Package com.luciad.view.gxy.labeling.algorithm.discrete

Class TLcdGXYLocationListLabelingAlgorithm

java.lang.Object

com.luciad.view.gxy.labeling.algorithm.discrete.ALcdGXYDiscretePlacementsLabelingAlgorithm

com.luciad.view.gxy.labeling.algorithm.discrete.TLcdGXYLocationListLabelingAlgorithm

All Implemented Interfaces:

ILcdCloneable, ILcdGXYLabelingAlgorithm, Cloneable

public class TLcdGXYLocationListLabelingAlgorithm
extends ALcdGXYDiscretePlacementsLabelingAlgorithm

This labeling is a greedy labeling algorithm that uses free placement (see ILcdGXYLabelPainter2) to determine label locations. It tries to place labels in the order provided by the input TLcdCollectedLabelInfoList object (see TLcdCollectedLabelInfoList.getLabels()). It tries to place the labels one by one, and when a label cannot be placed without overlap, it is omitted.

This algorithm uses free placements to determine the location and bounds of the labels. So this algorithm gives full control over where labels are actually placed. This labeling algorithm can be extended to provide custom locations for a label. To do this, 2 methods need to be overridden :

• getMaxLocationCount() : Override this method to set the number of locations that are tried for a label.
• getLocationBounds() : Override this method to return label bounds associated with a location. This method should be able to return getMaxLocationCount bounds.

After retrieving bounds for a label position, the returned bounds are converted to a TLcdLabelLocation. One of these label location is eventually chosen for the label.

The default implementations of these methods use the following methods : getLocationList() and getShiftLabelLocation(). So the default behavior of this class can be customized by using setLocationList(Location[]) and setShiftLabelLocation(int). When overriding getMaxLocationCount() and getLocationBounds(), getLocationList() and getShiftLabelLocation() will not be used anymore.

This algorithm also uses a forced painting threshold priority to force labels to be placed, even if they overlap with other labels, see setForcedPaintingThresholdPriority(int).

The used label painter must be an ILcdGXYLabelPainter2. If not, labels will be painted at an incorrect location.

The implementation of this labeling algorithm is thread-safe.

Since:

10.1

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	TLcdGXYLocationListLabelingAlgorithm.Location

Constructor Summary

Constructors

Constructor	Description
TLcdGXYLocationListLabelingAlgorithm()

Method Summary

Modifier and Type	Method	Description
TLcdGXYLocationListLabelingAlgorithm	clone()	Makes Object.clone() public.
TLcdCollectedLabelInfoList	collectLabelInfo(List<TLcdLabelIdentifier> aLabelsToCollect, Graphics aGraphics, ILcdGXYView aGXYView)	This method returns a TLcdCollectedLabelInfoList object based on the given list of TLcdLabelIdentifiers.
protected Iterator<TLcdCollectedLabelInfo>	createLabelIterator(TLcdCollectedLabelInfoList aLabelInfoList, ILcdLabelConflictChecker aBoundsConflictChecker, ILcdGXYView aView)	Creates a new Iterator that iterates over the TLcdCollectedLabelInfos.
protected ILcdLabelPlacementEvaluator	createLabelPlacementEvaluator(TLcdCollectedLabelInfoList aLabelInfoList, ILcdLabelConflictChecker aBoundsConflictChecker, ILcdGXYView aView)	Creates a new ILcdLabelPlacementEvaluator using the given parameters.
protected Iterator<TLcdLabelPlacement>	createLabelPlacementIterator(TLcdCollectedLabelInfo aLabel, TLcdCollectedLabelInfoList aLabelInfoList, ILcdLabelConflictChecker aBoundsConflictChecker, ILcdGXYView aView)	Creates a new Iterator that iterates over the TLcdLabelPlacements for the given label.
int	getForcedPaintingThresholdPriority()	Returns the threshold priority for forced label painting.
ILcdGXYMultiLabelPriorityProvider	getLabelPriorityProvider()	Returns the label placing priority provider.
protected double	getLocationBounds(TLcdCollectedLabelInfo aLabelInfo, int aLocationIndex, TLcdCollectedLabelInfoList aLabelInfoList, Rectangle aBoundsSFCT)	This method calculates the bounds for the given label using the given location index.
TLcdGXYLocationListLabelingAlgorithm.Location[]	getLocationList()	Returns the list of possible locations to place the labels.
protected int	getMaxLocationCount(TLcdCollectedLabelInfo aLabelInfo, TLcdCollectedLabelInfoList aLabelInfoList)	Returns the maximal number of locations to be tried for the given label.
int	getShiftLabelLocation()	Returns how many pixels the label must be removed from the anchor point of the domain object.
void	setForcedPaintingThresholdPriority(int aPriority)	Sets the threshold priority for forced label painting.
void	setLabelPriorityProvider(ILcdGXYMultiLabelPriorityProvider aLabelPriorityProvider)	Sets the label placing priority provider, specifying the priority for individual labels.
void	setLocationList(TLcdGXYLocationListLabelingAlgorithm.Location[] aLocationList)	Sets a new location list.
void	setShiftLabelLocation(int aShift)	Sets how many pixels the label must be removed from the anchor point of the domain object.

