Example of changing the font size on a labelLayer based on scale

TracySchloss · ‎09-28-2015

Does anyone have a sample of using the current map scale to change the font size on a labelLayer? All my maps are state-wide, which requires a small font size. Once you zoom in a bit, the font ends up too small.

I can envision how to do this, but I hoped that someone already had some code written that they were satisfied with the results.

TracySchloss · ‎09-29-2015

I'm surprised there was no one who has played with this, but I couldn't find very many examples at all with scaleDependentRenderers, especially for labelLayer. It took some fiddling, but I came up with something that was satisfactory for my purposes. Hopefully this will benefit someone else.

<!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></title>
    <link rel="stylesheet" href="https://community.esri.com//js.arcgis.com/3.14/esri/css/esri.css">
    <style type="text/css">
      html, body, #map {
        height: 100%; width: 100%; margin: 0; padding: 0;
      }
    </style>

    <script type="text/javascript" src="//js.arcgis.com/3.14/"></script>
    <script type="text/javascript" >
      var map;
   
      require([
      "dojo/on",
      "dojo/dom",
        "esri/map",
        "esri/dijit/Scalebar",
        "esri/geometry/Extent",
        "esri/SpatialReference",
        "esri/layers/FeatureLayer",

        "esri/symbols/SimpleLineSymbol",
        "esri/symbols/SimpleFillSymbol", 
        "esri/symbols/TextSymbol",
        "esri/renderers/SimpleRenderer",
        "esri/renderers/ScaleDependentRenderer",
        "esri/layers/LabelLayer",

        "esri/Color",
        "dojo/domReady!"
      ], function(
        on,dom,Map, Scalebar,Extent,SpatialReference, FeatureLayer,
        SimpleLineSymbol, SimpleFillSymbol, TextSymbol, SimpleRenderer,ScaleDependentRenderer,
        LabelLayer,
        Color
      ) {

        map = new Map("map", {
      center: [-92.593, 38.5],
        zoom: 7,
        basemap:'gray'
        });
        
        var labelField = "STATE_NAME";

        // create a renderer for the states layer to override default symbology
        var statesColor = new Color("#666");
        var statesLine = new SimpleLineSymbol("solid", statesColor, 1.5);
        var statesSymbol = new SimpleFillSymbol("solid", statesLine, null);
        var statesRenderer = new SimpleRenderer(statesSymbol);
        // create a feature layer to show country boundaries
        var statesUrl = "http://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3";
        var states = new FeatureLayer(statesUrl, {
          id: "states",
          outFields: [labelField]
        });
        states.setRenderer(statesRenderer);
        map.addLayer(states);
   
        // create a text symbol to define the style of labels
        var statesLabel = new TextSymbol().setColor(statesColor);
        statesLabel.font.setSize("14pt");
        statesLabel.font.setFamily("arial");
        var statesLabelRenderer = new SimpleRenderer(statesLabel);
        var labels = new LabelLayer({
          id: "labels"
        });
        // tell the label layer to label the states feature layer
        // using the field named "STATE_NAME"
        labels.addFeatureLayer(states, statesLabelRenderer, "{" + labelField + "}");
        // add the label layer to the map
        map.addLayer(labels);

      var greenLine = new SimpleLineSymbol("solid", new Color("#00ff45"), 1);
      var countyUrl = "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/3";
      var counties = new FeatureLayer(countyUrl, {
        id:"counties",
        outFields: ["NAME"]
      });   
      var countyRenderer = new SimpleRenderer(greenLine);
      counties.setRenderer(countyRenderer);
      map.addLayer(counties);


  var countyTextColor = new Color("#000000");
  var countySymbolSm = new TextSymbol();
  countySymbolSm.font.setSize("6pt");
  countySymbolSm.setColor(countyTextColor);
  countySymbolSm.font.setFamily("arial");
  var countySmRenderer = new SimpleRenderer(countySymbolSm);



  var countySymbolMed = new TextSymbol();
  countySymbolMed.font.setSize("11pt");
  countySymbolMed.font.setFamily("arial");
  countySymbolMed.setColor(countyTextColor);
  var countyMedRenderer = new SimpleRenderer(countySymbolMed);


  var countySymbolLg = new TextSymbol();
  countySymbolLg.font.setSize("16pt");
  countySymbolLg.font.setFamily("arial");
  countySymbolLg.setColor(countyTextColor);
  var countyLgRenderer = new SimpleRenderer(countySymbolLg);

  var countyScaleDependent = new ScaleDependentRenderer({
    rendererInfos: [{
        renderer: countySmRenderer,
        minZoom: 7,
        maxZoom: 7
      },
      {
      renderer: countyMedRenderer,
        minZoom: 8,
        maxZoom: 10
      },
      {
        renderer: countyLgRenderer,
        minZoom: 11,
        maxZoom: 15
      }]
  });
   
  var coLabels = new LabelLayer({id:"coLabels", minScale:5000000});
  coLabels.addFeatureLayer(counties,countyScaleDependent,"{NAME}")
  map.addLayer(coLabels);
  on (map,'extent-change', function (evt){
  dom.byId('mapInfo').innerHTML= "lods: " + map.getLevel()+ ", scale:" +  map.getScale();
  }); 
});
    </script>
  </head>
  <body>
    <div id="mapInfo"></div>
    <div id="map"></div>
  </body>
</html>

View solution in original post

TracySchloss · ‎09-29-2015

I'm surprised there was no one who has played with this, but I couldn't find very many examples at all with scaleDependentRenderers, especially for labelLayer. It took some fiddling, but I came up with something that was satisfactory for my purposes. Hopefully this will benefit someone else.

