ilog.views.graphlayout.hierarchical

Class IlvGroupSpreadConstraint

java.lang.Object

ilog.views.graphlayout.hierarchical.IlvHierarchicalConstraint

ilog.views.graphlayout.hierarchical.IlvGroupSpreadConstraint

All Implemented Interfaces:

IlvPersistentObject

public class IlvGroupSpreadConstraint
extends IlvHierarchicalConstraint

The class IlvGroupSpreadConstraint is a constraint that forces a group of nodes to be placed no more than a specified number of levels apart.

Nodes are organized in horizontal or vertical levels numbered from 0 to "n". If the link flow direction is from top to bottom, the nodes with level index 0 are placed in the topmost level, and the nodes with higher level indexes are placed in the levels below. If the link flow direction is from left to right, the nodes with level index 0 are placed in the leftmost level, and the nodes with higher level indexes are placed in the levels farther to the right.

For instance, a constraint with spread size 2 forces the group to be placed such that the group node with smallest level index is no more than 2 levels apart from the group node with largest level index. All remaining nodes are placed in between. Assume that the group consists of the nodes A, B, and C. The group spread constraint is satisfied if the levels of A, B and C are 1, 2, 3. It is also satisfied if the levels of A, B and C are 10, 9, 8, or 10, 10, 12 or 10, 11, 11, or 10, 10, 10. But it is not satisfied if the levels of A, B and C are 10, 13, 12, because the highest node B is in this case more than 2 levels apart from the lowest node A.

The constraint is evaluated, if the incremental mode is disabled. If the incremental mode is enabled, the constraint is only evaluated if the nodes of the group are marked for incremental recalculation, because otherwise, the incremental positions of the nodes are dominant.

Among the constraints, this kind has the highest priority. If several conflicting constraints are specified (such as two nodes must be placed no more than 2 number of levels apart, but in level 1 and 10), the constraints with lower priority are ignored during layout.

The automatic conflict resolution can handle conflicting constraints. However, to speedup the layout, it is recommended to specify constraints in a way such that there are no conflicts.

The group spread constraint has the same priority as the same level constraint, because both cannot be conflicting. In fact, there are two ways of forcing two nodes to the same level: use the same level constraint, or use a group spread constraint of a group of two nodes with spread size 0.

In recursive layout mode (see IlvHierarchicalLayout.setRecursiveLayoutMode(boolean)), all nodes of a group spread constraint must belong to the same subgraph, and the constraint must be installed at the layout instance that is attached to this subgraph. It is not possible to have a group spread constraint containing nodes of different subgraphs.

Since:

JViews 5.0

See Also:

IlvHierarchicalLayout.addConstraint(IlvHierarchicalConstraint), IlvHierarchicalLayout.setIncrementalMode(boolean), IlvHierarchicalLayout.markForIncremental(Object)

Constructor Summary

Constructors

Constructor and Description
IlvGroupSpreadConstraint(IlvGroupSpreadConstraint source) Creates a new IlvGroupSpreadConstraint by copying an existing one.
IlvGroupSpreadConstraint(IlvInputStream stream) Creates a new IlvGroupSpreadConstraint from an IlvInputStream.
IlvGroupSpreadConstraint(IlvNodeGroup groupArg, int sizeArg) Creates a new IlvGroupSpreadConstraint .

Method Summary

Modifier and Type	Method and Description
IlvHierarchicalConstraint	copy() Copies the constraint.
IlvNodeGroup	getGroup() Returns the group of this constraint.
int	getSpreadSize() Returns the spread size of this constraint.
void	setSpreadSize(int spreadSize) Sets the spread size of the group.
void	write(IlvOutputStream stream) Writes the constraint to the output stream.

Methods inherited from class ilog.views.graphlayout.hierarchical.IlvHierarchicalConstraint

getPriority, setPriority

Methods inherited from class java.lang.Object

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

Constructor Detail

IlvGroupSpreadConstraint

public IlvGroupSpreadConstraint(IlvNodeGroup groupArg,
                                int sizeArg)

Creates a new IlvGroupSpreadConstraint .

The following examples show how to use the constraint:

 layout.addConstraint(
     new IlvGroupSpreadConstraint(new IlvNodeGroup(nodeVector), 2));

This forces the nodes of nodeVector to be placed no more than 2 levels apart.

Parameters:

groupArg - The node group.

sizeArg - The maximum number of levels two nodes of the group can be apart.

See Also:

setSpreadSize(int), IlvHierarchicalLayout.addConstraint(IlvHierarchicalConstraint)

IlvGroupSpreadConstraint

public IlvGroupSpreadConstraint(IlvGroupSpreadConstraint source)

Creates a new IlvGroupSpreadConstraint by copying an existing one.

Parameters:

source - The origin of the copy.

IlvGroupSpreadConstraint

public IlvGroupSpreadConstraint(IlvInputStream stream)
                         throws IOException,
                                IlvReadFileException

Creates a new IlvGroupSpreadConstraint from an IlvInputStream.

Parameters:

stream - The input stream from which the property must be read.

Throws:

IlvReadFileException - if an error occurs while reading.

IOException

Method Detail

copy

public IlvHierarchicalConstraint copy()

Copies the constraint.

Specified by:

copy in class IlvHierarchicalConstraint

write

public void write(IlvOutputStream stream)
           throws IOException

Writes the constraint to the output stream.

Specified by:

write in interface IlvPersistentObject

Overrides:

write in class IlvHierarchicalConstraint

Parameters:

stream - The output stream.

Throws:

IOException - standard IO error.

getGroup

public final IlvNodeGroup getGroup()

Returns the group of this constraint.

getSpreadSize

public final int getSpreadSize()

Returns the spread size of this constraint.

See Also:

setSpreadSize(int)

setSpreadSize

public final void setSpreadSize(int spreadSize)

Sets the spread size of the group.

Parameters:

spreadSize - The maximum number of levels two nodes of the group can be apart.

See Also:

getSpreadSize()