Package com.luciad.view.lightspeed.label.algorithm.discrete

Class TLspInPathLabelingAlgorithm

java.lang.Object
com.luciad.view.lightspeed.label.algorithm.discrete.ALspDiscreteLabelingAlgorithm
com.luciad.view.lightspeed.label.algorithm.discrete.TLspInPathLabelingAlgorithm
All Implemented Interfaces:
ILcdCloneable, ILspLabelingAlgorithm, Cloneable
public class TLspInPathLabelingAlgorithm extends ALspDiscreteLabelingAlgorithm

Labeling algorithm that tries to place labels inside a path and keeps them inside the view. This algorithm checks the painted paths that are within the view and tries to add labels to them. These are located within the area defined by the path. This algorithm is typically used for placing labels for polygons or other closed shapes.

Note that this implementation does not support "holes" in paths.

The used label painter must be an ILspStampLocationLabelPainter. If not, the label will not be placed. The placed label location will be a TLspStampLabelLocation.

This algorithm has a computational overhead because it keeps the label inside the view. In order to use a faster algorithm, that doesn't keep the label inside the view, TLspFixedInPathLabelLocationProvider can be used.

Since:
2012.0

  • Constructor Details

    • TLspInPathLabelingAlgorithm

      public TLspInPathLabelingAlgorithm()
      Creates a new TLspInPathLabelingAlgorithm that can be used to place labels inside paths. These paths are created by a default path provider that discretizes the anchor of a label (see ILspLabelPainter.getAnchorObject) or the domain object if no anchor is defined explicitly.

  • Method Details

    • setQuality

      public void setQuality(double aQuality)
      Description copied from class: ALspDiscreteLabelingAlgorithm

      Sets the quality. If the quality setting is high, the algorithm will try to place more labels. If it is low, the algorithm will only try to place a small portion of the labels, making label placement faster. Setting the quality to e.g. 0.5 can dramatically improve the label placement performance in some cases.

      E.g. it is possible that due to the quality setting, this algorithm will only try to place 10% of the labels. This may still result in high quality results, but this depends on the used data. In general, using a lower quality setting will still work well when the data (and its labels) are distributed uniformly over the screen.

      By default, the quality is set to 1.0.

      Specified by:
      setQuality in class ALspDiscreteLabelingAlgorithm
      Parameters:
      aQuality - the new quality. This is a number in [0, 1].
      See Also:

    • getQuality

      public double getQuality()
      Description copied from class: ALspDiscreteLabelingAlgorithm
      Returns the quality setting.
      Specified by:
      getQuality in class ALspDiscreteLabelingAlgorithm
      Returns:
      the quality setting.
      See Also:

    • isReusePreviousLocations

      public boolean isReusePreviousLocations()
      Returns if this algorithm reuses the previous label locations.
      Returns:
      true if this algorithm reuses the previous label locations.
      See Also:

    • setReusePreviousLocations

      public void setReusePreviousLocations(boolean aReusePreviousLocations)
      When set to true, this algorithm will try to reuse the previous label locations. Reusing previous label locations causes the labels to be more stable, i.e. labels don't always move when for example the view is panned, or when objects are selected. This is because label positions are only recalculated when the previous label location has become invalid.

      The default value is true.

      Parameters:
      aReusePreviousLocations - true to enable reusing previous label locations, and false to disable it.
      See Also:

    • getMinimumPathLength

      public double getMinimumPathLength()
      Returns the minimum contour length for a clipped polygon to contain a label.
      Returns:
      the minimum contour length for a clipped polygon to contain a label.
      See Also:

    • setMinimumPathLength

      public void setMinimumPathLength(double aMinimumPathLength)
      Sets the minimum outline length for a clipped polygon to contain a label. This length is expressed in pixels and should be positive. When a clipped polygon has an outline length smaller than the given length, no label will be placed.

      The default value is 0 pixels, i.e. no clipped polygon will be excluded.