Methods inherited from class com.luciad.view.gxy.labeling.algorithm.discrete.ALcdGXYDiscretePlacementsLabelingAlgorithm

computeLabelPlacements

Methods inherited from class java.lang.Object

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

Constructor Details

TLcdGXYLocationListLabelingAlgorithm

public TLcdGXYLocationListLabelingAlgorithm()

Method Details

clone

public TLcdGXYLocationListLabelingAlgorithm 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 ALcdGXYDiscretePlacementsLabelingAlgorithm

See Also:

• Object.clone()

setForcedPaintingThresholdPriority

public void setForcedPaintingThresholdPriority(int aPriority)

Sets the threshold priority for forced label painting. The labels of objects with a priority value less than or equal to the threshold priority value will always be painted, even if the labeling algorithm could not find any suitable place for the label. This makes it possible for labels to overlap. The default value is -1, in which case no forced painting is done.

Parameters:

aPriority - the threshold priority for forced label painting.

See Also:

• getForcedPaintingThresholdPriority()

getForcedPaintingThresholdPriority

public int getForcedPaintingThresholdPriority()

Returns the threshold priority for forced label painting.

Returns:

the threshold priority for forced label painting.

See Also:

• setForcedPaintingThresholdPriority(int)

getLabelPriorityProvider

public ILcdGXYMultiLabelPriorityProvider getLabelPriorityProvider()

Returns the label placing priority provider.

Returns:

the label placing priority provider.

See Also:

• setLabelPriorityProvider(com.luciad.view.gxy.ILcdGXYMultiLabelPriorityProvider)

setLabelPriorityProvider

public void setLabelPriorityProvider(ILcdGXYMultiLabelPriorityProvider aLabelPriorityProvider)

Sets the label placing priority provider, specifying the priority for individual labels. This priority provider specifies the order in which labels are placed. In the event labels overlap, those with higher priority are painted on top of labels with lower priority. So lower priority labels are the first candidates if labels need to be obscured.

When no label priority provider is set, a default label priority provider is used which returns Integer.MAX_VALUE for all labels.

The priority provider is used to sort the list of labels before their placements are computed.

Parameters:

aLabelPriorityProvider - The priority provider to set.

getMaxLocationCount

protected int getMaxLocationCount(TLcdCollectedLabelInfo aLabelInfo,
 TLcdCollectedLabelInfoList aLabelInfoList)

Returns the maximal number of locations to be tried for the given label. Override this method to return a custom number of locations. When overriding this method, one should also make sure that the getLocationBounds method can create the same number of location bounds as returned by this method.

The default implementation uses the length of the array returned by getLocationList().

Parameters:

aLabelInfo - the label for which the maximum placement count is returned.

aLabelInfoList - the label infos object.

Returns:

the maximal number of placements to be tried.

getLocationBounds

protected double getLocationBounds(TLcdCollectedLabelInfo aLabelInfo,
 int aLocationIndex,
 TLcdCollectedLabelInfoList aLabelInfoList,
 Rectangle aBoundsSFCT)
                            throws IllegalArgumentException

This method calculates the bounds for the given label using the given location index. Override this method to create custom bounds for a label.

The default implementation of this method uses the positions returned by getLocationList(), combined with the offset retrieved by getShiftLabelLocation().

Parameters:

aLabelInfo - the label for which placement bounds are calculated.

aLocationIndex - the placement index.

aLabelInfoList - the label infos object.

aBoundsSFCT - the bounds to be initialized.

Returns:

the rotation of the bounds.

Throws:

IllegalArgumentException - this exception can be thrown when certain data to calculate the bounds is not available.

setLocationList

public void setLocationList(TLcdGXYLocationListLabelingAlgorithm.Location[] aLocationList)

Sets a new location list.

