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Description

How to use the maxAllowableOffset FeatureLayer option to generalize features for display. This option is useful when you want to display a generalized version of the features for optimized display. For example, at small scales you may not need to display detail feature boundaries but as end-users zoom into larger scales you can display additional detail as needed. In this sample, the maximum allowable offset is calculated when the map is zoomed.

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>FeatureLayer: Changing MaxAllowableOffset (based on zoom level)</title>

  <link rel="stylesheet" href="https://js.arcgis.com/3.28/dijit/themes/claro/claro.css">
  <link rel="stylesheet" href="https://js.arcgis.com/3.28/esri/css/esri.css">
  <style>
      html, body { height: 100%; width: 100%; margin: 0; padding: 0; }
      #map {
        padding:0;
      }
      #status {
        background-color: black;
        color: white;
        padding: 3px;
        border: solid 1px white;
        -moz-border-radius: 5px;
        -webkit-border-radius: 5px;
      }
    </style>

    <script>var dojoConfig = {parseOnLoad: true};</script>
    <script src="https://js.arcgis.com/3.28/"></script>
    <script>
    dojo.require("dijit.layout.BorderContainer");
    dojo.require("dijit.layout.ContentPane");
    dojo.require("esri.map");
    dojo.require("esri.layers.FeatureLayer");
    dojo.require("dijit.form.CheckBox");

    var map, featureLayer;
    var featureLayerUrl = "https://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Petroleum/KSPetro/MapServer/1";

    function init() {
      map = new esri.Map("map", {
        basemap: "topo",
        center: [-99.5, 38.027],
        zoom: 7
      });

      map.on("load", mapLoaded);

      map.on("update-start", function(){
        esri.show(dojo.byId("status"));
      });

      map.on("update-end", function(){
        esri.hide(dojo.byId("status"));
      });
    }

    function mapLoaded() {
      featureLayer = new esri.layers.FeatureLayer(featureLayerUrl);

      featureLayer.on("update-start", function(){
        dojo.style(dojo.byId("status"), "display", "");
      });
      featureLayer.on("update-end", function(){
        dojo.style(dojo.byId("status"), "display", "none");
      });

      map.addLayers([featureLayer]);
    }

    function toggleLayer(val){
      if(val.name === 'checkBM'){
        var basemap = map.getLayer(map.layerIds[0]);
        basemap.visible ? basemap.hide(): basemap.show();
      } else {
        featureLayer.visible ? featureLayer.hide():featureLayer.show();
      }
    }

    dojo.ready(init);
  </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 data-dojo-type="dijit.layout.ContentPane" data-dojo-props="region:'right'" style="width:200px;">
     <p>
     Run the sample with Firebug's net panel open and notice that the maxAllowableOffset is different based on the zoom level.
     </p>

     <label for="checkBM">Basemap</label>
     <input data-dojo-type="dijit.form.CheckBox" checked="basemap.layer.visible" name="checkBM" onChange="toggleLayer(this);"/>
     <br />
     <label for="checkFL">Feature Layer</label>
     <input data-dojo-type="dijit.form.CheckBox" checked="featureLayer.layer.visible" name="checkFL" onChange="toggleLayer(this);"/>

    </div>
    <div id="map" data-dojo-type="dijit.layout.ContentPane" data-dojo-props="region:'center'" style="border:1px solid #000;padding:0;">
      <span id="status" style="position: absolute; z-index: 100; right: 5px; top: 5px;">
        Loading...
      </span>
    </div>
  </div>
</body>

</html>
 
          
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