Layer (Geotools modules 21.0 API)

Object
- Layer

Direct Known Subclasses:

DirectLayer, StyleLayer
```
public abstract class Layer
extends Object
```
A Layer to be rendered.
Layers usually represent a single dataset; and arranged into a z-order by a Map for display.

Since:

2.7

Field Summary

Fields
Modifier and Type	Field and Description
`protected CopyOnWriteArrayList<MapLayerListener>`	`listenerList` Listeners to be notified when layer contents change.
`protected static Logger`	`LOGGER` The logger for the map module.
`protected boolean`	`selected` Flag to mark the layer as selected (for general use by clients)
`protected String`	`title` Human readable title for the layer.
`protected Map<String,Object>`	`userData` Map of application supplied information.
`protected boolean`	`visible` Flag to mark the layer as visible when being rendered

Constructor Summary

Constructors
Modifier Constructor and Description

protected Layer()
Layer creation; please use a concrete subclass to work with specific content.

Constructors
Modifier	Constructor and Description
`protected`	`Layer()` Layer creation; please use a concrete subclass to work with specific content.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addMapLayerListener(MapLayerListener listener)` The listener is notified when the layer information changes; or when the contents of the layer changes.
`protected void`	`connectDataListener(boolean listen)` Called in an interactive environment where a Layer is expected to listen to the data source on behalf of the application.
`void`	`dispose()` Allows a Layer to clean up any listeners, or internal caches or resources it has added during use.
`protected void`	`finalize()`
`protected void`	`fireMapLayerListenerLayerChanged(int eventType)` Notifies all registered listeners about the event.
`protected void`	`fireMapLayerListenerLayerDeselected()` Notifies all registered listeners about the deselection event.
`protected void`	`fireMapLayerListenerLayerHidden()` Notifies all registered listeners about the event.
`protected void`	`fireMapLayerListenerLayerPreDispose()` Notifies all registered listeners that the layer is scheduled to be disposed.
`protected void`	`fireMapLayerListenerLayerSelected()` Notifies all registered listeners about the selection event.
`protected void`	`fireMapLayerListenerLayerShown()` Notifies all registered listeners about the event.
`abstract ReferencedEnvelope`	`getBounds()` The bounds of the Layer content (if known).
`FeatureSource<?,?>`	`getFeatureSource()` Used to access the feature collection for this layer; if available.
`Query`	`getQuery()` The definition query (including filter) for this layer, or `Query.ALL` if no definition query has been provided by the user.
`Style`	`getStyle()` Get the style for this layer.
`String`	`getTitle()` Get the title of this layer.
`Map<String,Object>`	`getUserData()` Application supplied information; may be used as a scatch pad for information such selection.
`boolean`	`isSelected()` Determines whether this layer is selected.
`boolean`	`isVisible()` Determines whether this layer is visible or hidden.
`void`	`preDispose()` Alerts listeners that this layer has been scheduled to be disposed to give them a chance to finish or cancel any tasks using the layer.
`void`	`removeMapLayerListener(MapLayerListener listener)` Removes a listener from the listener list for this layer.
`void`	`setSelected(boolean selected)` Sets layer selection status.
`void`	`setTitle(String title)` Set the title of this layer.
`void`	`setVisible(boolean visible)` Sets whether the layer is to be shown or hidden when rendering.
`String`	`toString()`

Methods inherited from class Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - LOGGER
```
protected static final Logger LOGGER
```
    The logger for the map module.
  - title
```
protected String title
```
    Human readable title for the layer.
  - visible
```
protected boolean visible
```
    Flag to mark the layer as visible when being rendered
  - selected
```
protected boolean selected
```
    Flag to mark the layer as selected (for general use by clients)
  - userData
```
protected Map<String,Object> userData
```
    Map of application supplied information.
  - listenerList
```
protected CopyOnWriteArrayList<MapLayerListener> listenerList
```
    Listeners to be notified when layer contents change.
- Constructor Detail
  - Layer
```
protected Layer()
```
    Layer creation; please use a concrete subclass to work with specific content.
    Note you should dispose() a layer after use.
- Method Detail
  - fireMapLayerListenerLayerChanged
```
protected void fireMapLayerListenerLayerChanged(int eventType)
```
    Notifies all registered listeners about the event.
    
    Parameters:
    
    event - The event to be fired
  - fireMapLayerListenerLayerShown
```
protected void fireMapLayerListenerLayerShown()
```
    Notifies all registered listeners about the event.
    
    Parameters:
    
    event - The event to be fired
  - fireMapLayerListenerLayerHidden
```
protected void fireMapLayerListenerLayerHidden()
```
    Notifies all registered listeners about the event.
    
    Parameters:
    
    event - The event to be fired
  - fireMapLayerListenerLayerSelected
```
protected void fireMapLayerListenerLayerSelected()
```
    Notifies all registered listeners about the selection event.
    
    Parameters:
    
    event - The event to be fired
  - fireMapLayerListenerLayerDeselected
```
protected void fireMapLayerListenerLayerDeselected()
```
    Notifies all registered listeners about the deselection event.
    
    Parameters:
    
    event - The event to be fired
  - fireMapLayerListenerLayerPreDispose
```
protected void fireMapLayerListenerLayerPreDispose()
```
    Notifies all registered listeners that the layer is scheduled to be disposed.
    
