问如何将更新后的列名从HandsOnTable传递到Shiny中的绘图？

EN

library(shiny)
library(rhandsontable)
library(dplyr)

#UI
ui <- shinyUI(fluidPage(
  titlePanel("Boxplot builder"),
   textOutput('result'),
     sidebarLayout(
        sidebarPanel(
            wellPanel(
               plotOutput("plot")),

            wellPanel(
               h3("Build BoxPlot"), 
                   actionButton("build", "Build")),   

            wellPanel(
               h3("Export Plot"),
                   downloadButton('ExportPlot', 'Export as png')), 
                         ),

            mainPanel(textInput("colnames", "Enter Column Names (separated by comma)", 
                  value="", placeholder = "e.g. Var1, Var2, etc"),
                  h5(tags$b("Enter data")),
                         rHandsontableOutput('table'))
                                  )))

rowNames <- c(sprintf("[%d]",seq(1:20)), "Means")
 defaultDF <- data.frame(
 row.names = rowNames,
 A = rep(NA_integer_, nrow=21),
 B = rep(NA_integer_, 21),
 C = rep(NA_integer_, 21),
  stringsAsFactors = FALSE)

#Server
server <- function(input, output, session)
 ({
  values <- reactiveValues(data = defaultDF) 

 observe({
  req(input$table)
  DF <- hot_to_r(input$table)
  DF[setdiff(rowNames, "Means"),]
  DF["Means",] <- colMeans(DF[setdiff(rowNames, "Means"),], na.rm = TRUE)
  values$data <- DF
})

output$table <- renderRHandsontable({
  req(values$data)
  rhandsontable(values$data, rowHeaderWidth = 100, 
  colHeaders=str_trim(unlist(strsplit(input$colnames,","))),) %>%
    hot_row(nrow(values$data), readOnly = TRUE)
}) 

observeEvent(input$build, {      
  output$plot <- renderPlot({
            boxplot(values$data)
          })
})    

 #Export PNG
  output$ExportPlot = downloadHandler(
  filename = 'BoxPlot.png',
  content = function(file) {        
      png(file) 
    boxplot(values$data) 
    dev.off()  
          })                                          
      })

shinyApp(ui = ui, server = server)