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Display more data with FeatureLayer

Description

This sample demonstrates how to enable WebGL rendering on a FeatureLayer. WebGL allows you to display more features in the view and update the renderer of the layer more rapidly.

Code

<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
  <title>Render FeatureLayer with WebGL</title>

  <link rel="stylesheet" href="https://js.arcgis.com/3.25/dijit/themes/claro/claro.css">
  <link rel="stylesheet" href="https://js.arcgis.com/3.25/esri/css/esri.css">

  <style>
    html, body, #mapDiv{
      padding:0;
      margin:0;
      height:100%;
      width: 100%;
    }
    #infoDiv {
      height: 320px;
      z-index: 2;
      padding: 10px;
      width: 250px;
      background-color: white;
      position: absolute;
      left: 20px;
      bottom: 20px;
      font-family: Verdana, Helvetica, sans-serif;
      font-size: 16px;
      color: #444;
      text-align: center;
    }
  </style>

  <script>
    // Enable WebGL on FeatureLayer for faster renderer updates and
    // display of more features in the map
    var dojoConfig = {
      has: {
        "esri-featurelayer-webgl": 1
      }
    }
  </script>

  <script src="https://js.arcgis.com/3.25/"></script>

  <script>
    require([
      "esri/map",
      "esri/urlUtils",
      "esri/arcgis/utils",
      "esri/dijit/ColorInfoSlider",
      "dojo/domReady!"
    ], function(
      Map,
      urlUtils,
      arcgisUtils,
      ColorInfoSlider
    ) {

      // if accessing webmap from a portal outside of ArcGIS Online, uncomment and replace path with portal URL
      // arcgisUtils.arcgisUrl = "https://pathto/portal/sharing/content/items";

      arcgisUtils.createMap("a5b3d1196239447a880f3e47e5ed467a", "mapDiv").then(function (response) {

        var map = response.map;
        var zipCodeLayerId = map.graphicsLayerIds[0];
        var zipCodeLayer = map.getLayer(zipCodeLayerId);

        var renderer = zipCodeLayer.renderer;
        var authoringColorInfo = renderer.authoringInfo.visualVariables[0];
        var colorVisualVariable = renderer.visualVariables.filter(function(vv){
          return vv.type === authoringColorInfo.type;
        })[0];

        document.getElementById("title").innerHTML = colorVisualVariable.valueExpressionTitle;

        var sliderMin = 40;  // statistical min is 0, but 40 allows us to zoom to the histogram
        var sliderMax = authoringColorInfo.maxSliderValue

        zipCodeLayer
          .addPlugin("esri/plugins/FeatureLayerStatistics")
          .then(function(){
            zipCodeLayer
            .statisticsPlugin
            .getHistogram({
              valueExpression: colorVisualVariable.valueExpression,
              // querying with matching SQL expression gets histogram for full dataset
              sqlExpression: "( ACSNRETINC / (ACSNRETINC + ACSRETINC) ) * 100",
              sqlWhere: "ACSNRETINC + ACSRETINC > 0",  // avoid dividing by 0
              numBins: 30,
              minValue: sliderMin,
              maxValue: sliderMax
            })
            .then(function(histogram){

              var colorInfoSlider = new ColorInfoSlider({
                colorInfo: colorVisualVariable,
                minValue: sliderMin,
                maxValue: sliderMax,
                histogram: histogram,
                handles: [ 0,2,4 ],
                primaryHandle: 2
              }, "colorSliderElement");
              colorInfoSlider.startup();

              // reset renderer for each slider change
              colorInfoSlider.on("data-change", function(event){
                zipCodeLayer.renderer.setVisualVariables([event.colorInfo]);
                zipCodeLayer.redraw();
              });

            });
          });
      });

    });
  </script>
</head>

<body class="claro">
  <div id="mapDiv"></div>
  <div id="infoDiv">
      <span id="title"></span>
      <div id="colorSliderElement"></div>
  </div>
</body>

</html>
 
          
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