geom_NewGeomContour() has yet to be implemented in plotly

[PhKoch]

When plotting a ggplot object "improved" with a second scale using https://github.com/eliocamp/ggnewscale a warning is printed and only the last geom is included in the plotly figure.

Herewith I'm following the advice from the Warning and opened this issue :-)

It would be great if someone may extend plotly in this direction.

Reprex:

library(ggplot2)
library(ggnewscale)
# Equivalent to melt(volcano)
topography <- expand.grid(x = 1:nrow(volcano),
                          y = 1:ncol(volcano))
topography$z <- c(volcano)

# point measurements of something at a few locations
set.seed(42)
measurements <- data.frame(x = runif(30, 1, 80),
                           y = runif(30, 1, 60),
                           thing = rnorm(30))

p <- ggplot(mapping = aes(x, y)) +
  geom_contour(data = topography, aes(z = z, color = stat(level))) +
  # Color scale for topography
  scale_color_viridis_c(option = "D") +
  # geoms below will use another color scale
  new_scale_color() +
  geom_point(data = measurements, size = 3, aes(color = thing)) +
  # Color scale applied to geoms added after new_scale_color()
  scale_color_viridis_c(option = "A")

# fine:
p

# warning & incomplete plot:
plotly::ggplotly(p)

Taken from: https://github.com/eliocamp/ggnewscale/blob/master/README.md

Warning:

This version of Shiny is designed to work with 'htmlwidgets' >= 1.5.
    Please upgrade via install.packages('htmlwidgets').
Warning message:
In geom2trace.default(dots[[1L]][[1L]], dots[[2L]][[1L]], dots[[3L]][[1L]]) :
  geom_NewGeomContour() has yet to be implemented in plotly.
  If you'd like to see this geom implemented,
  Please open an issue with your example code at
  https://github.com/ropensci/plotly/issues

Environment:

>R.version           
platform       x86_64-pc-linux-gnu         
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          3                           
minor          5.3                         
year           2019                        
month          03                          
day            11                          
svn rev        76217                       
language       R                           
version.string R version 3.5.3 (2019-03-11)
nickname       Great Truth

> packageVersion("plotly")
[1] ‘4.9.0’

[cpsievert]

Thanks for the reprex. Added to #566