Capture Screenshot as Image — capture • capture

Add a button to take a screenshot of a specified element and download a PNG file.

Usage

capture(
  selector,
  filename,
  ...,
  format = c("png", "jpeg"),
  scale = NULL,
  inputId = NULL,
  options = NULL,
  loading = NULL,
  statusInputId = NULL,
  button_class = "btn btn-default"
)

Arguments

selector: A CSS selector, for example body to target the whole page or #<ID> to target a specific output.
filename: Name of the file (without extension) that will be created. If NULL no file is downloaded client side.
...: Arguments passed to HTML button.
format: Format of output between: "png" or "jpeg".
scale: Scale factor applied to image's dimension. Can be used to get a higher resolution image.
inputId: An inputId to retrieve image as base64 in an input slot server-side.
options: Options (as a list) passed to html-to-image method, for example you can use backgroundColor to set background color.
loading: Add a loading indicator if taking screenshot take time, see loading() for usage.
statusInputId: Retrieve status information in an input value server-side with following structure: list(status = "started|finished|error", timestamp = <POSIX timestamp>).
button_class: Class to use for the HTML tag <button>

Value

an HTML tag that can be used in UI or rmarkdown HTML document.

Note

It's only possible to take screenshot of elements that are actually visible on screen. It doesn't work in Internet Explorer.

Examples

library(shiny)
library(capture)

ui <- fluidPage(
  tags$h2("Capture example"),
  capture(
    selector = "body",
    filename = "all-page",
    icon("camera"), "Take screenshot of all page",
    format = "png"
  ),
  tags$br(),
  fluidRow(
    column(
      width = 4,
      wellPanel(
        tags$b("Parameters :"),
        selectInput(
          inputId = "loi",
          label = "Law:",
          choices = c("normal", "uniform", "exponential")
        )
      )
    ),
    column(
      width = 8,
      tags$div(
        id = "result-block",
        tags$b("Results :"),
        plotOutput(outputId = "plot"),
        uiOutput(outputId = "mean"),
        verbatimTextOutput(outputId = "raw")
      ),
      capture(
        selector = "#result-block",
        filename = "results-screenshot",
        icon("camera"), "Take screenshot of results",
        options = list(backgroundColor = "#FFF")
      ),
      capture(
        selector = "#result-block",
        filename = "results-screenshot",
        icon("camera"), "Take screenshot of results (bigger scale)",
        scale = 3,
        options = list(backgroundColor = "#FFF")
      ),
      capture(
        selector = "#result-block",
        filename = NULL, # no download client side
        icon("camera"), "Take screenshot of results (retrieve server side)",
        inputId = "screenshot",
        options = list(backgroundColor = "#FFF")
      ),
      uiOutput("out")
    )
  )
)

server <- function(input, output, session) {
  
  output$out <- renderUI({
    # # Here we display image back in interface, 
    # # but you can also write image on disk
    # write_png <- function(x, filename) {
    #   x <- sub(".*,", "", x)
    #   x <- base64enc::base64decode(x)
    #   png::writePNG(png::readPNG(x), filename)
    # }
    # write_png(input$screenshot, "myimage.png")
    
    tags$img(src = input$screenshot)
  })
  
  
  distrib_r <- reactive({
    switch(
      input$loi,
      "normal" = rnorm(1000),
      "uniform" = runif(1000),
      "exponential" = rexp(1000)
    )
  })

  output$plot <- renderPlot({
    hist(distrib_r())
  })

  output$mean <- renderUI({
    tags$p(tags$b("The mean is :"), round(mean(distrib_r()), 2))
  })

  output$raw <- renderPrint({
    summary(distrib_r())
  })
}

if (interactive())
  shinyApp(ui, server)