    Parameters:
    
    event - The event to be fired
  - finalize
```
protected void finalize()
                 throws Throwable
```
    Overrides:
    
    finalize in class Object
    
    Throws:
    
    Throwable
  - preDispose
```
public void preDispose()
```
    Alerts listeners that this layer has been scheduled to be disposed to give them a chance to finish or cancel any tasks using the layer.
  - dispose
```
public void dispose()
```
    Allows a Layer to clean up any listeners, or internal caches or resources it has added during use.
  - getTitle
```
public String getTitle()
```
    Get the title of this layer. If title has not been defined then an empty string is returned.
    
    Returns:
    
    The title of this layer.
  - setTitle
```
public void setTitle(String title)
```
    Set the title of this layer. A LayerEvent is fired if the new title is different from the previous one.
    
    Parameters:
    
    title - The title of this layer.
  - isVisible
```
public boolean isVisible()
```
    Determines whether this layer is visible or hidden.
    
    Returns:
    
    true if the layer is visible, or false if hidden
  - setVisible
```
public void setVisible(boolean visible)
```
    Sets whether the layer is to be shown or hidden when rendering. LayerEvent is fired if the visibility changed.
    
    Parameters:
    
    visible - true to show the layer; false to hide it
  - isSelected
```
public boolean isSelected()
```
    Determines whether this layer is selected. Selection status can be used by clients such as JMapPane for selective processing of layers.
    
    Returns:
    
    true if the layer is selected, or false otherwise
  - setSelected
```
public void setSelected(boolean selected)
```
    Sets layer selection status. This can be used by clients such as JMapPane for selective processing of layers.
    
    Parameters:
    
    selected - new selection status.
  - getUserData
```
public Map<String,Object> getUserData()
```
    Application supplied information; may be used as a scatch pad for information such selection.
    Example:
```
 layer.getUserData().put("selectable", true)
 
```
    Returns:
    
    Application parameters
  - getBounds
```
public abstract ReferencedEnvelope getBounds()
```
    The bounds of the Layer content (if known). The bounds can be used to determine if any of the layers content is "on screen" when rendering the map; however often it is expensive to calculate a layers bounds up front so we are allowing this value to be optional.
    The returned bounds are a ReferencedEnvelope using the same CoordinateReferenceSystem as the layers contents.
    
    Returns:
    
    layer bounds, null if unknown
  - addMapLayerListener
```
public void addMapLayerListener(MapLayerListener listener)
```
    The listener is notified when the layer information changes; or when the contents of the layer changes. This is used by interactive map displays to detect when information is modified and needs to be redrawn.
    
    Parameters:
    
    listener - The listener to add to the listener list.
  - removeMapLayerListener
```
public void removeMapLayerListener(MapLayerListener listener)
```
    Removes a listener from the listener list for this layer.
    
    Parameters:
    
    listener - The listener to remove from the listener list.
  - connectDataListener
```
protected void connectDataListener(boolean listen)
```
    Called in an interactive environment where a Layer is expected to listen to the data source on behalf of the application.
    This method is called as needed by addMapListener and removeMapListener to allow subclasses to connect any data listeners required in order to issue fireMapLayerChanged events.
    
    Parameters:
    
    listen - true to connect, false to disconnect
  - getStyle
```
public Style getStyle()
```
    Get the style for this layer. If style has not been set, then null is returned.
    This is an optional method that is used to support feature based rendering systems such as as KML.
    Please note that feature based renders can be very flexible; as an example raster content is asked to return the outline of each raster - in the event that the user has supplied a style drawing the raster as a Polygon outlines.
    
    Returns:
    
    The style (SLD).
  - getFeatureSource
```
public FeatureSource<?,?> getFeatureSource()
```
    Used to access the feature collection for this layer; if available.
    This is an optional method that is used to support feature based rendering systems such as as KML.
    Please note that feature based renders can be very flexible; as an example raster content is asked to return the outline of each raster - in the event that the user has supplied a style drawing the raster as a Polygon outlines.
    Override: Implementors should override this method to provide access to a feature representation of the layer contents if available. For DirectLayers displaying abstract concepts like a scale bar this may not be possible (however for some that display a grid this may in fact be possible).
    
    Returns:
    
    The features for this layer, or an an empty ArrayFeatureSource if not available.
  - getQuery
```
public Query getQuery()
```
    The definition query (including filter) for this layer, or Query.ALL if no definition query has been provided by the user.
    This is an optional method that is used to support feature based rendering systems such as as KML.
    Please note that feature based renders can be very flexible; as an example raster content is asked to return the outline of each raster - in the event that the user has supplied a style drawing the raster as a Polygon outlines.
    Implementors should take care to return a copy of their internal Query to be safe from modificaiton:
```
 if( query == null || query == Query.ALL ){
     return Query.ALL;
 }
 else {
     return new Query( query );
 }
 
```
    Returns:
    
    the definition query established for this layer. If not set, just returns Query.ALL, if set, returns a copy of the actual query object to avoid external modification
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class Layer

Field Summary

Constructor Summary

Method Summary

Methods inherited from class Object

Field Detail

LOGGER

title

visible

selected

userData

listenerList

Constructor Detail

Layer

Method Detail

fireMapLayerListenerLayerChanged

fireMapLayerListenerLayerShown

fireMapLayerListenerLayerHidden

fireMapLayerListenerLayerSelected

fireMapLayerListenerLayerDeselected

fireMapLayerListenerLayerPreDispose

finalize

preDispose

dispose

getTitle

setTitle

isVisible

setVisible

isSelected

setSelected

getUserData

getBounds

addMapLayerListener

removeMapLayerListener

connectDataListener

getStyle

getFeatureSource

getQuery

toString