将使用leaflet.draw创建的功能保存到计算机

Question

我正在制作传单地图，我想使用leaflet.draw插件为用户提供绘制矢量和标记的选项。接下来，我想向用户提供将矢量/标记保存到他们的计算机的选项（例如，作为geojson）。我正在寻找指针和示例如何实现这一点。

Answer 1

如果你可以将所有功能都放到LayerGroup中，那么你可以在上面调用toGeoJSON() - 请参阅http://leafletjs.com/reference.html#layergroup-togeojson。然后可以将结果发送到FileSaver.js进行客户端下载，例如

var blob = new Blob([JSON.stringify(result)], {type: "application/json;charset=utf-8"});
saveAs(blob, "features.json");

Answer 2

editCoord <- function(){
  pgn <- NULL
  if(length(input$map_draw_all_features$features) != 0) {
    if(unique(unlist(lapply(input$map_draw_all_features$features, function(x){x$geometry$type}))) == "Polygon") {
      for(j in 1:length(input$map_draw_all_features$features)){
        geo <- unlist(lapply(input$map_draw_all_features$features[j], function(x){x$geometry$coordinates}))
        v <- seq(1, length(geo), 2)
        n <- length(geo)/2 
        for (i in 1:n) {  
          xy <- c(geo[v[i]], geo[i*2])
          if (i == n) break()
          pgn <- c(pgn, paste0(xy[1]," ",xy[2],","))
        }
        pgn <- c(pgn, paste0(xy[1]," ",xy[2]))
      }
      cat(pgn, "\n", file=paste0("f", input$usertext))
      readLines(paste0("f", input$usertext))
    }
  } 
}

editPlot <- function(){
  db <- dbConnect(MySQL(), dbname = "watsan", host = options()$rds$host, 
                  port = options()$rds$port, user = options()$rds$user, 
                  password = options()$rds$password)
  # Construct the update query
  query <- paste0('UPDATE plots SET `geom_plot`= ST_GeomFromText("POLYGON((',"",Coord(),"",'))") WHERE `parcel_id`=',"'",  ID() ,"'",';')
  query <- gsub('\"', "'", query)
  # Submit the fetch query and disconnect
  dbGetQuery(db, query)
  dbDisconnect(db)
}