Smoothly transition renderPlot shiny R

Question

I have done an animation in Shiny using this approach The problem I find is that the transition from plot to plot gets a bit stuck (The plot area fades off while processing the next plot).

I would like to keep the prior plot until the next is ready. Is there a way to transition from the one renderPlot to the next one avoiding the fade off effect on the prior plot?

Below I include a minimal working example. If your computer does not get stuck just increase the K and it eventually will.

library(shiny)
library(ggplot2)
k<-50000L
data=data.frame(x=runif(k),y=runif(k))

runApp(list(
  ui =fluidPage(
    tags$head(tags$style(".rightAlign{float:right;}")),
    headerPanel("Cost Explorer"),

    sidebarPanel(
      actionButton("goButton", "Go!"),
      actionButton("reset", "Reset")  ),
      mainPanel(fluidRow(column(8,
      plotOutput(outputId="tsplot"),class = 'rightAlign')))),

  server=function(input, output, session) {

  datareactive<-reactiveValues(data=data)
  t <- reactiveValues(counter=1)

  observe({
    isolate({   
      t$counter=t$counter+1;
      datareactive$data<-data.frame(x=runif(k),y=runif(k))
    })
      if ((input$goButton > 0)){
        invalidateLater(200, session)
      }



  })

    output$tsplot <- renderPlot({
      ggplot(datareactive$data,aes(x,y))+geom_point()+coord_fixed()+
      theme_bw()+
      geom_path(data=datareactive$data[(k-10):k,],aes(x,y),size=1.1,
                colour="blue")+
      geom_point(data=datareactive$data[k,],aes(x,y),
                   colour="red")
    })

  }
))

Answer 1

You can do this by using the shinycssloaders package in your shiny UI, like this:

plotOutput("tsplot") %>% shinycssloaders::withSpinner(hide.ui = FALSE)

Using the argument hide.ui will avoid the fading of the plot while its being loaded.