在R闪亮的传单弹出窗口中自动化图像大小

Question

我有一个闪亮的应用程序，我在R Studio的3个单独的标签中运行：

全局标签：

library(shiny)
library(leaflet)

country = c("Russia", "Mongolia", "China")
latitude = c(64.9, 47.01, 35.6)
longitude = c(91.2, 98.1, 95.6)
photo = c("russia.png", "mongolia.png", "china.png")
text = c("This is Russia", "This is Mongolia", "This is China")
countries = cbind.data.frame(country, latitude, longitude, photo, text)

ui tab：

ui = fluidPage(
  hr(),
  tags$p("Please click on the button to see the data:"), 
  actionButton(inputId = "go",
               label = "Button!", align = "center"),
  hr(), 
  leafletOutput("basicMap", height = "500px")
)

服务器标签：

server = function(input, output, session) {

  readData = eventReactive(input$go, {
    countries
  })


  output$basicMap = renderLeaflet({
    leaflet(data = readData()) %>%
      addTiles() %>%
      addCircleMarkers(data = readData(), lng = ~ longitude, lat = ~ latitude,

                       popup = ~ paste0("<strong>","", readData()$country, '</strong>',"<br>",
                                      "<br>", 
                                      "<img src = ", readData()$photo, ">",
                                      "<br>",
                                      "<strong>","", readData()$text, '</strong>',"<br>"
                       ))
    })
      }

这样运行正常，在每个弹出窗口中，我有一个标题和一些文本，它们对应于弹出该弹出窗口的数据框中的相关行。对于图像也是如此。但是，我无法自动化图像大小：

请有人帮我这样做吗？谢谢！