Semi-transparency is not supported

[Jonathan Koerner]

When rendering a ggplot with semi transparancy (0 >alpha <1).  I get the following warning:

Warning in grid.Call.graphics(L_polygon, x$x, x$y, index) :

  semi-transparency is not supported on this device: reported only once per page

I am able to see a correct version when calling x11(type ="cairo"); however, the proper image doesn't make it on to the shiny.

 

The ggplot command is ggplot(data) + geom_density(aes(x=value, fill=variable),alpha = 0.3).

Anyone have a work around?

[Pete St Marie]

Possibly this: http://tinyheero.github.io/2015/09/15/semi-transparency-r.html

Or if it's happening in RStudio: https://stackoverflow.com/questions/22581567/semi-transparency-in-rstudio

N.B., these were the top two results from just Google searching the complete text of the warning.

--pete