This method is used by the default implementation of getLocationBounds. By default, all TLcdGXYLocationListLabelingAlgorithm.Location values are offered.

Parameters:

aLocationList - the list of possible locations to place the labels.

See Also:

• getLocationList()
• getLocationBounds
• getMaxLocationCount

getLocationList

public TLcdGXYLocationListLabelingAlgorithm.Location[] getLocationList()

Returns the list of possible locations to place the labels.

By default this method returns an array containing

• TLcdGXYLocationListLabelingAlgorithm.Location.SOUTH_EAST.
• TLcdGXYLocationListLabelingAlgorithm.Location.NORTH_WEST.
• TLcdGXYLocationListLabelingAlgorithm.Location.NORTH_EAST.
• TLcdGXYLocationListLabelingAlgorithm.Location.SOUTH_WEST.
• TLcdGXYLocationListLabelingAlgorithm.Location.EAST.
• TLcdGXYLocationListLabelingAlgorithm.Location.WEST.
• TLcdGXYLocationListLabelingAlgorithm.Location.NORTH.
• TLcdGXYLocationListLabelingAlgorithm.Location.SOUTH.
• TLcdGXYLocationListLabelingAlgorithm.Location.CENTER.

This method is used by the default implementation of getLocationBounds.

Returns:

the list of possible locations to place the labels.

See Also:

• setLocationList(com.luciad.view.gxy.labeling.algorithm.discrete.TLcdGXYLocationListLabelingAlgorithm.Location[])
• getLocationBounds
• getMaxLocationCount

setShiftLabelLocation

public void setShiftLabelLocation(int aShift)

Sets how many pixels the label must be removed from the anchor point of the domain object. If the location of the label is east or west, this shift is applied in horizontal direction; if the location is north or south, this shift is applied in vertical direction. In case of north east, south east, south west or north west, this shift is applied in both directions. If the location of the label is center, the shift is ignored.

The default for this value is 4 pixels.

This method is used by the default implementation of getLocationBounds.

Parameters:

aShift - the distance, expressed in pixels, that the label must be removed from the domain object.

See Also:

• getShiftLabelLocation()
• getLocationBounds

getShiftLabelLocation

public int getShiftLabelLocation()

Returns how many pixels the label must be removed from the anchor point of the domain object.

This method is used by the default implementation of getLocationBounds.

Returns:

the distance, expressed in pixels, that the label must be removed from the domain object.

See Also:

• setShiftLabelLocation(int)
• getLocationBounds

collectLabelInfo

public TLcdCollectedLabelInfoList collectLabelInfo(List<TLcdLabelIdentifier> aLabelsToCollect,
 Graphics aGraphics,
 ILcdGXYView aGXYView)

Description copied from interface: ILcdGXYLabelingAlgorithm

This method returns a TLcdCollectedLabelInfoList object based on the given list of TLcdLabelIdentifiers. The returned TLcdCollectedLabelInfoList should contain a TLcdCollectedLabelInfo object for each label that should be placed.

Each TLcdCollectedLabelInfo should also contain all information needed by computeLabelPlacements to place the labels. In order to enable correct asynchronous label placing, all calls to the layer and the (label) painters should be done in this method. The results should then be stored in the info objects.

It is possible that the returned TLcdCollectedLabelInfoList doesn't contain a TLcdCollectedLabelInfo object for every given TLcdLabelIdentifier. In that case the missing labels are not placed.

Specified by:

collectLabelInfo in interface ILcdGXYLabelingAlgorithm

Parameters:

aLabelsToCollect - the labels for which a TLcdCollectedLabelInfoList should be created.

aGraphics - the graphics.

aGXYView - the view.

Returns:

a TLcdCollectedLabelInfoList which contains all the information needed to place the labels.

createLabelIterator

protected Iterator<TLcdCollectedLabelInfo> createLabelIterator(TLcdCollectedLabelInfoList aLabelInfoList,
 ILcdLabelConflictChecker aBoundsConflictChecker,
 ILcdGXYView aView)

Description copied from class: ALcdGXYDiscretePlacementsLabelingAlgorithm

Creates a new Iterator that iterates over the TLcdCollectedLabelInfos. The abstract labeling algorithm will continue iterating over TLcdCollectedLabelInfos as long as Iterator.hasNext() returns true. When it returns false, no more labels will be tried, and computeLabelPlacements returns. Iterator.hasNext() should always be called before calling Iterator.next(), and if it returns true, Iterator.next() should never return null.

