y.layout.hierarchic.incremental
Class DefaultLayerSequencer

java.lang.Object
  y.layout.hierarchic.incremental.DefaultLayerSequencer

All Implemented Interfaces:

Sequencer

public class DefaultLayerSequencer
extends Object
implements Sequencer

This class implements the second phase of the Sugiyama algorithm. It minimizes the crossings in the diagram by using either the barycentric or median heuristic.

Field Summary

static byte	BARYCENTER_HEURISTIC Weight assignment heuristic specifier.
static byte	MEDIAN_HEURISTIC Weight assignment heuristic specifier.

Constructor Summary

DefaultLayerSequencer()

Method Summary

long	getMaximalDuration() Returns the proposed maximal duration for the calculation of the sequence.
int	getRandomizationRounds() Returns the number of randomized rounds this algorithm will try if there was no optimal solution.
byte	getWeightHeuristic() Returns the currently set weight heuristic.
boolean	isGroupTranspositionEnabled() Returns whether or not the group transposition heuristic should be used.
boolean	isTranspositionEnabled() Returns whether or not the transposition crossing minimization heuristic should be used.
void	sequenceNodeLayers(LayoutGraph graph, Layers glayers, LayoutDataProvider ldp, ItemFactory itemFactory) Called by HierarchicLayouter during the second phase.
void	setGroupTranspositionEnabled(boolean b) Specifies whether or not an additional crossing minimization heuristic should be used in the presence of grouped graphs.
void	setMaximalDuration(long msec) Sets the maximum amount of time granted for this sequencer per execution.
void	setRandomizationRounds(int randomizationRounds) Sets the number of additional rounds the algorithm will restart with randomized solutions as long as there might be a better solution to the current best.
void	setTranspositionEnabled(boolean b) Specifies whether or not an additional crossing minimization heuristic should be used.
void	setWeightHeuristic(byte h) Sets the weight heuristic to be used.

Methods inherited from class java.lang.Object

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

Field Detail

BARYCENTER_HEURISTIC

public static final byte BARYCENTER_HEURISTIC

Weight assignment heuristic specifier. A node position within a layer will be determined by the barycenter of its successor (downward pass) and predecessor (upward pass) nodes.

See Also:

Constant Field Values

MEDIAN_HEURISTIC

public static final byte MEDIAN_HEURISTIC

Weight assignment heuristic specifier. A node position within a layer will be determined by the median position of its successor (downward pass) and predecessor (upward pass) nodes.

See Also:

Constant Field Values

Constructor Detail

DefaultLayerSequencer

public DefaultLayerSequencer()

Method Detail

setTranspositionEnabled

public void setTranspositionEnabled(boolean b)

Specifies whether or not an additional crossing minimization heuristic should be used. Activating this heuristic can reduce the overall number of edge crossings. On the other hand its activation increases running time.

By default the transposition rule is active.

Parameters:

b - whether to use the heuristic

isTranspositionEnabled

public boolean isTranspositionEnabled()

Returns whether or not the transposition crossing minimization heuristic should be used.

Returns:

whether the heuristic is active

See Also:

setTranspositionEnabled(boolean)

setGroupTranspositionEnabled

public void setGroupTranspositionEnabled(boolean b)

Specifies whether or not an additional crossing minimization heuristic should be used in the presence of grouped graphs. Activating this heuristic can reduce the overall number of edge crossings in grouped graphs. On the other hand its activation increases running time.

By default the transposition rule is not active.

Parameters:

b - whether to use the heuristic

isGroupTranspositionEnabled

public boolean isGroupTranspositionEnabled()

Returns whether or not the group transposition heuristic should be used.

Returns:

whether the heuristic is active

See Also:

setGroupTranspositionEnabled(boolean)

setWeightHeuristic

public void setWeightHeuristic(byte h)

Sets the weight heuristic to be used. By default BARYCENTER_HEURISTIC is set.

Throws:

IllegalArgumentException - if the constant is unknown

Parameters:

h - one of BARYCENTER_HEURISTIC and MEDIAN_HEURISTIC.

getWeightHeuristic

public byte getWeightHeuristic()

Returns the currently set weight heuristic.

Returns:

a byte constant as defined in this class

See Also:

setWeightHeuristic(byte)

getMaximalDuration

public long getMaximalDuration()

Returns the proposed maximal duration for the calculation of the sequence. The default is 10000

Returns:

the time allowed for retrying in milliseconds

getRandomizationRounds

public int getRandomizationRounds()

Returns the number of randomized rounds this algorithm will try if there was no optimal solution.

Returns:

the number of rounds. Default is 50.

setRandomizationRounds

public void setRandomizationRounds(int randomizationRounds)

Sets the number of additional rounds the algorithm will restart with randomized solutions as long as there might be a better solution to the current best.

Parameters:

randomizationRounds - the new number of additional rounds

setMaximalDuration

public void setMaximalDuration(long msec)

Sets the maximum amount of time granted for this sequencer per execution.

Parameters:

msec - granted time in milliseconds

sequenceNodeLayers

public void sequenceNodeLayers(LayoutGraph graph,
                               Layers glayers,
                               LayoutDataProvider ldp,
                               ItemFactory itemFactory)

Description copied from interface: Sequencer

Called by HierarchicLayouter during the second phase. Calculates a sequence of the nodes in layers and finally writes back the calculated sequence using the Layer.setNodeOrder(y.base.YList) method.

Specified by:

sequenceNodeLayers in interface Sequencer

Parameters:

graph - the graph that contains the elements from layers

glayers - the Layer implementation that holds the Layers for sequencing

ldp - the LayoutDataProvider that provides the necessary NodeData and EdgeData

itemFactory - an ItemFactory implementation that can be used to modify the graph consistently