4

我尝试使用来自Using任意 Leaflet JS plugins with Leaflet for R 的示例代码来实现 Leaflet-side-by-side 插件。看起来很简单，到目前为止还没有成功。我无法弄清楚我做错了什么。非常感谢您的回复。谢谢，

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


LeafletSideBySidePlugin <- htmlDependency("leaflet-side-by-side","2.0.0",
                                          src = c(href="https://github.com/digidem/leaflet-side-by-side"),
                                          script="leaflet-side-by-side.js")

# A function that takes a plugin htmlDependency object and adds
# it to the map. This ensures that however or whenever the map
# gets rendered, the plugin will be loaded into the browser.

registerPlugin <- function(map, plugin) {
   map$dependencies <- c(map$dependencies, list(plugin))
   map
}

leaflet() %>% addTiles() %>%
   setView(lng = 12, lat = 50, zoom = 4) %>%
   # Register leaflet-side-by-side plugin on this map instance
   registerPlugin(LeafletSideBySidePlugin) %>%
   onRender("
            function(el, x) {
var mylayer1 = L.tileLayer(
          'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',{
            maxZoom: 18
            })
var mylayer2 = L.tileLayer(
          '//stamen-tiles-{s}.a.ssl.fastly.net/watercolor/{z}/{x}/{y}.png',{
            maxZoom: 14
            })
            L.control.sideBySide(mylayer1, mylayer2).addTo(this);
            ")
4

2 回答 2

1

只是偶然发现了这个问题。

我认为您错过了每个瓦片地图图层的 addTo() 方法。这里应该是。

leaflet() %>% addTiles() %>%
   setView(lng = 12, lat = 50, zoom = 4) %>%
   # Register leaflet-side-by-side plugin on this map instance
   registerPlugin(LeafletSideBySidePlugin) %>%
   onRender("
        function(el, x) {
          var mylayer1 = L.tileLayer(
            'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',{
             maxZoom: 18
             }).addTo(this);
          var mylayer2 = L.tileLayer(
             '//stamen-tiles-{s}.a.ssl.fastly.net/watercolor/{z}/{x}/{y}.png',{
             maxZoom: 14
             }).addTo(this);
        L.control.sideBySide(mylayer1, mylayer2).addTo(this);
        ")
于 2017-08-22T14:12:04.453 回答
1

我要赞扬 Abuw 的回答。如果有人想知道为什么它仍然不起作用，那是因为 onRender JavaScript 中有一个不匹配的“{”。

还要确保您的 htmlDependency 源确实存在。 jsdelivr以 application/javascript 格式提供大多数可通过 npm 和 github 获得的 js 库。使用它而不是原始 github 路径，完整的工作代码应如下所示：

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


LeafletSideBySidePlugin <- htmlDependency("leaflet-side-by-side","2.0.0",
                                          src = c(href="https://cdn.jsdelivr.net/gh/digidem/leaflet-side-by-side@2.0.0/"),
                                          script="leaflet-side-by-side.js")

# A function that takes a plugin htmlDependency object and adds
# it to the map. This ensures that however or whenever the map
# gets rendered, the plugin will be loaded into the browser.

registerPlugin <- function(map, plugin) {
  map$dependencies <- c(map$dependencies, list(plugin))
  map
}

leaflet() %>% addTiles() %>%
  setView(lng = 12, lat = 50, zoom = 4) %>%
  # Register leaflet-side-by-side plugin on this map instance
  registerPlugin(LeafletSideBySidePlugin) %>%
  onRender("
        function(el, x) {
          var mylayer1 = L.tileLayer(
            'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',{
             maxZoom: 18
             }).addTo(this);
          var mylayer2 = L.tileLayer(
          '//stamen-tiles-{s}.a.ssl.fastly.net/watercolor/{z}/{x}/{y}.png',{
             maxZoom: 14
             }).addTo(this);
        L.control.sideBySide(mylayer1, mylayer2).addTo(this);
        }")
于 2020-04-22T15:23:07.367 回答