R传单正在覆盖层之上绘制基础层答案

【问题标题】：R leaflet is drawing base layers on top of overlay layersR传单正在覆盖层之上绘制基础层
【发布时间】：2018-02-16 18:54:37
【问题描述】：

我遇到了 R 传单的问题：当我更改基础层（多边形）时，覆盖层被推到基础层后面。根据我对 LeafletR 帮助文件的阅读，覆盖层的 z-index 应该始终高于基础层，并且应该保持在顶部。

示例在这里：http://rpubs.com/bvila/overdraw

require(acs)
require(tigris)
require(leaflet)
require(tidyverse)

leaflet(data = counties(state = "UT")) %>% 
  addPolygons(color = "red", fillColor = "orange", group = "base1", fillOpacity = 1) %>% 
  addPolygons(color = "pink", fillColor = "purple", group = "base2", fillOpacity = 1) %>% 
  addPolygons(color = "yellow", fillColor = "green", group = "overlay", fillOpacity = 1) %>% 
  addLayersControl(baseGroups = c("base1", "base2"), options = layersControlOptions(collapsed = F), overlayGroups = "overlay")

【问题讨论】：

标签： r leaflet r-leaflet

【解决方案1】：

多边形图层的 z-index 应始终高于平铺图层。图层控件使用此术语，因为基础组旨在成为基础（平铺）图层，而叠加组旨在成为叠加（多边形）图层。

您可以使用一点 JavaScript 来解决这个问题，查看添加到管道的 onRender 阶段（您只需为给定的地图对象执行一次）：

leaflet(data = counties(state = "UT")) %>% 
  addPolygons(color = "red", fillColor = "orange", group = "base1", fillOpacity = 1) %>% 
  addPolygons(color = "pink", fillColor = "purple", group = "base2", fillOpacity = 1) %>% 
  addPolygons(color = "yellow", fillColor = "green", group = "overlay", fillOpacity = 0.5) %>% 
  addLayersControl(baseGroups = c("base1", "base2"), options = layersControlOptions(collapsed = F), overlayGroups = "overlay") %>%
  htmlwidgets::onRender("
    function(el, x) {
      this.on('baselayerchange', function(e) {
        e.layer.bringToBack();
      })
    }
  ")

【讨论】：