Hide Table of Contents
Analysis
Data Reviewer
Dynamic Layers
Editing
Feature Layers
Feature Table
Graphics
Map
Mobile
Online and Portal
Popups and Info Windows
Query and Select
Renderers, Symbols, Visualization
Search
Geometry Service - Points for labeling
Explore in the sandbox
Share
View live sample
Download as a zip file
Description
As an alternative to the label layer, you can create a label for one or more individual features by placing a text symbol at a given point. To do this, use the geometry service to generate a point for placing a label inside a polygon.
To try this sample, draw a polygon on the map. When you submit the polygon, it's simplified so it won't throw errors if it overlaps itself. The GeometryService.labelPoints() method determines a point inside the polygon. The parameters are an array of polygon graphics to be labeled and a callback function specifying what to do with the label points. In most cases, you'll be associating each point with a TextSymbol, like this:
labelPoints[i].setSymbol(textSymbol);
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>Geometry Service: Label Points</title>
<link rel="stylesheet" href="https://js.arcgis.com/3.26/dijit/themes/nihilo/nihilo.css">
<link rel="stylesheet" href="https://js.arcgis.com/3.26/esri/css/esri.css">
<style>
html, body, #mapDiv {
height: 100%;
margin: 0;
padding: 0;
width: 100%;
}
#info {
bottom: 20px;
color: #444;
height: auto;
font-family: arial;
left: 20px;
margin: 5px;
padding: 10px;
position: absolute;
width: 200px;
z-index: 40;
}
</style>
<script src="https://js.arcgis.com/3.26/"></script>
<script>
require(["dojo/dom",
"dojo/dom-attr",
"dojo/_base/array",
"esri/Color",
"dojo/number",
"dojo/parser",
"dijit/registry",
"esri/config",
"esri/map",
"esri/graphic",
"esri/tasks/GeometryService",
"esri/tasks/BufferParameters",
"esri/toolbars/draw",
"esri/symbols/SimpleMarkerSymbol",
"esri/symbols/SimpleLineSymbol",
"esri/symbols/SimpleFillSymbol",
"esri/symbols/Font",
"esri/symbols/TextSymbol",
"dijit/layout/BorderContainer",
"dijit/layout/ContentPane"
], function(dom, domAttr, array, Color, number, parser, registry, esriConfig, Map, Graphic, GeometryService, BufferParameters, Draw,
SimpleMarkerSymbol, SimpleLineSymbol, SimpleFillSymbol, Font, TextSymbol) {
var map, toolbar, geometryService;
parser.parse();
// create the map control
map = new Map("mapDiv", {
basemap: "streets",
center: [-117.215, 34.05],
zoom: 13,
showAttribution: false
});
// configure the proxy url for the application
esriConfig.defaults.io.proxyUrl = "/proxy/";
esriConfig.defaults.io.alwaysUseProxy = false;
// create a toolbar for the map
toolbar = new Draw(map);
toolbar.on("draw-end", addToMap);
// activate a drawing tool when a button is clicked
registry.byId("polygon").on("click", function() {
toolbar.activate(Draw.POLYGON);
map.hideZoomSlider();
});
registry.byId("freehand").on("click", function() {
toolbar.activate(Draw.FREEHAND_POLYGON);
map.hideZoomSlider();
});
registry.byId("clear").on("click", function() {
map.graphics.clear();
});
geometryService = new GeometryService("https://utility.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer");
function addToMap(evtObj) {
map.graphics.clear();
var geometry = evtObj.geometry;
// add the drawn graphic to the map
var symbol = new SimpleFillSymbol(
SimpleFillSymbol.STYLE_SOLID,
new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID, new Color([0, 0, 0]), 2),
new Color([0, 0, 255, 0.5]));
var graphic = new Graphic(geometry, symbol);
map.graphics.add(graphic);
// simplify polygon so it can be used in the get label points request
geometryService.simplify([geometry], getLabelPoints);
}
function getLabelPoints(geometries) {
if (geometries[0].rings.length > 0) {
geometryService.labelPoints(geometries, function(labelPoints) { // callback
toolbar.deactivate();
map.showZoomSlider();
var font = new Font("20px", Font.STYLE_NORMAL, Font.VARIANT_NORMAL, Font.WEIGHT_BOLDER);
array.forEach(labelPoints, function(labelPoint) {
// create a text symbol
var textSymbol = new TextSymbol(
"X: " + number.format(labelPoint.x) + ", Y: " + number.format(labelPoint.y),
font, new Color([0, 0, 0]));
var labelPointGraphic = new Graphic(labelPoint, textSymbol);
// add the label point graphic to the map
map.graphics.add(labelPointGraphic);
});
});
} else {
alert("Invalid Polygon - must have at least 3 points");
}
}
});
</script>
</head>
<body class="nihilo">
<div id="mapDiv"></div>
<div id="info" class="esriSimpleSlider">
<button id="polygon" data-dojo-type="dijit.form.Button">Polygon</button>
<button id="freehand" data-dojo-type="dijit.form.Button">Freehand Polygon</button>
<button id="clear" data-dojo-type="dijit.form.Button">Clear Graphics</button>
</div>
</body>
</html>