mapsapi-polylabeler

Yandex.Maps API Polylabeler Plugin

This module allows to set labels inside polygons on the map choosing the suitable position automatically. It is created for Yandex.Maps JS API v2.1 and based on Polylabel module

Demo1 Demo2

example img

Loading

  1. Load Yandex.Maps JS API 2.1, Polylabeler Plugin and (Area calculation plugin) (It is used by the present module) by adding the following code into the head section of your page.
<script src="https://api-maps.yandex.ru/2.1/?lang=ru_RU" type="text/javascript"></script>
<!-- Change my.cdn.tld to your CDN host name -->
<script src="https://yastatic.net/s3/mapsapi-jslibs/area/0.0.1/util.calculateArea.min.js" type="text/javascript"></script>
<script src="https://yastatic.net/s3/mapsapi-jslibs/polylabeler/1.0.1/polylabel.min.js" type="text/javascript"></script>

Simple example

Example shows, how to create label for one polygon.

ymaps.ready(['polylabel.create']).then(function () {
    const map = new ymaps.Map('map', {
        center: [65, 81],
        zoom: 5
    });
    const objectManager = new ymaps.ObjectManager();

    objectManager.add({
	type: 'Feature',
        id: 1,
        geometry: {
            type: 'Polygon',
            coordinates: [[
    	        [66 , 74],
                [68, 92],
                [59, 88],
                [62, 80],
                [66, 74]
            ]]
	},
        properties: {
  	    name: 'nameOfMyPolygon'
        },
        options: {
            labelDefaults: 'light',
            labelLayout: ''
        }
    });
    map.geoObjects.add(objectManager);
    const polylabel = new ymaps.polylabel.create(map, objectManager);
});

Launch

It is possible to work with two API entities:

Get access to the module functions by using ymaps.modules.require method:

ymaps.modules.require(['polylabel.create']).then(function (Polylabel) {
    /**
    * @param {Map} map - map instance
    * @param {GeoObjectCollection | ObjectManager} component -
    * instance of a collection or an object manager that contains polygons to be labeled
    */
    const polyLabeler = new Polylabel(map, component);
});

Documentation

The module works according to the following principle: Two labels are created for the polygon: a small (dot) and a main (label). If the main label can’t fit into the polygon, the module tries to place a small one; If both does not fit, nothing is displayed.

Methods

| Name | Returns | Description | |——|———|————-| | getLabelState(polygon) | DataManager | label state |

getLabelState

| Parameter | Type | Default value | Description | |———–|——|—————|————-| | polygon | GeoObject | - | Object, describing a polygon. Use GeoObject for the GeoObjectCollection | | | JSON | - | Use JSON for the ObjectManager |

const polyLabeler = new Polylabel(map, objectManager);
let state = polyLabeler.getLabelState(polygon);

State

write/read

| Name | Type | Default value | Value | Description | |——|——|—————|——-|————-| | visible | string|undefined | undefined | dot | Show small label | | | | | label | Show main label | | | | | none | Hide all labels | | | | | undefined | Automatic calculation |

With map zoom change the state resets to default.

In ObjectManager version of polylabeler state resets to default on any change within labels in vieport, i.e. on any zoom and almost on any drag. It’s better to set labelForceVisible option to hide labels instead of updating state’s visible.

const polyLabeler = new Polylabel(map, objectManager);
let state = polyLabeler.getLabelState(polygon);
state.set('visible', 'dot');

only read

| Name | Type | Description | |——|——|————-| | center | Array[2] | Current center of label | | currentVisibility | string | Label current visibility | | currentConfiguredVisibility | string | Label visiblity, which configured by module |

const polyLabeler = new Polylabel(map, objectManager);
let state = polyLabeler.getLabelState(polygon);
state.get('center');

Events

Labels events can be accessed through polygons. List of events can be found in GeoObject. For events handling add listener for the desired event with the prefix “label” to EventManager of GeoObjectCollection or ObjectManager.

