# BaseLayerPicker

#### new Cesium.BaseLayerPicker(container, options)
Widgets/BaseLayerPicker/BaseLayerPicker.js 91

BaseLayerPicker with its drop-panel open.
The BaseLayerPicker is a single button widget that displays a panel of available imagery and terrain providers. When imagery is selected, the corresponding imagery layer is created and inserted as the base layer of the imagery collection; removing the existing base. When terrain is selected, it replaces the current terrain provider. Each item in the available providers list contains a name, a representative icon, and a tooltip to display more information when hovered. The list is initially empty, and must be configured before use, as illustrated in the below example.

Name | Type | Description
--- | --- | ---
`container` | Element | String | The parent HTML container node or ID for this widget.
`options` | Object | Object with the following properties:
Name | Type | Default | Description
--- | --- | --- | ---
`globe` | Globe |  | The Globe to use.
`imageryProviderViewModels` | Array.<ProviderViewModel> | `[]` | optional The array of ProviderViewModel instances to use for imagery.
`selectedImageryProviderViewModel` | ProviderViewModel |  | optional The view model for the current base imagery layer, if not supplied the first available imagery layer is used.
`terrainProviderViewModels` | Array.<ProviderViewModel> | `[]` | optional The array of ProviderViewModel instances to use for terrain.
`selectedTerrainProviderViewModel` | ProviderViewModel |  | optional The view model for the current base terrain layer, if not supplied the first available terrain layer is used.

##### Throws:

- DeveloperError : Element with id "container" does not exist in the document.

##### Example:

    // In HTML head, include a link to the BaseLayerPicker.css stylesheet,
    // and in the body, include: <div id="baseLayerPickerContainer"
    //   style="position:absolute;top:24px;right:24px;width:38px;height:38px;"></div>

    //Create the list of available providers we would like the user to select from.
    //This example uses 3, OpenStreetMap, The Black Marble, and a single, non-streaming world image.
    var imageryViewModels = [];
    imageryViewModels.push(new Cesium.ProviderViewModel({
         name : 'Open\u00adStreet\u00adMap',
         iconUrl : Cesium.buildModuleUrl('Widgets/Images/ImageryProviders/openStreetMap.png'),
         tooltip : 'OpenStreetMap (OSM) is a collaborative project to create a free editable \
    map of the world.\nhttp://www.openstreetmap.org',
         creationFunction : function() {
             return new Cesium.OpenStreetMapImageryProvider({
                 url : 'https://a.tile.openstreetmap.org/'
             });
         }
     }));

     imageryViewModels.push(new Cesium.ProviderViewModel({
         name : 'Earth at Night',
         iconUrl : Cesium.buildModuleUrl('Widgets/Images/ImageryProviders/blackMarble.png'),
         tooltip : 'The lights of cities and villages trace the outlines of civilization \
    in this global view of the Earth at night as seen by NASA/NOAA\'s Suomi NPP satellite.',
         creationFunction : function() {
             return new Cesium.IonImageryProvider({ assetId: 3812 });
         }
     }));

     imageryViewModels.push(new Cesium.ProviderViewModel({
         name : 'Natural Earth\u00a0II',
         iconUrl : Cesium.buildModuleUrl('Widgets/Images/ImageryProviders/naturalEarthII.png'),
         tooltip : 'Natural Earth II, darkened for contrast.\nhttp://www.naturalearthdata.com/',
         creationFunction : function() {
             return new Cesium.TileMapServiceImageryProvider({
                 url : Cesium.buildModuleUrl('Assets/Textures/NaturalEarthII')
             });
         }
     }));

    //Create a CesiumWidget without imagery, if you haven't already done so.
    var cesiumWidget = new Cesium.CesiumWidget('cesiumContainer', { imageryProvider: false });

    //Finally, create the baseLayerPicker widget using our view models.
    var layers = cesiumWidget.imageryLayers;
    var baseLayerPicker = new Cesium.BaseLayerPicker('baseLayerPickerContainer', {
        globe : cesiumWidget.scene.globe,
        imageryProviderViewModels : imageryViewModels
    });

##### See:

- TerrainProvider
- ImageryProvider
- ImageryLayerCollection

### Members

#### container : Element
Widgets/BaseLayerPicker/BaseLayerPicker.js 263

Gets the parent container.

#### viewModel : BaseLayerPickerViewModel
Widgets/BaseLayerPicker/BaseLayerPicker.js 275

Gets the view model.

### Methods

#### destroy()
Widgets/BaseLayerPicker/BaseLayerPicker.js 293

Destroys the widget. Should be called if permanently removing the widget from layout.

#### isDestroyed() → Boolean
Widgets/BaseLayerPicker/BaseLayerPicker.js 285

##### Returns:

true if the object has been destroyed, false otherwise.