将Leaflet Deflate与Shiny集成

如何解决将Leaflet Deflate与Shiny集成

已更新

找到this后，我对问题进行了一些调整。我已经成功加载并使用L.deflate创建了“缩小的功能”。但是现在，我需要以某种方式从地图中获取对象，然后将它们添加到deflate对象中，如leaflet.deflate文档中所述。

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我正在尝试使用步骤here将leaflet deflate plugin集成到Shiny应用程序中。我已经加载了插件，但是现在我只想知道如何从“多边形”层中获取对象并将其添加到文档中所述的delate_features对象中。

文档步骤

const map = L.map("map").setView([51.505,-0.09],12);

const deflate_features = L.deflate({minSize: 20});
deflate_features.addTo(map);

// This is the step I am not sure how to handle in the onRender()
const polygon = L.polygon([
    [51.509,-0.08],[51.503,-0.06],[51.51,-0.047]
]);
polygon.addTo(deflate_features);

测试应用

library(sf)
library(leaflet)
library(htmltools)
library(htmlwidgets)

js_file <- "https://unpkg.com/Leaflet.Deflate@1.3.0/dist/L.Deflate.js"


ui <- fixedPage(
  tags$head(tags$script(src = js_file)),leafletoutput("map")
)

server <- function(session,input,output) {
  
  output$map <- renderLeaflet({
    nc <- sf::st_read(system.file("shape/nc.shp",package = "sf"),quiet = TRUE)
    
    leaflet(options = leafletoptions(preferCanvas = TRUE)) %>% 
      addMapPane(name = "labels",zIndex = 650) %>% 
      addProviderTiles(providers$Stamen.TonerLabels,options = providerTileOptions(opacity = 0.35,updateWhenZooming = FALSE,pane = "labels")) %>% 
      addProviderTiles(providers$Stamen.TonerBackground,updateWhenZooming = FALSE)) %>% 
      addpolygons(data = st_transform(nc,4326)) %>% 
      onRender("function(el,x,data) {
               const deflate_features = L.deflate({ minSize: 20 });
               deflate_features.addTo(this);
               // How to select the polygons I already have and add them                       
               // to deflate_features????
      }")
    
  })
}
  
shinyApp(ui,server)