Get output information — getCurrentOutputInfo

v1.7.0|Source: R/shiny.R

Description

Returns information about the currently executing output, including its name (i.e., outputId); and in some cases, relevant sizing and styling information.

getCurrentOutputInfo(session = getDefaultReactiveDomain())

Arguments

session

The current Shiny session.

Value

NULL if called outside of an output context; otherwise, a list which includes:

• The name of the output (reported for any output).

• If the output is a plotOutput() or imageOutput(), then:

  • height: a reactive expression which returns the height in pixels.

  • width: a reactive expression which returns the width in pixels.

• If the output is a plotOutput(), imageOutput(), or contains a shiny-report-theme class, then:

  • bg: a reactive expression which returns the background color.

  • fg: a reactive expression which returns the foreground color.

  • accent: a reactive expression which returns the hyperlink color.

  • font: a reactive expression which returns a list of font information, including:

    • families: a character vector containing the CSS font-family property.

    • size: a character string containing the CSS font-size property

Examples

if (interactive()) {
  shinyApp(
    fluidPage(
      tags$style(HTML("body {background-color: black; color: white; }")),
      tags$style(HTML("body a {color: purple}")),
      tags$style(HTML("#info {background-color: teal; color: orange; }")),
      plotOutput("p"),
      "Computed CSS styles for the output named info:",
      tagAppendAttributes(
        textOutput("info"),
        class = "shiny-report-theme"
      )
    ),
    function(input, output) {
      output$p <- renderPlot({
        info <- getCurrentOutputInfo()
        par(bg = info$bg(), fg = info$fg(), col.axis = info$fg(), col.main = info$fg())
        plot(1:10, col = info$accent(), pch = 19)
        title("A simple R plot that uses its CSS styling")
      })
      output$info <- renderText({
        info <- getCurrentOutputInfo()
        jsonlite::toJSON(
          list(
            bg = info$bg(),
            fg = info$fg(),
            accent = info$accent(),
            font = info$font()
          ),
          auto_unbox = TRUE
        )
      })
    }
  )
}