Maps API for JavaScript Developer's Guide

H.map.layer.Layer

Class Summary

The Layer class represents an object that is evaluated by the renderer in the order in which it is added to the collection of map layers. It provides the basic infrastructure for dispatching update events to the renderer when new data is available.

[ For full details, see the Class Details ]

Method Summary

Table 1. Methods
Methods
`getProvider () : {H.map.provider.Provider}` This method returns the provider which feeds this layer with data.
`isValid (zoomLevel) : {boolean}` This method checks if a zoom level can be served by the given layer.
`setMin (min) : {H.map.layer.Layer}` This method sets the minimum zoom level at which the given layer provides content.
`setMax (max) : {H.map.layer.Layer}` This method sets the maximum zoom level at which the given layer provides content.
`getCopyrights (boundingBox, level) : {?Array<H.map.ICopyright>}` This method retrieves the copyright of the current data provider.
`addEventListener (type, handler, opt_capture, opt_scope)` This method adds a listener for a specific event.
`removeEventListener (type, handler, opt_capture, opt_scope)` This method removes a previously added listener from the `EventTarget` instance.
`dispatchEvent (evt)` This method dispatches an event on the `EventTarget` object.
`dispose ()` This method removes listeners from the given object. Classes that extend `EventTarget` may need to override this method in order to remove references to DOM Elements and additional listeners.
`addOnDisposeCallback (callback, opt_scope)` This method adds a callback which is triggered when the `EventTarget` object is being disposed.

Events Summary

Table 2. Events
Events
`update : {H.util.Event}` Event fired when the data associated with the given layer is updated.

Class Description

A layer is defined by a minimum and maximum zoom level for which it can provide data to the renderer and a projection it uses to transform geographic coordinates into 2D projected world coordinates.

Constructor Details

H.map.layer.Layer(opt_options)

Parameters:
opt_options:: {H.map.layer.Layer.Options=} [optional]
: An optional configuration object

Method Details

getProvider () : {H.map.provider.Provider}

This method returns the provider which feeds this layer with data.

Returns:
: {H.map.provider.Provider}
: this layer's provider

isValid (zoomLevel) : {boolean}

This method checks if a zoom level can be served by the given layer.

Parameters:
zoomLevel:: {number}
: The zoom level to check

Returns:
: {boolean}
: true if the given layer can provide data for the zoom level, otherwise false

setMin (min) : {H.map.layer.Layer}

This method sets the minimum zoom level at which the given layer provides content.

Parameters:
min:: {number}
: The new minimum zoom level for the given layer

Returns:
: {H.map.layer.Layer}
: An object representing the given layer

Throws:
: {H.lang.InvalidArgumentError}
: if the `min` parameter is not a number or if it is larger that the current maximum zoom level

setMax (max) : {H.map.layer.Layer}

This method sets the maximum zoom level at which the given layer provides content.

Parameters:
max:: {number}
: The new maximum zoom level for the given layer

Returns:
: {H.map.layer.Layer}
: An object representing the given layer

Throws:
: {H.lang.InvalidArgumentError}
: if the `max` parameter is not a number or if it is smaller that the current minimum zoom level

getCopyrights (boundingBox, level) : {?Array<H.map.ICopyright>}

This method retrieves the copyright of the current data provider.

Note: This function must be overridden by any class derived from Layer. The default implementation returns null.

Parameters:
boundingBox:: {H.geo.Rect}
: The bounding box for which to retrieve the copyright information
level:: {number}
: The zoom level for which to retrieve the copyright information

Returns:
: {?Array<H.map.ICopyright>}
: A list of copyright information objects for the provided area and zoom level

addEventListener (type, handler, opt_capture, opt_scope)

This method adds a listener for a specific event.

Note that to prevent potential memory leaks, you must either call removeEventListener or dispose on the given object when you no longer need it.

Parameters:
type:: {string}
: The name of the event
handler:: {!Function}
: An event handler function
opt_capture:: {boolean=} [optional]
: true indicates that the method should listen in the capture phase (bubble otherwise)
opt_scope:: {Object=} [optional]
: An object defining the scope for the handler function

removeEventListener (type, handler, opt_capture, opt_scope)

This method removes a previously added listener from the EventTarget instance.

Parameters:
type:: {string}
: The name of the event
handler:: {!Function}
: A previously added event handler
opt_capture:: {boolean=} [optional]
: true indicates that the method should listen in the capture phase (bubble otherwise)
opt_scope:: {Object=} [optional]
: An oject defining the scope for the handler function

dispatchEvent (evt)

This method dispatches an event on the EventTarget object.

Parameters:
evt:: {(H.util.Event | string)}
: An object representing the event or a string with the event name

dispose ()

This method removes listeners from the given object. Classes that extend EventTarget may need to override this method in order to remove references to DOM Elements and additional listeners.

addOnDisposeCallback (callback, opt_scope)

This method adds a callback which is triggered when the EventTarget object is being disposed.

Parameters:
callback:: {!Function}
: The callback function.
opt_scope:: {Object=} [optional]
: An optional scope for the callback function

Event Details

update: {H.util.Event}

Event fired when the data associated with the given layer is updated.