renderImage example for Shiny

server.r

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

    # Generate the PNG
    png(outfile, width=400, height=300)
    hist(rnorm(input$obs), main="Generated in renderImage()")
    dev.off()

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

ui.r

shinyUI(pageWithSidebar(
  headerPanel("renderImage example"),
  sidebarPanel(
    sliderInput("obs", "Number of observations:", 
                min = 0, max = 1000,  value = 500)
  ),
  mainPanel(
    imageOutput("myImage")
  )
))