ImageryLayerCollection

成员(属性)

An event that is raised when a layer is added to the collection. Event handlers are passed the layer that was added and the index at which it was added.
默认值: Event()
An event that is raised when a layer changes position in the collection. Event handlers are passed the layer that was moved, its new index after the move, and its old index prior to the move.
默认值: Event()
An event that is raised when a layer is removed from the collection. Event handlers are passed the layer that was removed and the index from which it was removed.
默认值: Event()
An event that is raised when a layer is shown or hidden by setting the ImageryLayer#show property. Event handlers are passed a reference to this layer, the index of the layer in the collection, and a flag that is true if the layer is now shown or false if it is now hidden.
默认值: Event()
Gets the number of layers in this collection.

方法

Adds a layer to the collection.
参数名称 类型 描述信息
layer ImageryLayer the layer to add.
index number 可选 the index to add the layer at. If omitted, the layer will be added on top of all existing layers.
Throws:
  • DeveloperError : index, if supplied, must be greater than or equal to zero and less than or equal to the number of the layers.
使用示例s:
const imageryLayer = Cesium.ImageryLayer.fromWorldImagery();
scene.imageryLayers.add(imageryLayer);
const imageryLayer = Cesium.ImageryLayer.fromProviderAsync(Cesium.IonImageryProvider.fromAssetId(3812));
scene.imageryLayers.add(imageryLayer);

addImageryProvider(imageryProvider, index)ImageryLayer

Creates a new layer using the given ImageryProvider and adds it to the collection.
参数名称 类型 描述信息
imageryProvider ImageryProvider the imagery provider to create a new layer for.
index number 可选 the index to add the layer at. If omitted, the layer will added on top of all existing layers.
返回值:
The newly created layer.
使用示例:
try {
   const provider = await Cesium.IonImageryProvider.fromAssetId(3812);
   scene.imageryLayers.addImageryProvider(provider);
} catch (error) {
  console.log(`There was an error creating the imagery layer. ${error}`)
}
Checks to see if the collection contains a given layer.
参数名称 类型 描述信息
layer ImageryLayer the layer to check for.
返回值:
true if the collection contains the layer, false otherwise.
Destroys the WebGL resources held by all layers in this collection. Explicitly destroying this object allows for deterministic release of WebGL resources, instead of relying on the garbage collector.

Once this object is destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception. Therefore, assign the return value (undefined) to the object as done in the example.
Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
使用示例:
layerCollection = layerCollection && layerCollection.destroy();
参考:
Gets a layer by index from the collection.
参数名称 类型 描述信息
index number the index to retrieve.
返回值:
The imagery layer at the given index.
Determines the index of a given layer in the collection.
参数名称 类型 描述信息
layer ImageryLayer The layer to find the index of.
返回值:
The index of the layer in the collection, or -1 if the layer does not exist in the collection.
Returns true if this object was destroyed; otherwise, false.

If this object was destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception.
返回值:
true if this object was destroyed; otherwise, false.
参考:
Lowers a layer down one position in the collection.
参数名称 类型 描述信息
layer ImageryLayer the layer to move.
Throws:
Lowers a layer to the bottom of the collection.
参数名称 类型 描述信息
layer ImageryLayer the layer to move.
Throws:

pickImageryLayerFeatures(ray, scene)Promise.<Array.<ImageryLayerFeatureInfo>>|undefined

Asynchronously determines the imagery layer features that are intersected by a pick ray. The intersected imagery layer features are found by invoking ImageryProvider#pickFeatures for each imagery layer tile intersected by the pick ray. To compute a pick ray from a location on the screen, use Camera.getPickRay.
参数名称 类型 描述信息
ray Ray The ray to test for intersection.
scene Scene The scene.
返回值:
A promise that resolves to an array of features intersected by the pick ray. If it can be quickly determined that no features are intersected (for example, because no active imagery providers support ImageryProvider#pickFeatures or because the pick ray does not intersect the surface), this function will return undefined.
使用示例:
const pickRay = viewer.camera.getPickRay(windowPosition);
const featuresPromise = viewer.imageryLayers.pickImageryLayerFeatures(pickRay, viewer.scene);
if (!Cesium.defined(featuresPromise)) {
    console.log('No features picked.');
} else {
    Promise.resolve(featuresPromise).then(function(features) {
        // This function is called asynchronously when the list if picked features is available.
        console.log(`Number of features: ${features.length}`);
        if (features.length > 0) {
            console.log(`First feature name: ${features[0].name}`);
        }
    });
}

pickImageryLayers(ray, scene)Array.<ImageryLayer>|undefined

Determines the imagery layers that are intersected by a pick ray. To compute a pick ray from a location on the screen, use Camera.getPickRay.
参数名称 类型 描述信息
ray Ray The ray to test for intersection.
scene Scene The scene.
返回值:
An array that includes all of the layers that are intersected by a given pick ray. Undefined if no layers are selected.
Raises a layer up one position in the collection.
参数名称 类型 描述信息
layer ImageryLayer the layer to move.
Throws:
Raises a layer to the top of the collection.
参数名称 类型 描述信息
layer ImageryLayer the layer to move.
Throws:

remove(layer, destroy)boolean

Removes a layer from this collection, if present.
参数名称 类型 默认值 描述信息
layer ImageryLayer The layer to remove.
destroy boolean true 可选 whether to destroy the layers in addition to removing them.
返回值:
true if the layer was in the collection and was removed, false if the layer was not in the collection.
Removes all layers from this collection.
参数名称 类型 默认值 描述信息
destroy boolean true 可选 whether to destroy the layers in addition to removing them.