Download Plotly using downloadHandler

Question

i got stuck at some point while trying to use downloadHandler to download Plotly images. I just cannot figure out further how to get the image from temp directory...

Here is a sample code:

library(shiny)
library(plotly)
library(rsvg)
library(ggplot2)

d <- data.frame(X1=rnorm(50,mean=50,sd=10),X2=rnorm(50,mean=5,sd=1.5),Y=rnorm(50,mean=200,sd=25))

ui <-fluidPage(
  title = 'Download Plotly',
  sidebarLayout(

    sidebarPanel(
      helpText(),
      downloadButton('download'),
      tags$script('
                  document.getElementById("download").onclick = function() {
                  var plotly_svg = Plotly.Snapshot.toSVG(
                  document.querySelectorAll(".plotly")[0]
                  );

                  Shiny.onInputChange("plotly_svg", plotly_svg);
                  };
                  ')
      ),
    mainPanel(
      plotlyOutput('regPlot'),
      plotlyOutput('regPlot2')
    )
      )
)

server <- function(input, output, session) {

  output$regPlot <- renderPlotly({
    p <- plot_ly(d, x = d$X1, y = d$X2,mode = "markers")
    p
  })

  output$regPlot2 <- renderPlotly({
    p <- plot_ly(d, x = d$X1, y = d$X2,mode = "markers")
    p
  })

  observeEvent(input$plotly_svg, priority = 10, {
    png_gadget <- tempfile(fileext = ".png")
    png_gadget <- "out.png"
    print(png_gadget)
    rsvg_png(charToRaw(input$plotly_svg), png_gadget)
  })

  output$download <- downloadHandler(
    filename = function(){
      paste(paste("test",Sys.Date(),sep=""), ".png",sep="")},
    content = function(file) {
      temp_dir <- tempdir()
      tempImage <- file.path(temp_dir, 'out.png')
      file.copy('out.png', tempImage, overwrite = TRUE)
      png(file, width = 1200, height = 800, units = "px", pointsize = 12, bg = "white", res = NA)
      dev.off()
    })
}

shinyApp(ui = ui, server = server)

Additionally i am not sure how can i choose which of the plotly images should be downloaded. Thanks for any tips and help!

Info:

--> I have tried using webshot, however if I zoom or filter in any way plot, unfortunatelly webshot does not mirror it

--> i am not using the available plotly panel for download, because it is not working using IE

Answer 1

1) Install the webshot package.

2) Install phantom.js:

library(webshot)
install_phantomjs()

See ?install_phantomjs for the details.

3) Now you can use the export function of the plotly package:

library(shiny)
library(plotly)

d <- data.frame(X1 = rnorm(50,mean=50,sd=10), 
                X2 = rnorm(50,mean=5,sd=1.5), 
                Y = rnorm(50,mean=200,sd=25))

ui <-fluidPage(
  title = 'Download Plotly',
  sidebarLayout(

    sidebarPanel(
      helpText(),
      downloadButton('download')
    ),

    mainPanel(
      plotlyOutput('regPlot'),
      plotlyOutput('regPlot2')
    )
  )
)

server <- function(input, output, session) {

  regPlot <- reactive({
    plot_ly(d, x = d$X1, y = d$X2, mode = "markers")
  })
  output$regPlot <- renderPlotly({
    regPlot()
  })

  regPlot2 <- reactive({
    plot_ly(d, x = d$X1, y = d$X2, mode = "markers")
  })
  output$regPlot2 <- renderPlotly({
    regPlot2()
  })

  output$download <- downloadHandler(
    filename = function(){
      paste0(paste0("test", Sys.Date()), ".png")
    },
    content = function(file) {
      export(regPlot(), file=file)
    })
}

shinyApp(ui = ui, server = server)

You can save to the svg format. See ?export for the explanations.