// In this example, we listen to pointing the cursor at the label and
// moving the cursor off the label
geoObjectCollection.events.add(['labelmouseenter', 'labelmouseleave'], event => {
    // Get the polygon on which the event occured
    var polygon = event.get('target');
    // Get label state
    var state = polyLabeler.getLabelState(polygon);
    // Change the visibility of the label depending on the type of event
    state.set('visible', event.get('type') === 'labelmouseleave' ? undefined : 'label');
});

Polygon options

The label is controlled via the polygon options

* Mandatory option

Name Type Default value
labelLayout * string -
labelDotLayout string default dot layout
labelDotVisible boolean true
labelDefaults string -
labelCursor string ‘grab’
labelDotCursor string ‘grab’
labelClassName ZoomRange < string > || string -
labelForceVisible ZoomRange < string > || string -
labelTextColor ZoomRange < string > || string -
labelTextSize ZoomRange < number > || number -
labelCenterCoords ZoomRange < Array[2]< number » || Array[2]< number > -
labelOffset ZoomRange < Array[2]< number » || Array[2]< number > [0, 0]
labelPermissibleInaccuracyOfVisibility ZoomRange < number > || number 0

Type ZoomRange< T > object allows to set zoom level or zoom range to specify values for the certain scales. T - type of value.</br>

// In this example we specify 'someOptions' value for different zoom levels
// for the 1-st zoom it will be set to 12,
// from 2-nd to 5-th the value is 14, from 6-th to 22-nd it is 16 and on the 23-rd it is 18
someOptions: {
    1: 12,
    '2_5': 14,
    '6_22': 16,
    23: 18
}
// or you can specify same value for all zoom levels
someOptions: 12
// if you skip some zoom levels, they will have a value calculated automatically or they will be simply ignored
someOptions: {
    1: 12,
    '2_3': 13
}

labelLayout

Template that describes the layout of a main label. Based on Template

polygon.options.set({
	labelLayout: '<div class="foo">bar</div>'
});

labelDotLayout

Template that describes the layout of a small label (dot).

Default behavior: If you do not specify this option, the default dot will be drawn.

polygon.options.set({
        labelDotLayout: `<div style="background: red;
            width: 10px; height: 10px; border-radius: 5px;"></div>`
});

labelDotVisible

Responsible for small labels displaying.

Default behavior: Small labels are displayed.

labelDefaults

Responsible for the labels default layout

Values:

labelCursor

Cursor type to be displayed when hovering over the main label. Possible Values

labelDotCursor

Cursor type to be displayed when hovering over the small label. Possible Values

labelClassName

CSS-class name to be applied to the label. Important: if you use labelDefaults option, labelClassName doesn’t work.

// Apply "foo-class" to the label on the first zoom level,
// for others apply 'bar-class"

polygon.options.set({
        labelClassName: {
            1: 'foo-class',
            '2_23': 'bar-class'
        }
});

labelForceVisible

Label type to be displayed.

// On the first two zoom levels, the main label will be always shown.
// On the others - small label will be always shown.

polygon.options.set({
        labelForceVisible: {
            '0_1': 'label',
            '2_23': 'dot'
        }
});

Default behavior: Automatic calculation.

labelTextColor

Label font color.

//Set '#FCEA00' as labels font color for all zoom levels
polygon.options.set({
        labelTextColor: '#FCEA00'
});

labelTextSize

Label font size.

// On the first five zoom levels, labels font size is '22'.
// On the others - '11'.
polygon.options.set({
        labelTextSize: {
            '0_4': 22,
            '5_23': 11
        }
});

labelCenterCoords

Geographic coordinates where the label will be displayed.

// On the first zoom level coords - [37.0192, 61.01210]
// On the next two - [38.123, 62.9182]
// On the others - Automatic calculation
polygon.options.set({
        labelCenterCoords: {
            0: [37.0192, 61.01210],
            '2_3': [38.123, 62.9182]
        }
});

Default behavior: Automatic calculation.

labelOffset

Offset in pixels from the current position of the label.

//Set labels offset to the left as 10px and down as 20px
polygon.options.set({
        labelOffset: [-10, 20]
});

Default behavior: labelOffset: [0, 0]

labelPermissibleInaccuracyOfVisibility

The value in pixels describing max area outside of the polygon that could be occupied by the label.

// Allow labels to step out of the polygon for 2px at all zoom levels
polygon.options.set({
        labelPermissibleInaccuracyOfVisibility: 2
});

Default behavior: labelPermissibleInaccuracyOfVisibility: 0

Used libraries

https://github.com/mapbox/polylabel

Third party components

The views and conclusions contained in the software and documentation are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of OpenLayers Contributors.

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