # Theme reporting requires this shiny feature
+  # https://github.com/rstudio/shiny/pull/2740/files
+  if (reportTheme &&
+      nzchar(system.file(package = "shiny")) &&
+      packageVersion("shiny") < "1.4.0.9003") {
+    message("`reportTheme = TRUE` requires shiny v.1.4.0.9003 or higher. Consider upgrading shiny.")
+  }
+
   # generate html
   html <- htmltools::tagList(
-    widget_html(name, package, id = outputId,
-      class = paste0(name, " html-widget html-widget-output", if (reportSize) " shiny-report-size"),
+    widget_html(
+      name, package, id = outputId,
+      class = paste0(
+        name, " html-widget html-widget-output",
+        if (reportSize) " shiny-report-size",
+        if (reportTheme) " shiny-report-theme"
+      ),
       style = sprintf("width:%s; height:%s; %s",
         htmltools::validateCssUnit(width),
         htmltools::validateCssUnit(height),

inst/NEWS

@@ -3,6 +3,8 @@ htmlwidgets 1.5.1.9000
 
 * Fixed an issue with passing named function declarations to `JS()` and `onRender()` (introduced by v1.4). (#356)
 
+* Added a `reportTheme` argument to `shinyWidgetOutput()`. If `TRUE`, CSS styles of the widget's output container are made available to `shiny::getCurrentOutputInfo()`, making it possible to provide 'smart' styling defaults in a `renderWidget()` context. (#361)
+
 htmlwidgets 1.5.1
 -------------------------------------------------------