使用R中的addDrawToolbar在传单地图上绘制额外的标记

Question

我在传单地图上添加了一个工具栏,以便非编码人员可以轻松绘制标记.为此,我使用了以下R包:leaflet,leaflet.extras和shiny.

我有一些问题:

1)我添加了markerOptions(见下文)来定义红叶的图标.据我所知,你只能有一个选择.我的意思是没有办法让非编码人员从你定义的几个图标中选择与我一样的方式.是否有可能以其他方式实现？

2)单击左下方的STYLE EDITOR编辑叶子图标(见下图)后,它会切换回它本身具有的图标池,并且您要编辑的叶子图标将变为此池中的第一个图标.

实际上,如果有一种方法可以在右边的下面这个池中添加额外的图标,那么我的第一个问题就会得到解决.解决方案并不一定要在R中.

library(shiny)
library(leaflet)
library(leaflet.extras)


ui = fluidPage(
   tags$style(type = "text/css", "#map {height: calc(100vh - 20px)!important;}"),
   leafletOutput("map")
)

server = function(input,output,session){
   output$map = renderLeaflet(
   leaflet()%>%

   addTiles(urlTemplate = "http://mt0.google.com/vt/lyrs=m&hl=en&x={x}&y={y}&z={z}&s=Ga")%>%

   addMeasure(
    primaryLengthUnit = "kilometers",
    secondaryAreaUnit = FALSE
    )%>%

   addDrawToolbar(
    targetGroup='draw',
    editOptions = editToolbarOptions(selectedPathOptions = selectedPathOptions()),

    markerOptions = filterNULL(list(markerIcon = makeIcon(iconUrl = "http://leafletjs.com/examples/custom-icons/leaf-red.png")))) %>%
  setView(lat = 45, lng = 9, zoom = 3) %>% 

  addStyleEditor(position = "bottomleft", 
                 openOnLeafletDraw = TRUE)
  )
}

shinyApp(ui,server)

Answer 1

您可以通过以下方式在选择的 HTML 标签中列出一堆可能的图标（这里我选择 font-awesome）：

1) 获取字体很棒的图标的完整列表

fa_list <- read_html("http://astronautweb.co/snippet/font-awesome/") %>% 
  html_nodes("span.icon-name") %>% 
  html_text()
fa_pretty <- gsub("^fa-", "", fa_list)

2) 在你的 中ui，加载 font-awesome 字体

tags$head(
  tags$link(rel = "stylesheet", href = "https://maxcdn.bootstrapcdn.com/font-awesome/4.6.1/css/font-awesome.min.css")
)

3) 制作一个可以显示图标选择的 UI 小部件

shinyWidgets::pickerInput("defaultIcon", "Default Marker", choices = fa_pretty, 
                          options = pickerOptions(liveSearch = TRUE),
                          choicesOpt = list(icon = paste("fa", fa_list), 
                                            iconBase = "fontawesome"))

用户可以选择他/她想要的图标，并且您的工具栏可以通过编写以下内容来尊重它：

... %>% 
  addDrawToolbar(...,
    markerOptions = list(markerIcon = makeAwesomeIcon(icon = input$defaultIcon, library = "fa"))

但是，addDrawToolbar似乎不太适合leafletProxy，因此如果您更改 UI 中的标记图标，它将擦除传单地图，您必须从头开始。相反，如果您想切换图标并保留现有标记，您可以定义自己的功能来添加标记。在我看来，这是一个更灵活的解决方案，仍然可以处理您的所有 UI 和功能请求。完整示例如下：

library(shiny)
library(leaflet)
library(leaflet.extras)
library(rvest)

fa_list <- read_html("http://astronautweb.co/snippet/font-awesome/") %>% 
  html_nodes("span.icon-name") %>% 
  html_text()
fa_pretty <- gsub("^fa-", "", fa_list)
# Awesome-icon markers only support the colors below...
fa_cols <- c("red", "darkred", "lightred", "orange", "beige", "green", "darkgreen", 
             "lightgreen", "blue", "darkblue", "lightblue", "purple", "darkpurple", 
             "pink", "cadetblue", "white", "gray", "lightgray", "black")

ui <- fluidPage(
  tags$head(
    tags$link(rel = "stylesheet",
      href = "https://maxcdn.bootstrapcdn.com/font-awesome/4.6.1/css/font-awesome.min.css")
  ),
  tags$style(type = "text/css", "#map {height: calc(100vh - 20px)!important;}"),
  fluidRow(
    splitLayout(cellArgs = list(style = "overflow: visible;"),
      shinyWidgets::pickerInput("defaultIcon", "Default Marker", choices = fa_pretty, 
                                options = shinyWidgets::pickerOptions(liveSearch = TRUE),
                                choicesOpt = list(icon = paste("fa", fa_list), 
                                                  iconBase = "fontawesome")),
      colourpicker::colourInput("defaultColor", "Default icon color"),
      colourpicker::colourInput("defaultBg", "Default marker color", palette = "limited", 
                                allowedCols = fa_cols, returnName = TRUE, value = "red")
    ),
    tags$div( tags$b("Place Marker"), 
              shinyWidgets::switchInput("edit_mode", "Edit Mode", 
                                        onLabel = "Click on the map to add a marker"))
  ),
  leafletOutput("map")
)

server <- function(input,output,session){
  react_list <- reactiveValues()
  # While the user has toggled the edit-mode input, register any future map-clicks
  # as reactive values.
  observe({
    if (input$edit_mode & !isTRUE(input$map_click$.nonce == react_list$nonce)) {
      react_list$mapEditClick <- input$map_click
    }
    react_list$nonce <- input$map_click$.nonce
  })

  output$map <- renderLeaflet(
    leaflet() %>%
      addProviderTiles(providers$CartoDB.Positron) %>% 
      addMeasure(
        primaryLengthUnit = "kilometers",
        secondaryAreaUnit = FALSE) %>%
      setView(lat = 45, lng = 9, zoom = 3)
  )
  # When a user clicks on the map while being in edit-mode, place a marker with
  # the chosen icon, color and marker-color at the click coordinates.
  observeEvent(react_list$mapEditClick, {
    leafletProxy("map") %>% 
      addAwesomeMarkers(
        lng     = react_list$mapEditClick$lng, 
        lat     = react_list$mapEditClick$lat,
        layerId = as.character(react_list$mapEditClick$.nonce),
        icon    = makeAwesomeIcon(icon     = input$defaultIcon, 
                               library     = "fa", 
                               iconColor   = input$defaultColor, 
                               markerColor = input$defaultBg),
        label = "Click to delete", 
        labelOptions = labelOptions(TRUE))
  })
  # Delete the marker when it has been clicked.
  observeEvent(input$map_marker_click, {
    leafletProxy("map") %>%
      removeMarker(as.character(input$map_marker_click$id))
  })
}

shinyApp(ui,server)