com.luciad.view.gxy.labeling

LuciadLightspeedClass TLcdGXYAsynchronousLabelPlacer

java.lang.Object

com.luciad.view.gxy.labeling.TLcdGXYAsynchronousLabelPlacer

All Implemented Interfaces:

ILcdCloneable, ILcdGXYViewLabelPlacer, Cloneable

public class TLcdGXYAsynchronousLabelPlacer
extends Object
implements ILcdGXYViewLabelPlacer

This view label placer can be used to perform asynchronous labeling. It tries to execute the label placing on the PaintQueue thread(s) and on a background thread. Because of this, the EventDispatch thread is never blocked during label placing. Asynchronous label placing can be enabled by adding this view label placer to the view.

Asynchronous label placing can be used in two cases :

• with asynchronous painting disabled : label placing is executed partly on the EventDispatch thread, and partly on a background thread. The consequence is that in this case asynchronous label placing still shows blocking behavior when it uses the EventDispatch thread.
• with asynchronous painting enabled : label placing is executed partly on the PaintQueue thread(s) and partly on a background thread. Because the EventDispatch thread is never used, label placing is non-blocking.

When using asynchronous labeling, thread-safety of the labeling algorithms should be kept in mind. Problems can occur if the ILcdGXYLabelingAlgorithm.collectLabelInfo implementation is not thread safe. When this is the case, an instance of the (non thread-safe) labeling algorithm should not be used on multiple threads. This is especially important when asynchronous painting is used, because in that case, the collecting method of the labeling algorithm can be executed on multiple PaintQueue threads.

When the collecting method of a labeling algorithm is thread-safe, they can be used on multiple threads without a problem. One should also make sure that when the collecting of labeling information is performed on multiple threads, the set priority provider is also thread-safe.

Note: When using this label placer in combination with asynchronous painting, it passes the wrapped layer to the labeling algorithm, and not the asynchronous layer wrapper.

Since:

10.1

Nested Class Summary

Nested classes/interfaces inherited from interface com.luciad.view.gxy.labeling.ILcdGXYViewLabelPlacer

ILcdGXYViewLabelPlacer.ViewLabelPlacerCallback

Constructor Summary

Constructors

Constructor and Description
TLcdGXYAsynchronousLabelPlacer() Create a new asynchronous label placer with a labeling algorithm that delegates to the appropriate layer's labeling algorithm.
TLcdGXYAsynchronousLabelPlacer(ILcdGXYLabelingAlgorithm aLabelingAlgorithm) Create a new asynchronous label placer using the given labeling algorithm.

Method Summary

Modifier and Type	Method and Description
void	addStatusListener(ILcdStatusListener aListener) Adds the given status listener to this view label placer.
Object	clone() Makes Object.clone() public.
ILcdLabelConflictChecker	getLabelConflictChecker() Returns the label conflict checker used when placing labels.
ILcdGXYLabelingAlgorithm	getLabelingAlgorithm() Returns the labeling algorithm used.
ILcdGXYLabelObstacleProvider	getLabelObstacleProvider() Returns the used ILcdGXYLabelObstacleProvider.
boolean	isBusyPlacing() Checks if the asynchronous label placer is busy label placing or if label placing is scheduled.
void	placeLabels(Graphics aGraphics, ILcdGXYView aGXYView, ILcdGXYViewLabelPlacer.ViewLabelPlacerCallback aCallback) The implementation of this method shall define how to place the labels of all objects in the various ILcdGXYLayers of the given ILcdGXYView.
void	placeLabels(Graphics aGraphics, List<ILcdGXYLayer> aGXYLayers, ILcdGXYView aGXYView, ILcdGXYViewLabelPlacer.ViewLabelPlacerCallback aCallback) The implementation of this method shall define how to place the labels of all objects in the various ILcdGXYLayers from the given List.
void	removeStatusListener(ILcdStatusListener aListener) Removes the given status listener from this view label placer.
void	setLabelConflictChecker(ILcdLabelConflictChecker aLabelConflictChecker) Sets the label conflict checker to be used when placing labels.
void	setLabelObstacleProvider(ILcdGXYLabelObstacleProvider aLabelObstacleProvider) Sets the used label obstacle provider.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TLcdGXYAsynchronousLabelPlacer

public TLcdGXYAsynchronousLabelPlacer()

Create a new asynchronous label placer with a labeling algorithm that delegates to the appropriate layer's labeling algorithm.

Since:

2020.0

TLcdGXYAsynchronousLabelPlacer

public TLcdGXYAsynchronousLabelPlacer(ILcdGXYLabelingAlgorithm aLabelingAlgorithm)

Create a new asynchronous label placer using the given labeling algorithm.

Warning: when calling this constructor you are overriding the the layer's own label algorithms.

Parameters:

aLabelingAlgorithm - a labeling algorithm.

Method Detail

getLabelingAlgorithm

public ILcdGXYLabelingAlgorithm getLabelingAlgorithm()

Returns the labeling algorithm used.

Returns:

the labeling algorithm.

getLabelConflictChecker

public ILcdLabelConflictChecker getLabelConflictChecker()

Returns the label conflict checker used when placing labels.

Returns:

the label conflict checker used when placing labels.

