Base class for all layers that can be added to a map.
Use ArcGISTiledMapServiceLayer for cached data,
ArcGISDynamicMapServiceLayer for non-cached data,
ArcIMSMapServiceLayer for ArcIMS services,
ArcGISImageServiceLayer for ArcGIS Image Services,
VETiledLayer for Bing Maps (formerly Microsoft Virtual Earth) mapping and
GraphicsLayer to display additional features on the map.
You can also extend Layer (or, preferably, DynamicMapServiceLayer or TiledMapServiceLayer) to add support for additional map types.
Note that all layers extend UIComponent and thus include basic mouse events, such as:
click,
mouseOut,
mouseOver, and
mouseDown,
as well as other events like
show and
hide,
and general properties, such as
alpha and
visible.
initialExtent:Extent [read-only]
The initial extent of the layer. Used for the map if it's the first layer in the map and map doesn't have an extent specified.
Subclasses should override this method as a best practice in case a subclassed layer is added to a map which doesn't have an extent.
The default value is new Extent(-180, -90, 180, 90, new SpatialReference(4326)).
This property can be used as the source for data binding.
Implementation
public function get initialExtent():Extent
isInScaleRange:Boolean [read-only]
Returns true if the current scale of the map is between the maximum and minimum scale of the layer [added in version 1.3].
The comparison used maxScale <= map.scale <= minScale.
The map scale is rounded up when compared to maxScale
and rounded down when compared to minScale.
Implementation
public function get isInScaleRange():Boolean
loaded:Boolean [read-only]
When the layer is loaded, the value becomes "true" and layer properties can be accessed.
The load event is also fired. Subclasses must call setLoaded() to change this property.
This property can be used as the source for data binding.
Implementation
public function get loaded():Boolean
map:Map [read-only]
A reference to the Map this layer is in.
Implementation
public function get map():Map
public var maxScale:Number = 0
The maximum scale of the layer [added in version 1.3].
This property can be used as the source for data binding.
public var minScale:Number = 0
The minimum scale of the layer [added in version 1.3].
This property can be used as the source for data binding.
spatialReference:SpatialReference [read-only]
The spatial reference of the layer. Subclasses should override this method as a best practice in case a subclassed layer is added to a map which has a different spatial reference.
The default value is new SpatialReference(4326).
This property can be used as the source for data binding.
Implementation
public function get spatialReference():SpatialReference
units:String [read-only]
The units of the layer. Subclasses should override this method as a best practice in case a subclassed layer is added to a map which has different "units".
The default value is Units.DECIMAL_DEGREES.
This property can be used as the source for data binding.
Implementation
public function get units():String
See also
public function Layer()
Creates a new Layer object.
protected function addMapListeners():void
Adds listeners for ExtentEvent.EXTENT_CHANGE, ZoomEvent.ZOOM_START,
ZoomEvent.ZOOM_UPDATE and ZoomEvent.ZOOM_END.
See also
protected function extentChangeHandler(event:ExtentEvent):void
When an EXTENT_CHANGE event occurs, this calls invalidateLayer();
Parameters
protected function hideHandler(event:FlexEvent):void
When the layer is hidden (visible is set to false), this calls removeMapListeners().
Parameters
| event:FlexEvent — The FlexEvent that occurred.
|
protected function invalidateLayer():void
Subclasses should call this whenever they would like to have updateLayer() called on them. It's
analogous to Flex's invalidateDisplayList()/updateDisplayList() methods since many calls to
invalidateLayer() in one frame will only result in a single call to updateLayer() in the next
frame.
See also
public function refresh():void
Causes the layer to redraw or reload its content.
protected function removeAllChildren():void
Removes all the layers children.
protected function removeMapListeners():void
Removes the four event listeners added by addMapListeners();
protected function setLoaded(value:Boolean):void
Subclasses must call this when they've loaded all their properties and are ready to load
their content.
Parameters
| value:Boolean — Returns true if the layer is ready; false otherwise.
|
protected function showHandler(event:FlexEvent):void
When the layer is shown (visible is set to true), this calls addMapListeners() and invalidateLayer().
Parameters
| event:FlexEvent — The FlexEvent that occurred.
|
protected function toScreenX(mapX:Number):Number
Converts the x-coordinate of map point to a screen point.
Parameters
| mapX:Number — The x-coordinate of the map point to convert.
|
Returns
| Number — The x-coordinate in screen coordinates.
|
protected function toScreenY(mapY:Number):Number
Converts the y-coordinate of map point to a screen point.
Parameters
| mapY:Number — The y-coordinate of the map point to convert.
|
Returns
| Number — The y-coordinate in screen coordinates.
|
protected function updateLayer():void
Subclasses must override this method. It is called whenever the layer needs to be refreshed.
See also
protected function zoomEndHandler(event:ZoomEvent):void
Finishes the zoom animation.
Parameters
| event:ZoomEvent — The ZoomEvent that occurred.
|
protected function zoomStartHandler(event:ZoomEvent):void
Prepares the zoom animation by taking a bitmap of the layer.
Parameters
| event:ZoomEvent — The ZoomEvent that occurred.
|
protected function zoomUpdateHandler(event:ZoomEvent):void
Redraws the bitmap of the layer.
Parameters
| event:ZoomEvent — The ZoomEvent that occurred.
|
Event object type: com.esri.ags.events.LayerEvent
LayerEvent.type property = com.esri.ags.events.LayerEvent.LOAD
Fires after layer properties for the layer are successfully populated.
Defines the value of the type property of the event object for a load event.
Event object type: com.esri.ags.events.LayerEvent
LayerEvent.type property = com.esri.ags.events.LayerEvent.LOAD_ERROR
Fires if the layer is unable to load.
Defines the value of the type property of the event object for a loadError event.
(c) 2009 ESRI. All rights reserved.
mx.core.UIComponent