Throw more informative warning if titlefont is detected and move from titlefont to title.font in ggplotly()

Author: cpsievert

R/ggplotly.R

@@ -429,9 +429,11 @@ gg2list <- function(p, width = NULL, height = NULL,
   )
   # main plot title
   if (nchar(plot$labels$title %||% "") > 0) {
-    gglayout$title <- faced(plot$labels$title, theme$plot.title$face)
-    gglayout$titlefont <- text2font(theme$plot.title)
-    gglayout$margin$t <- gglayout$margin$t + gglayout$titlefont$size
+    gglayout$title <- list(
+      text = faced(plot$labels$title, theme$plot.title$face),
+      font = text2font(theme$plot.title)
+    )
+    gglayout$margin$t <- gglayout$margin$t + gglayout$title$font$size
   }
   # ensure there's enough space for the modebar (this is based on a height of 1em)
   # https://github.com/plotly/plotly.js/blob/dd1547/src/components/modebar/index.js#L171

R/utils.R

@@ -516,6 +516,10 @@ verify_attr <- function(proposed, schema) {
 
 attrs_name_check <- function(proposedAttrs, validAttrs, type = "scatter") {
   illegalAttrs <- setdiff(proposedAttrs, validAttrs)
+  if ("titlefont" %in% illegalAttrs) {
+    warning("The titlefont attribute is now deprecated. Use title = list(font = ...) instead.", call. = FALSE)
+    illegalAttrs <- setdiff(illegalAttrs, "titlefont")
+  }
   if (length(illegalAttrs)) {
     warning("'", type, "' objects don't have these attributes: '",
             paste(illegalAttrs, collapse = "', '"), "'\n",