<!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></title>
    <link rel="stylesheet" href="https://community.esri.com//js.arcgis.com/3.14/esri/css/esri.css">
    <style type="text/css">
      html, body, #map {
        height: 100%; width: 100%; margin: 0; padding: 0;
      }
    </style>

    <script type="text/javascript" src="//js.arcgis.com/3.14/"></script>
    <script type="text/javascript" >
      var map;
   
      require([
      "dojo/on",
      "dojo/dom",
        "esri/map",
        "esri/dijit/Scalebar",
        "esri/geometry/Extent",
        "esri/SpatialReference",
        "esri/layers/FeatureLayer",

        "esri/symbols/SimpleLineSymbol",
        "esri/symbols/SimpleFillSymbol", 
        "esri/symbols/TextSymbol",
        "esri/renderers/SimpleRenderer",
        "esri/renderers/ScaleDependentRenderer",
        "esri/layers/LabelLayer",

        "esri/Color",
        "dojo/domReady!"
      ], function(
        on,dom,Map, Scalebar,Extent,SpatialReference, FeatureLayer,
        SimpleLineSymbol, SimpleFillSymbol, TextSymbol, SimpleRenderer,ScaleDependentRenderer,
        LabelLayer,
        Color
      ) {

        map = new Map("map", {
      center: [-92.593, 38.5],
        zoom: 7,
        basemap:'gray'
        });
        
        var labelField = "STATE_NAME";

        // create a renderer for the states layer to override default symbology
        var statesColor = new Color("#666");
        var statesLine = new SimpleLineSymbol("solid", statesColor, 1.5);
        var statesSymbol = new SimpleFillSymbol("solid", statesLine, null);
        var statesRenderer = new SimpleRenderer(statesSymbol);
        // create a feature layer to show country boundaries
        var statesUrl = "http://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3";
        var states = new FeatureLayer(statesUrl, {
          id: "states",
          outFields: [labelField]
        });
        states.setRenderer(statesRenderer);
        map.addLayer(states);
   
        // create a text symbol to define the style of labels
        var statesLabel = new TextSymbol().setColor(statesColor);
        statesLabel.font.setSize("14pt");
        statesLabel.font.setFamily("arial");
        var statesLabelRenderer = new SimpleRenderer(statesLabel);
        var labels = new LabelLayer({
          id: "labels"
        });
        // tell the label layer to label the states feature layer
        // using the field named "STATE_NAME"
        labels.addFeatureLayer(states, statesLabelRenderer, "{" + labelField + "}");
        // add the label layer to the map
        map.addLayer(labels);

      var greenLine = new SimpleLineSymbol("solid", new Color("#00ff45"), 1);
      var countyUrl = "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/3";
      var counties = new FeatureLayer(countyUrl, {
        id:"counties",
        outFields: ["NAME"]
      });   
      var countyRenderer = new SimpleRenderer(greenLine);
      counties.setRenderer(countyRenderer);
      map.addLayer(counties);


  var countyTextColor = new Color("#000000");
  var countySymbolSm = new TextSymbol();
  countySymbolSm.font.setSize("6pt");
  countySymbolSm.setColor(countyTextColor);
  countySymbolSm.font.setFamily("arial");
  var countySmRenderer = new SimpleRenderer(countySymbolSm);



  var countySymbolMed = new TextSymbol();
  countySymbolMed.font.setSize("11pt");
  countySymbolMed.font.setFamily("arial");
  countySymbolMed.setColor(countyTextColor);
  var countyMedRenderer = new SimpleRenderer(countySymbolMed);


  var countySymbolLg = new TextSymbol();
  countySymbolLg.font.setSize("16pt");
  countySymbolLg.font.setFamily("arial");
  countySymbolLg.setColor(countyTextColor);
  var countyLgRenderer = new SimpleRenderer(countySymbolLg);

  var countyScaleDependent = new ScaleDependentRenderer({
    rendererInfos: [{
        renderer: countySmRenderer,
        minZoom: 7,
        maxZoom: 7
      },
      {
      renderer: countyMedRenderer,
        minZoom: 8,
        maxZoom: 10
      },
      {
        renderer: countyLgRenderer,
        minZoom: 11,
        maxZoom: 15
      }]
  });
   
  var coLabels = new LabelLayer({id:"coLabels", minScale:5000000});
  coLabels.addFeatureLayer(counties,countyScaleDependent,"{NAME}")
  map.addLayer(coLabels);
  on (map,'extent-change', function (evt){
  dom.byId('mapInfo').innerHTML= "lods: " + map.getLevel()+ ", scale:" +  map.getScale();
  }); 
});
    </script>
  </head>
  <body>
    <div id="mapInfo"></div>
    <div id="map"></div>
  </body>
</html>

JssrRR · ‎09-29-2015

Tracy,

I have worked with ScaleDependentRenderer, and this tutorial helped me and they have similar example, like you have come up with:

Labeling features client-side | Guide | ArcGIS API for JavaScript

TracySchloss · ‎09-29-2015

Yes, that's the one I used. I thought the use of scales in the renderer was confusing, since I think in terms of levels, so I switched it.