r - Making pie chart's contours smoother on Shiny -

i trying have nice looking plot 2 (or possibly more) continuous values in form of pie chart using ggplot2.
code following :

library("ggplot2") library("ggthemes") ## theme_economist df <- data.frame(origin=c('with','without'),value=c(24536,50456))   pie <- ggplot(df, aes(x = "",y=value, fill = origin))+       geom_bar(width = 1,stat="identity")+       coord_polar(theta = "y",start=pi/3)+       theme_economist() 

pie relatively fine except contours of pie seems bit irregularly drawn.of course when export pdf looks fine displayed in rstudio or shiny doesn't nice @ all.
there way change resolution of ggplot object directly or make renderplot() aware want display image @ high resolution ? tried modifying res argument of renderplot() function distorts image , not rid of irregularity of border.

how make contours of pie smoother on shiny or rstudio directly ? thanks.

to improve resolution of plot on shiny have set res argument default value of 72. not make lot of sense me worked fine resolution went bad nice !
increasing value further can lead distortion of image.
seems cannot change resolution of plotting object before exporting or rendering shiny.