The implementation of this method should be as independent as possible. It should not rely on createLabelPlacementIterator or createLabelPlacementEvaluator. Not respecting this might result in unexpected behaviour when wrapping or extending this class.

The returned TLcdCollectedLabelInfo should be correctly initialized, i.e. it should contain all information needed to create valid TLcdLabelPlacements using createLabelPlacementIterator. It should also always point to its corresponding TLcdCollectedLabeledObjectInfo.

Override this method to provide a custom implementation.

Specified by:

createLabelIterator in class ALcdGXYDiscretePlacementsLabelingAlgorithm

Parameters:

aLabelInfoList - the label infos object that contains all information needed to place the labels.

aBoundsConflictChecker - the bounds conflict checker to be used when evaluating label placements.

aView - the view.

Returns:

a new Iterator that iterates over TLcdCollectedLabelInfos.

createLabelPlacementIterator

protected Iterator<TLcdLabelPlacement> createLabelPlacementIterator(TLcdCollectedLabelInfo aLabel,
 TLcdCollectedLabelInfoList aLabelInfoList,
 ILcdLabelConflictChecker aBoundsConflictChecker,
 ILcdGXYView aView)

Description copied from class: ALcdGXYDiscretePlacementsLabelingAlgorithm

Creates a new Iterator that iterates over the TLcdLabelPlacements for the given label. The abstract labeling algorithm will continue iterating over TLcdLabelPlacements as long as Iterator.hasNext() returns true. When it returns false, a new label will be tried. Iterator.hasNext() should always be called before calling Iterator.next(), and if it returns true, Iterator.next() should never return null.

The implementation of this method should be as independent as possible. It should not rely on createLabelIterator or createLabelPlacementEvaluator. Not respecting this might result in unexpected behaviour when wrapping or extending this class.

The returned TLcdLabelPlacement should be correctly initialized, i.e. it should at least be able to return a valid label location, bounds rectangle and bounds rotation. It should also reference its corresponding TLcdCollectedLabelInfo.

Override this method to provide a custom implementation.

Specified by:

createLabelPlacementIterator in class ALcdGXYDiscretePlacementsLabelingAlgorithm

Parameters:

aLabel - the label for which an iterator should be created.

aLabelInfoList - the info object that contains all information needed to place the labels.

aBoundsConflictChecker - the bounds conflict checker to be used when evaluating label placements.

aView - the view.

Returns:

a new Iterator that iterates over TLcdLabelPlacements.

createLabelPlacementEvaluator

protected ILcdLabelPlacementEvaluator createLabelPlacementEvaluator(TLcdCollectedLabelInfoList aLabelInfoList,
 ILcdLabelConflictChecker aBoundsConflictChecker,
 ILcdGXYView aView)

Description copied from class: ALcdGXYDiscretePlacementsLabelingAlgorithm

Creates a new ILcdLabelPlacementEvaluator using the given parameters. It evaluates the placements returned by createLabelPlacementIterator, and returns a PlacementResult to denote if the placement should be used for its label or not.

The following actions are undertaken for the following placement results :

• PlacementResult.SUCCESS : the given label placement will be used for its label, it will be added to the list of placed labels, and it will be added to the given ILcdLabelConflictChecker. After that, ILcdLabelPlacementEvaluator.placementApplied will be called and no more placements are tried for the label.
• PlacementResult.FALLBACK : the abstract algorithm will try to find an other placements which returns PlacementResult.SUCCESS. When no such placement is found, this placement will be added to the list of placed labels, and it will be added to the given ILcdLabelConflictChecker. After that, ILcdLabelPlacementEvaluator.placementApplied will be called.
• PlacementResult.TRY_NEW_PLACEMENT : the abstract algorithm will try to find an other placement which returns PlacementResult.SUCCESS or PlacementResult.FALLBACK. When no such placement is found, ILcdLabelPlacementEvaluator.noPlacementApplied is called.
• PlacementResult.FAILED : the abstract algorithm will immediately call ILcdLabelPlacementEvaluator.noPlacementApplied and will not try to find other placements for the label.

Override this method to provide a custom implementation.

Specified by:

createLabelPlacementEvaluator in class ALcdGXYDiscretePlacementsLabelingAlgorithm

Parameters:

aLabelInfoList - the info object that contains all information needed to place the labels.

aBoundsConflictChecker - the bounds conflict checker to be used when evaluating label placements.

aView - the view

Returns:

a new LabelPlacementEvaluator

See Also:

• ILcdLabelPlacementEvaluator