How to create and display an animated GIF in Shiny?

Question

I'm able to load a saved file as an image but unable to use gganimate to do it directly. Alternate ways of rendering GIFs would be nice to know but knowing how to render gganimate specifically would really solve my problem.

library(gapminder)
library(ggplot2)
library(shiny)
library(gganimate)
theme_set(theme_bw())

ui <- basicPage(
    plotOutput("plot1")
)

server <- function(input, output) {
    output$plot1 <- renderPlot({
        p = ggplot(gapminder, aes(gdpPercap, lifeExp, size = pop, color = continent, frame = year)) +
  geom_point() +
  scale_x_log10()

       gg_animate(p)

    })

}

shinyApp(ui, server)

Answer 1

Now that there's a newer breaking version of gganimate, @kt.leap's answer is deprecated. Here's what worked for me with the new gganimate:

library(gapminder)
library(ggplot2)
library(shiny)
library(gganimate)
theme_set(theme_bw())

ui <- basicPage(
    imageOutput("plot1"))

server <- function(input, output) {
    output$plot1 <- renderImage({
    # A temp file to save the output.
    # This file will be removed later by renderImage
    outfile <- tempfile(fileext='.gif')

    # now make the animation
    p = ggplot(gapminder, aes(gdpPercap, lifeExp, size = pop, 
      color = continent)) + geom_point() + scale_x_log10() +
      transition_time(year) # New

    anim_save("outfile.gif", animate(p)) # New

    # Return a list containing the filename
     list(src = "outfile.gif",
         contentType = 'image/gif'
         # width = 400,
         # height = 300,
         # alt = "This is alternate text"
         )}, deleteFile = TRUE)}

shinyApp(ui, server)