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Class: LabelClass
[ AMD Module Require | Legacy Module Require ]
require(["esri/layers/LabelClass"], function(LabelClass) { /* code goes here */ });
Description
(Added at v3.6)
Use label classes to restrict labels to certain features or to specify different label fields, symbols, scale ranges, label priorities, and sets of label placement options for different groups of labels.Samples
Search for samples that use this class.Constructors
| Name | Summary |
|---|---|
| new LabelClass(json?) | Creates a label class, used for formatting parameters, symbols, date, etc. |
Properties
| Name | Type | Summary |
|---|---|---|
| fieldInfos | Object[] | An array of objects representing field information to label. |
| labelExpression | String | Adjusts the formatting of labels. |
| labelExpressionInfo | Object | Use this property when working with FeatureLayer layer types. |
| labelPlacement | String | The position of the label. |
| maxScale | Number | The maximum scale to show labels. |
| minScale | Number | The minimum scale to show labels. |
| sizeInfo | Object | If this is defined, the symbol size changes proportionally. |
| symbol | TextSymbol | Sets the Rendering symbol for the label. |
| useCodedValues | Boolean | When true, show the fields in the labelExpression that have domains using the domain's name. |
| where | String | A where clause determining which features are labeled. |
Constructor Details
Creates a label class, used for formatting parameters, symbols, date, etc.
Parameters:
< |
Optional | Various options to configure this LabelClass. Any property can be passed into this object. |
Sample:
//make sure the Map's showLabels option is set to true
var map = new Map("map", {
basemap: "streets",
center:[-80, 30],
zoom: 5,
showLabels : true
});
//create featurelayer
var flayer = new FeatureLayer(url, {
outFields: ["*"] //make sure field to label is specified here in outFields
});
//create a text symbol and renderer to define the style of labels
var labelSymbol = new TextSymbol();
var json = {
"labelExpressionInfo": {"value": "{LocalTime}"},
"useCodedValues": false,
"labelPlacement":"above-right",
"fieldInfos": [{fieldName: "LocalTime",format: { "dateFormat": "shortDate"}}]
};
//create instance of LabelClass
var lc = new LabelClass(json);
lc.symbol = labelSymbol; // symbol also can be set in LabelClass' json
flayer.setLabelingInfo([ lc ]);
Property Details
<Object[]
Object[]An array of objects representing field information to label. This is used for formatting Date/Time and Number. It is not necessary if working with string types. See the fieldInfos specifications table below for additional information. (Added at v3.14)
Object Specifications:
<
fieldInfos>< |
Optional | The name of the field to label. This should only be used when working with Date/Time and Number field types. |
< |
Optional | This object can be used with numerical or date fields to provide more detail about how values should be displayed in labels. NOTE: Only applies to date or number fields, (for example float, double, integer). The format object contains the following properties:
"fieldInfos": [
{ fieldName: "created_date",
format: { dateFormat: "shortDate"}
},
{
fieldName: "last_edited_date",
format: { dateFormat: "longDate"}
},
{
fieldName: "eventtype",
format: { places: 6, digitSeparator: true }
}
]
|
Sample:
"fieldInfos": [{
fieldName: "LocalTime",
format:{"dateFormat": "shortDate"}
}
]
<String
StringAdjusts the formatting of labels. See the Labeling Objects section of the ArcGIS REST API documentation for available options. NOTE: Currently
labelExpression is not supported with FeatureLayer types, please use labelExpressionInfo instead. This supports using a combination of attribute fields and simple text. If working with ArcGISDynamicMapServiceLayer layers, please continue to use labelExpression.Sample:
"Name: {CITY_NAME} Area: {CITY_AREA}"
<Object
ObjectUse this property when working with FeatureLayer layer types. See the object specification table for labelExpressionInfo below for more details. If working with ArcGISDynamicMapServiceLayer layers, use
labelExpression since labelExpressionInfo is not supported. (Added at v3.12)Object Specifications:
<
labelExpressionInfo>< |
Required | An Arcade expression that evaluates to a string used to label features in the layer. The most simple expressions return field values. For example, to label a layer of cities with their names, simply reference the field value with the global variable: "$feature.CITY_NAME". Expressions can be more sophisticated and use logical functions. This may be useful if you want to use classed labels. For example, "IIF($feature.POPULATION > 10000, $feature.NAME + ' city', $feature.NAME + ' town')". |
< |
Optional | Deprecated at v3.19. Use the expression property instead. The text used to label the feature. Field values may be referenced using the following syntax: "{FIELD_NAME}". For example, to label points representing city's with their name and population in parentheses, you would use the following string: labelExpressionInfo.value = "{CITY_NAME} ({POP_2012})" |
Sample:
//This property should be used instead as it provides more options when labeling text, (only supported with feature layers)
labelExpressionInfo: {
expression: "City of $feature.CITY_NAME has population $feature.POPULATION"
}
<String
StringThe position of the label. Available values for various feature types:
- Point: "above-center", "above-left", "above-right", "below-center", "below-left", "below-right", "center-center", "center-left", "center-right"
- Polyline/Line: "above-after", "above-along", "above-before", "above-start", "above-end", "below-after", "below-along", "below-before", "below-start", "below-end", "center-after", "center-along", "center-before", "center-start", "center-end"
- Polygon: "always-horizontal"
<Number
NumberThe maximum scale to show labels. Note: the number of
maxScale should always be less than the number of minScale.<Number
NumberThe minimum scale to show labels. Note: the number of
minScale should always be greater than the number of maxScale.<Object
ObjectIf this is defined, the symbol size changes proportionally. See the object specifications table below for a list of its available properties. (Added at v3.11)
Object Specifications:
<
sizeInfo>< |
Required | Required name of the feature attribute field that contains the data value. |
< |
Required | The maximum data value. |
< |
Required | Maximum symbol size (in pixels). |
< |
Required | The minimum data value. |
< |
Required | The symbol size (in pixels) to use for a feature for a minimum data value. |
Sample:
var sizeInfo = {
"field": "POP_RANK",
"minSize": 10,
"maxSize": 20,
"minDataValue": 1,
"maxDataValue": 7
};
<TextSymbol
TextSymbolSets the Rendering symbol for the label.
Sample:
require([
"esri/layers/LabelClass", "esri/symbols/TextSymbol", "esri/symbols/Font", "esri/Color", ...
], function(LabelClass, TextSymbol, Font, Color){
var labelClass = new LabelClass();
labelClass.symbol = new TextSymbol({
font: new Font("12", Font.STYLE_NORMAL, Font.VARIANT_NORMAL, Font.WEIGHT_BOLD, "Helvetica"),
color: new Color("#666633")
});
});<Boolean
BooleanWhen true, show the fields in the
labelExpression that have domains using the domain's name.Known values:
true | false<String
StringA where clause determining which features are labeled. When specified, only features that match this clause will be labeled. Only very basic SQL is supported.
Sample:
labelClass.where = "STATE_NAME = 'California'";