See Also:

setLabelConflictChecker

setLabelConflictChecker

public void setLabelConflictChecker(ILcdLabelConflictChecker aLabelConflictChecker)

Sets the label conflict checker to be used when placing labels.

Parameters:

aLabelConflictChecker - the label conflict checker to be used when placing labels.

See Also:

getLabelConflictChecker()

getLabelObstacleProvider

public ILcdGXYLabelObstacleProvider getLabelObstacleProvider()

Returns the used ILcdGXYLabelObstacleProvider.

Returns:

the used ILcdGXYLabelObstacleProvider, or null if no label obstacle provider is used.

See Also:

setLabelObstacleProvider(com.luciad.view.gxy.ILcdGXYLabelObstacleProvider)

setLabelObstacleProvider

public void setLabelObstacleProvider(ILcdGXYLabelObstacleProvider aLabelObstacleProvider)

Sets the used label obstacle provider. This obstacle provider is used to provide the labeling algorithm with obstacles: places where preferably no labels are placed.

The default value is null.

Parameters:

aLabelObstacleProvider - a label obstacle provider.

See Also:

getLabelObstacleProvider()

isBusyPlacing

public boolean isBusyPlacing()

Checks if the asynchronous label placer is busy label placing or if label placing is scheduled.

Returns:

true if the label placer is still label placing, and false otherwise.

clone

public Object clone()

Description copied from interface: ILcdCloneable

Makes Object.clone() public.

When for example extending from java.lang.Object, it can be implemented like this:

 public Object clone() {
   try {
     return super.clone();
   } catch ( CloneNotSupportedException e ) {
     // Cannot happen: extends from Object and implements Cloneable (see also Object.clone)
     throw new RuntimeException( e );
   }
 }
 

Specified by:

clone in interface ILcdCloneable

Overrides:

clone in class Object

See Also:

Object.clone()

addStatusListener

public void addStatusListener(ILcdStatusListener aListener)

Description copied from interface: ILcdGXYViewLabelPlacer

Adds the given status listener to this view label placer. Whenever an event occurs concerning the labeling process, this listener is notified.

Specified by:

addStatusListener in interface ILcdGXYViewLabelPlacer

Parameters:

aListener - a labeling listener.

removeStatusListener

public void removeStatusListener(ILcdStatusListener aListener)

Description copied from interface: ILcdGXYViewLabelPlacer

Removes the given status listener from this view label placer. After calling this method, the given listener will not be notified anymore.

Specified by:

removeStatusListener in interface ILcdGXYViewLabelPlacer

Parameters:

aListener - a labeling listener.

placeLabels

public void placeLabels(Graphics aGraphics,
                        ILcdGXYView aGXYView,
                        ILcdGXYViewLabelPlacer.ViewLabelPlacerCallback aCallback)

Description copied from interface: ILcdGXYViewLabelPlacer

The implementation of this method shall define how to place the labels of all objects in the various ILcdGXYLayers of the given ILcdGXYView. Here one can implement or use various smart algorithms to check whether or not to place a label at a certain location.

Layers for which labels are placed should be ILcdGXYEditableLabelsLayers. This method should then inform the ALcdLabelLocations associated with that layer which labels were placed, and where they were placed.

This method should only be called once every time the view is invalidated.

Specified by:

placeLabels in interface ILcdGXYViewLabelPlacer

Parameters:

aGraphics - The current Graphics instance.

aGXYView - The view for which to place the labels.

aCallback - Will be invoked when labels are updated, and when the label placing has ended.

See Also:

ILcdGXYEditableLabelsLayer, ALcdLabelLocations.putLabelLocation(java.lang.Object, int, int, com.luciad.view.ILcdView, com.luciad.view.TLcdLabelLocation, int), ALcdLabelLocations.setPainted(java.lang.Object, int, int, com.luciad.view.ILcdView, boolean, int)

placeLabels

public void placeLabels(Graphics aGraphics,
                        List<ILcdGXYLayer> aGXYLayers,
                        ILcdGXYView aGXYView,
                        ILcdGXYViewLabelPlacer.ViewLabelPlacerCallback aCallback)

Description copied from interface: ILcdGXYViewLabelPlacer

The implementation of this method shall define how to place the labels of all objects in the various ILcdGXYLayers from the given List. Here one can implement or use various smart algorithms to check whether or not to place a label at a certain location.

Layers for which labels are placed should be ILcdGXYEditableLabelsLayers. This method should then inform the ALcdLabelLocations associated with that layer which labels were placed, and where they were placed.

This method should only be called once every time the view is invalidated.

Specified by:

placeLabels in interface ILcdGXYViewLabelPlacer

Parameters:

aGraphics - The current Graphics instance.

aGXYLayers - Only the labels for the layers in this List will be placed.

aGXYView - The view for which to place the labels.

aCallback - Will be invoked when labels are updated, and when the label placing has ended.

See Also:

ILcdGXYEditableLabelsLayer, ALcdLabelLocations.putLabelLocation(java.lang.Object, int, int, com.luciad.view.ILcdView, com.luciad.view.TLcdLabelLocation, int), ALcdLabelLocations.setPainted(java.lang.Object, int, int, com.luciad.view.ILcdView, boolean, int)