Have ggplotly() replace default fonts with thematic's font option (#1804)

* Have ggplotly() replace default fonts with thematic's font option (if set), closes #1803

* bump docker image to R 4.0

Author: cpsievert

R/ggplotly.R

@@ -1258,12 +1258,31 @@ bbox <- function(txt = "foo", angle = 0, size = 12) {
 text2font <- function(x = ggplot2::element_text(), type = "height") {
   list(
     color = toRGB(x$colour),
-    family = x$family,
+    family = font_family(x$family),
     # TODO: what about the size of vertical text?
     size = unitConvert(grid::unit(x$size %||% 0, "points"), "pixels", type)
   )
 }
 
+# Replace a default font family, "", with thematic's font option (if set)
+font_family <- function(family = "") {
+  if (!identical(family, "")) {
+    return(family)
+  }
+  if (!isNamespaceLoaded("thematic")) {
+    return("")
+  }
+  font <- thematic::thematic_get_option("font")
+  if (!length(font)) {
+    return("")
+  }
+  # font$families is a vector of families, but font.family wants to be a 
+  # string (like CSS font-family), so make sure the names are unquoted, 
+  # then quote them
+  families <- sub("'$", "", sub("^'", "", font$families))
+  sprintf("'%s'", paste(families, collapse = "', '"))
+}
+
 # wrap text in bold/italics according to the text "face"
 faced <- function(txt, face = "plain") {
   if (is.null(face)) face <- "plain"

inst/docker/Dockerfile.vtest

@@ -11,7 +11,7 @@ ARG CACHEBUST=1
 
 # Need this to add R repo
 RUN apt-get update && apt-get install -y software-properties-common apt-transport-https \
- && add-apt-repository "deb https://cloud.r-project.org/bin/linux/ubuntu xenial-cran35/" \
+ && add-apt-repository "deb https://cloud.r-project.org/bin/linux/ubuntu xenial-cran40/" \
  && apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9 \
  && apt-get update && apt-get install -y \
     sudo \

tests/figs/axes/ticktext-linebreaks.svg

@@ -1,3 +1,3 @@
 - vdiffr-svg-engine: 1.0
-- vdiffr: 0.3.1.9000
+- vdiffr: 0.3.2
 - freetypeharfbuzz: 0.2.5