2gis-maps/src/doc/en/manual/dg-metalayers.md

Interactive 2GIS maps API, based on Leaflet

## Meta Layers

Allows you to create additional layers of meta information and add them to the map.

{toc}

### DG.Meta.layer

Inherits from <a href="/doc/maps/en/manual/base-classes#dglayer"><code>DG.Layer</code></a>.

#### Creation

<table>
    <thead>
        <tr>
            <th>Factory</th>
            <th>Usage</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>DG.Meta.layer</b>(
                <nobr>&lt;String&gt; <i>source</i>,</nobr>
                <nobr>&lt;<a href="#options">DG.Meta.layer options</a>&gt; <i>options?</i> )</nobr>
            </code></td>
            <td><code>DG.Meta.layer(&hellip;)</code></td>
            <td>Creates additional layer with meta-information. Takes the source URL as a parameter
                with which the tiles of an additional layer are available.</td>
        </tr>
    </tbody>
</table>

#### Options

<table>
    <thead>
        <tr>
            <th>Option</th>
            <th>Type</th>
            <th>Default</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>tileSize</b></code></td>
            <td><code>Number</code></td>
            <td><code>256</code></td>
            <td>The tile size (width and height in pixels, it is assumed that the tile is square).</td>
        </tr>
        <tr>
            <td><code><b>minZoom</b></code></td>
            <td><code>Number</code></td>
            <td><code>0</code></td>
            <td>The minimum zoom level.</td>
        </tr>
        <tr>
            <td><code><b>maxZoom</b></code></td>
            <td><code>Number</code></td>
            <td><code>18</code></td>
            <td>The maximum zoom level.</td>
        </tr>
        <tr>
            <td><code><b>zoomOffset</b></code></td>
            <td><code>Number</code></td>
            <td><code>0</code></td>
            <td>Value which will shift the zoom level in the tile's address.</td>
        </tr>
        <tr>
            <td><code><b>eventBubbling</b></code></td>
            <td><code>String</code></td>
            <td><code><span class="string">'transparent'</span>||<span class="string">'layer'</span></td>
            <td>The way in which meta-layer handles events. Accepts values <b>layer</b>
                or <b>transparent</b> (default):<ul><li>transparent &mdash; meta-layer receives all of the events
                and carry them to the map</li><li>layer &mdash; meta-layer receives all of the events and stops
                them after processing</li></ul></td>
        </tr>
    </tbody>
</table>

#### Events

You can subscribe to the following events using
<a href="/doc/maps/en/manual/base-classes#dgevented">these</a> methods.

<table>
    <thead>
        <tr>
            <th>Event</th>
            <th>Data</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>mouseover</b></code></td>
            <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code>
            <td>Called when you hover the mouse over the additional layer object.</td>
        </tr>
        <tr>
            <td><code><b>mouseout</b></code></td>
            <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code>
            <td>Called when the mouse cursor leaves the bounds of an additional layer object.</td>
        </tr>
        <tr>
          <td><code><b>mousemove</b></code></td>
          <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code></td>
          <td>Called when the mouse cursor moves over an additional layer object.</td>
        </tr>
        <tr>
          <td><code><b>click</b></code></td>
          <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code></td>
          <td>Called when the mouse click in the additional layer.</td>
        </tr>
        <tr>
          <td><code><b>dblclick</b></code></td>
          <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code></td>
          <td>Called when the mouse double-click in the additional layer.</td>
        </tr>
        <tr>
          <td><code><b>mousedown</b></code></td>
          <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code></td>
          <td>Called when the mouse button is pressed while the cursor is over the additional layer.</td>
        </tr>
        <tr>
          <td><code><b>contextmenu</b></code></td>
          <td><code><a href="/doc/maps/en/manual/base-classes#metaevent">MetaEvent</a></code></td>
          <td>Called when you click the right mouse button in the additional layer.</td>
        </tr>
    </tbody>
</table>

#### Methods

<table>
    <thead>
        <tr>
            <th>Method</th>
            <th>Returns</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>getOrigin</b>()</code></td>
            <td><code>Object</code></td>
            <td>Returns origin-instance of additional layer.</td>
        </tr>
    </tbody>
</table>

### DG.Meta.origin

Works with the meta data of a layer, inherits from <a href="/doc/maps/en/manual/base-classes#dgclass"><code>DG.Class</code></a>.

#### Creation

<table>
    <thead>
        <tr>
            <th>Factory</th>
            <th>Usage</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>DG.Meta.origin</b>(
                <nobr>&lt;String&gt; <i>source</i>,</nobr>
                <nobr>&lt;DG.Meta.layer options&gt; <i>options?</i> )</nobr>
            </code></td>
            <td><code>DG.Meta.origin(&hellip;)</code></td>
            <td>Creates an instance for work with the meta layer data. Takes the source URL as a parameter
                with which the tiles of an additional layer are available.</td>
        </tr>
    </tbody>
</table>

#### Options

<table>
    <thead>
        <tr>
            <th>Option</th>
            <th>Type</th>
            <th>Default</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>subdomains</b></code></td>
            <td><code>String</code> или <code>String[]</code></td>
            <td><code>'0123'</code></td>
            <td>Tile service subdomains. Can be sent as one string (where each letter &mdash;
                is a subdomain name) or as an array of strings.</td>
        </tr>
        <tr>
            <td><code><b>dataFilter</b></code></td>
            <td><code>Function</code></td>
            <td><code>null</code></td>
            <td>Optional parameter, which takes a function to filter or convert the meta data
                received from the server.</td>
        </tr>
    </tbody>
</table>

#### Methods

<table>
    <thead>
        <tr>
            <th>Method</th>
            <th>Returns</th>
            <th>Description</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><code><b>getTileData</b>(
                <nobr>&lt;Object&gt; <i>coord</i>)</nobr>
            </code>
            <td><code>Object</code></td>
            <td>Returns the metadata of the meta layer for the specified tile.</td>
        </tr>
        <tr>
            <td><code><b>setTileData</b>(
                <nobr>&lt;String&gt;/&lt;Object&gt; <i>coord</i>,</nobr>
                <nobr>&lt;Object&gt; <i>data</i>)</nobr>
            </code>
            <td><code>this</code></td>
            <td>Assigns data for the tile with the coord key.</td>
        </tr>
        <tr>
            <td><code><b>flush</b>()</code></td>
            <td><code>this</code></td>
            <td>Clear cached data for all tiles.</td>
        </tr>
        <tr>
            <td><code><b>setURL</b>(
                <nobr>&lt;String&gt; <i>url</i>,</nobr>
                <nobr>&lt;Boolean&gt; <i>flush?</i>)</nobr>
            </code>
            <td><code>this</code></td>
            <td>Sets the url used to get the meta data. If the parameter flush=true,
                the cached data will be cleared.</td>
        </tr>
        <tr>
            <td><code><b>getTileKey</b>(
                <nobr>&lt;Object&gt; <i>coord</i>)</nobr>
            </code>
            <td><code>String</code></td>
            <td>Returns the key of the tile as a string.</td>
        </tr>
    </tbody>
</table>