add example with Shiny gadget for Leaflet.Draw; cc @tim-salabim

inst/examples/gadget_draw.R

@@ -0,0 +1,45 @@
+# start toward a Shiny gadget for Leaflet and Leaflet.Draw
+#   still missing many features but hopefully serves
+#   as proof of concept
+
+#' Leaflet Draw Shiny Gadget
+#'
+#' @param lf leaflet map currently with \code{addDrawToolbar} already
+#'             added.
+#' @param width,height valid \code{CSS} size for the gadget
+
+leafdraw_gadget <- function(lf = NULL, height = NULL, width = NULL) {
+  # modeled after chemdoodle gadget
+  #  https://github.com/zachcp/chemdoodle/blob/master/R/chemdoodle_sketcher_gadgets.R
+  stopifnot(requireNamespace("miniUI"), requireNamespace("shiny"))
+  ui <- miniUI::miniPage(
+    miniUI::miniContentPanel(lf, height=NULL, width=NULL),
+
+    miniUI::gadgetTitleBar("Draw Something", right = miniUI::miniTitleBarButton("done", "Done", primary = TRUE))
+  )
+
+  server <- function(input, output, session) {
+    shiny::observeEvent(input$done, { shiny::stopApp(input$undefined_draw_new_feature) })
+    shiny::observeEvent(input$cancel, { shiny::stopApp (NULL) })
+  }
+
+  shiny::runGadget(
+    ui,
+    server,
+    viewer =  shiny::dialogViewer("View and Edit Data"),
+    stopOnCancel = FALSE
+  )
+}
+
+
+# example use
+library(leaflet)
+library(leaflet.extras)
+library(mapview)
+
+lf <- mapview(breweries91)@map %>%
+  addTiles() %>%
+  addDrawToolbar()
+
+drawn <- leafdraw_gadget(lf)
+drawn