      Parameters:
      aMinimumPathLength - the minimal length for a clipped polygon to contain a label.

    • setClipEdgeOffsets

      public void setClipEdgeOffsets(int aLeftOffset, int aRightOffset, int aBottomOffset, int aTopOffset)
      Calling this methods lets you define a clipping rectangle within the view. This labeling algorithm will then try to keep the labels inside this clipping rectangle. By default, all offsets are 0, meaning that the clipping rectangle is the same as the view rectangle.
      Parameters:
      aLeftOffset - the offset from the left edge of the view
      aRightOffset - the offset from the right edge of the view
      aBottomOffset - the offset from the bottom edge of the view
      aTopOffset - the offset from the top edge of the view
      Since:
      2018.0

    • clone

      public TLspInPathLabelingAlgorithm 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 ALspDiscreteLabelingAlgorithm
      See Also:

    • createLabelIterator

      protected Iterator<TLspLabelID> createLabelIterator(List<TLspLabelID> aLabels, ILspLabelingAlgorithm.LabelContext aLabelContext, ILspLabelConflictChecker aConflictChecker, ILspView aView)
      Description copied from class: ALspDiscreteLabelingAlgorithm
      Creates a new Iterator that iterates over the TLspLabelIDs. The abstract algorithm will continue iterating over TLspLabelIDs as long as Iterator.hasNext() returns true. When it returns false, no more label placements will be tried, and placeLabels 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.

      Override this method to provide a custom implementation.

      Specified by:
      createLabelIterator in class ALspDiscreteLabelingAlgorithm
      Parameters:
      aLabels - a list of labels that need to be placed.
      aLabelContext - the label info object.
      aConflictChecker - the conflict checker to be used when evaluating placements.
      aView - the view.
      Returns:
      a new Iterator that iterates over TLspLabelIDs.

    • createLabelPlacementIterator

      protected Iterator<TLspLabelPlacement> createLabelPlacementIterator(TLspLabelID aLabel, ALspLabelLocations aCurrentLabelLocations, ILspLabelingAlgorithm.LabelContext aLabelContext, ILspLabelConflictChecker aConflictChecker, ILspView aView)
      Description copied from class: ALspDiscreteLabelingAlgorithm
      Creates a new Iterator that iterates over the TLspLabelPlacements for the given label. The abstract algorithm will continue iterating over TLspLabelPlacements 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 TLspLabelPlacement should be correctly initialized, that is it should at least be able to return a valid label location, bounds rectangle and bounds rotation. It should also reference its corresponding TLspLabelID.

      Override this method to provide a custom implementation.

      Specified by:
      createLabelPlacementIterator in class ALspDiscreteLabelingAlgorithm
      Parameters:
      aLabel - the identifier for which an iterator should be created.
      aCurrentLabelLocations - an ALspLabelLocations object containing locations for the currently placed labels.
      aLabelContext - the label info object.
      aConflictChecker - the conflict checker to be used when evaluating placements.
      aView - the view.
      Returns:
      a new Iterator that iterates over TLspLabelPlacements.

    • createLabelPlacementEvaluator

      protected ILspLabelPlacementEvaluator createLabelPlacementEvaluator(List<TLspLabelID> aLabels, ILspLabelingAlgorithm.LabelContext aLabelContext, ILspLabelConflictChecker aConflictChecker, ILspView aView)
      Description copied from class: ALspDiscreteLabelingAlgorithm
      Creates a new ILspLabelPlacementEvaluator 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 :

      Override this method to provide a custom implementation.

      Specified by:
      createLabelPlacementEvaluator in class ALspDiscreteLabelingAlgorithm
      Parameters:
      aLabels - a list of labels.
      aLabelContext - the label info object.
      aConflictChecker - the conflict checker to be used when evaluating placements.
      aView - the view
      Returns:
      a new ILspLabelPlacementEvaluator.
      See Also: