Add a shape to the map as a drawn shape object

Usage

add_drawn_shape(proxy, new_geometry)

Arguments

proxy: The map proxy object created by mapProxy().
new_geometry: The geometry for the new shape, provided as an sf object, GeoJSON string, or list that can be converted to GeoJSON.

Value

The map proxy object for chaining.

Examples

library(shiny)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(sf)
library(toro)

get_polygon <- function() {
  random_offset <- runif(1, -10, 10)
  sf::st_sf(
    geometry = sf::st_sfc(
      sf::st_polygon(list(matrix(
        c(
          174.7,
          -36.8,
          174.8,
          -36.8,
          174.8,
          -36.9,
          174.7,
          -36.9,
          174.7,
          -36.8
        ) +
          random_offset,
        ncol = 2,
        byrow = TRUE
      ))),
      crs = 4326
    )
  )
}

ui <- bootstrapPage(
  tagList(
    mapOutput("map"),
    actionButton("add", "Add shape"),
    actionButton("update", "Update shape"),
    actionButton("delete", "Delete shape"),
    h2("Selected shape ID"),
    textOutput("selected_shape")
  )
)

server <- function(
  input,
  output,
  session
) {
  selected_shape_id <- reactiveVal(NULL)

  output$map <- renderMap({
    map() |>
      add_draw_control(
        modes = c("polygon", "line", "delete"),
        features = get_polygon()
      )
  })

  output$selected_shape <- renderText({
    selected_shape_id()
  })

  observe({
    print(input$map_feature_click)
    selected_shape_id(input$map_feature_click$properties$id)
  }) |>
    bindEvent(input$map_feature_click)

  observe({
    add_drawn_shape(mapProxy("map"), get_polygon())
    selected_shape_id(NULL)
  }) |>
    bindEvent(input$add)

  observe({
    req(selected_shape_id())
    update_drawn_shape(mapProxy("map"), selected_shape_id(), get_polygon())
  }) |>
    bindEvent(input$update)

  observe({
    req(selected_shape_id())
    delete_drawn_shape(mapProxy("map"), selected_shape_id())
    selected_shape_id(NULL)
  }) |>
    bindEvent(input$delete)
}

if (interactive()) {
  shinyApp(ui, server)
}