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BlendRenderer - Los Angeles housing status

Description

This sample displays housing status concentrations throughout the Greater Los Angeles area. Red indicating renter-occupied, green is vacant, whereas blue represents owner-occupied housing. The more opaque the color, the higher the concentration for that specific type of housing. More information on working with the BlendRenderer can be found here.

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>BlendRenderer: Los Angeles housing status</title>
    <link rel="stylesheet" href="https://js.arcgis.com/3.23/dijit/themes/claro/claro.css">
    <link rel="stylesheet" href="https://js.arcgis.com/3.23/esri/css/esri.css">
    <style>
      html, body, #map {
        height: 100%;
        margin: 0;
      }

      #meta {
        position: absolute;
        left: 20px;
        bottom: 20px;
        width: 20em;
        height: 16em;
        z-index: 40;
        background: #ffffff;
        color: #777777;
        padding: 5px;
        border: 2px solid #666666;
        -webkit-border-radius: 5px;
        -moz-border-radius: 5px;
        border-radius: 5px;
        font-family: arial;
        font-size: 0.9em;
      }

      #meta h3 {
        color: #666666;
        font-size: 1.1em;
        padding: 0px;
        margin: 0px;
        display: inline-block;
      }
    </style>
    <script src="https://js.arcgis.com/3.23/"></script>
    <script>
      require([
        "esri/Color", "esri/dijit/PopupTemplate", "esri/layers/FeatureLayer", "esri/map", "esri/renderers/BlendRenderer",
        "esri/symbols/SimpleFillSymbol", "esri/symbols/SimpleLineSymbol", "dojo/domReady!"
      ], function (Color, PopupTemplate, FeatureLayer, Map, BlendRenderer, SimpleFillSymbol, SimpleLineSymbol){

        map = new Map("map", {
          basemap: "topo", //"topo"
          center: [-118.40, 34.06],
          zoom: 12
        });

        //Set the blendRenderer's parameters
        var blendRendererParams = {
          //blendMode:"overlay" //By default, it uses "source-over", uncomment to display different mode
          //See: http://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/globalCompositeOperation
          symbol: new SimpleFillSymbol().setOutline(new SimpleLineSymbol().setWidth(0)),
          fields: [
            {
              field: "OWNER_CY",
              color: new Color([0, 0, 255])
            }, {
              field: "RENTER_CY",
              color: new Color([255, 0, 0])
            }, {
              field: "VACANT_CY",
              color: new Color([0, 255, 0])
            }
          ],
          opacityStops: [
            {
              value: .1,
              opacity: 0
            },
            {
              value: 1,
              opacity: .7
            }
          ],
          normalizationField: "TOTHU_CY"
        };

        //Create the PopupTemplate to be used to display demographic info
        var template = new PopupTemplate({
          "title": "Housing Status by Census Block",
          "fieldInfos": [
            {
              "fieldName": "OWNER_CY",
              "label": "Number of Owner Occupied Houses",
              "visible": true,
              "format": {
                "places": 0,
                "digitSeparator": true
              }
            }, {
              "fieldName": "RENTER_CY",
              "label": "Number of Renter Occupied Houses",
              "visible": true,
              "format": {
                "places": 0,
                "digitSeparator": true
              }
            }, {
              "fieldName": "VACANT_CY",
              "label": "Number of Vacant Houses",
              "visible": true,
              "format": {
                "places": 0,
                "digitSeparator": true
              }
            }, {
              "fieldName": "TOTHU_CY",
              "label": "Total Housing Units",
              "visible": true,
              "format": {
                "places": 0,
                "digitSeparator": true
              }
            }
          ]
        });

        var layerUrl = "https://services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/Blocks%20near%20Wilshire%20enriched%20with%20Key%20Facts/FeatureServer/0";

        var renderer = new BlendRenderer(blendRendererParams);

        layer = new FeatureLayer(layerUrl, {
          id: "blendedLayer",
          outFields: ["TOTHU_CY", "RENTER_CY", "OWNER_CY", "VACANT_CY"],
          opacity: 1,
          definitionExpression: "TOTHU_CY > 0",
          infoTemplate: template
        });

        layer.setRenderer(renderer);
        map.addLayer(layer);

      });
    </script>
  </head>

  <body class="claro">
    <div data-dojo-type="dijit/layout/BorderContainer" data-dojo-props="design:'headline',gutters:false" style="width: 100%; height: 100%; margin: 0;">
      <div id="map" data-dojo-type="dijit/layout/ContentPane" data-dojo-props="region:'center'">
         <div id="meta">
            <h3>Los Angeles housing status displayed using a BlendRenderer</h3>
            <br>
            <br>This sample displays housing status concentrations throughout the Greater Los Angeles area.
            <ul>
               <li>Red: Renter occupied</li>
               <li>Blue: Owner occupied</li>
               <li>Green: Vacant</li>
            </ul>
            The more opaque the color, the higher the concentration for that housing status.
         </div>
      </div>
    </div>
  </body>
</html>