ilog.views.graphlayout.hierarchical

Class IlvRelativeLevelConstraint

java.lang.Object

ilog.views.graphlayout.hierarchical.IlvHierarchicalConstraint

ilog.views.graphlayout.hierarchical.IlvRelativeConstraint

ilog.views.graphlayout.hierarchical.IlvRelativeLevelConstraint

All Implemented Interfaces:

IlvPersistentObject, Serializable

public class IlvRelativeLevelConstraint
extends IlvRelativeConstraint

The class IlvRelativeLevelConstraint is a constraint to place a node relative to another node. It forces a node to be placed at a level with higher index than another node. The constraint can also be applied to groups of nodes.

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.

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

Among the constraints, this kind is dominated by level range constraints, that is, if the level range for node A is below the level range of node B, then A cannot be forced to be placed in a higher level than B. This kind of constraint is also dominated by the same level constraints, that is, if both nodes A and B are forced to be at the same level, then A cannot be forced to be placed in a higher level than B.

The relative constraints have priorities. Conflicting relative level constraints are resolved by removing the constraint with the smallest priority. Relative level constraints also compete with the links of the graph. