r - Get the size of the window in Shiny

Question

I Would like to determine the size of the browser window in Shiny to help me layout my plot divs better. Specifically I would like to determine the aspect ratio of the window to see how many divs I should spread across the screen and it still look nice. My initial thought would be that the number of plots would be floor(width/(height-navbar_height)).

I did some looking for this and I am currently unable to locate a possible solution and am currently lead to believe that this feature is simply not present in the clientData structure. Any thoughts?

Answer 1

See the example below. It uses Javascript to detect the browser window size (initial size and any resize), and use Shiny.onInputChange to send the data to the server code for processing. It uses shiny:connected event to get the initial window size, as Shiny.onInputChange is not ready for use until shiny is connected.

library(shiny)

# Define UI for application that draws a histogram
ui <- shinyUI(fluidPage(

   # Application title
   titlePanel("Old Faithful Geyser Data"),

   # Sidebar with a slider input for number of bins 
   sidebarLayout(
      sidebarPanel(
         tags$head(tags$script('
                                var dimension = [0, 0];
                                $(document).on("shiny:connected", function(e) {
                                    dimension[0] = window.innerWidth;
                                    dimension[1] = window.innerHeight;
                                    Shiny.onInputChange("dimension", dimension);
                                });
                                $(window).resize(function(e) {
                                    dimension[0] = window.innerWidth;
                                    dimension[1] = window.innerHeight;
                                    Shiny.onInputChange("dimension", dimension);
                                });
                            ')),
         sliderInput("bins",
                     "Number of bins:",
                     min = 1,
                     max = 50,
                     value = 30)
      ),

      # Show a plot of the generated distribution
      mainPanel(
         verbatimTextOutput("dimension_display"),
         plotOutput("distPlot")
      )
   )
))

# Define server logic required to draw a histogram
server <- shinyServer(function(input, output) {
   output$dimension_display <- renderText({
       paste(input$dimension[1], input$dimension[2], input$dimension[2]/input$dimension[1])
   })

   output$distPlot <- renderPlot({
      # generate bins based on input$bins from ui.R
      x    <- faithful[, 2] 
      bins <- seq(min(x), max(x), length.out = input$bins + 1)

      # draw the histogram with the specified number of bins
      hist(x, breaks = bins, col = 'darkgray', border = 'white')
   })
})

# Run the application 
shinyApp(ui = ui, server = server)