How to update polyline/polygon color without re-render

[courtwarr]

I'm working on a shiny app that render 30-100k polylines and leafgl blows standard leaflet out of the water on render time. However, this map is intended to be interactive, and I'd like to be able to update the colors via leafletProxy without re-rendering the map.

There's no feature of this sort in vanilla leaflet but there is a workaround in a proposed commit covered here (rstudio/leaflet#496) and here (rstudio/leaflet#598) that works well. Rendering all my shapes is very slow the first time, but then simply updating the colors using this method is very fast. I'd love to to be able to update the color of my shapes using leafgl instead. Working reprex below.

library(shiny)
library(sf)
library(leaflet)
library(leafgl)

data <- gadmCHE %>%
  as("SpatialLinesDataFrame") %>%
  st_as_sf() %>%
  st_cast("LINESTRING")

setShapeStyle <- function( map, data = getMapData(map), layerId,
                           stroke = NULL, color = NULL,
                           weight = NULL, opacity = NULL,
                           fill = NULL, fillColor = NULL,
                           fillOpacity = NULL, dashArray = NULL,
                           smoothFactor = NULL, noClip = NULL,
                           options = NULL
){
  options <- c(list(layerId = layerId),
               options,
               filterNULL(list(stroke = stroke, color = color,
                               weight = weight, opacity = opacity,
                               fill = fill, fillColor = fillColor,
                               fillOpacity = fillOpacity, dashArray = dashArray,
                               smoothFactor = smoothFactor, noClip = noClip
               )))
  
  options <- evalFormula(options, data = data)
  
  options <- do.call(data.frame, c(options, list(stringsAsFactors=FALSE)))
  
  layerId <- options[[1]]
  style <- options[-1]
  
  leaflet::invokeMethod(map, data, "setStyle", "shape", layerId, style);
}

ui <- fluidPage(
  tags$head(
    tags$script(HTML(
      '
window.LeafletWidget.methods.setStyle = function(category, layerId, style){
  var map = this;
  if (!layerId){
    return;
  } else if (!(typeof(layerId) === "object" && layerId.length)){ // in case a single layerid is given
    layerId = [layerId];
  }

  //convert columnstore to row store
  style = HTMLWidgets.dataframeToD3(style);
  //console.log(style);

  layerId.forEach(function(d,i){
    var layer = map.layerManager.getLayer(category, d);
    if (layer){ // or should this raise an error?
      layer.setStyle(style[i]);
    }
  });
};
'
    ))
  ),
  fluidRow(
    column(width=6,offset=0,leafletOutput("map")),
    column(width=6,offset=0,leafletOutput("glMap"))
  ),
  radioButtons("color", "Color", choices = c("blue", "red"))
)

server <- function(input, output, session){
  output$map <- renderLeaflet({
    leaflet(data) %>%
      addPolylines(data=data,layerId = as.character(1:nrow(data)))
  })
  
  output$glMap <- renderLeaflet({
    leaflet(data) %>%
      addGlPolylines(data=data,layerId = as.character(1:nrow(data)))
  })
  
  observe({
    leafletProxy("map", data = data) %>%
      setShapeStyle(layerId = as.character(1:nrow(data)), color = input$color)
  })
  
  observe({
    leafletProxy("glMap", data = data) %>%
      setShapeStyle(layerId = as.character(1:nrow(data)), color = input$color)
  })
  
}

shinyApp(ui, server)

[tim-salabim]

I don't think that's possible. WebGl is not svg and I am not sure if one can update style attributes or if they even exist in webgl... That question would be best asked in the upstream repo, because that's where it needs to be implemented to be available here.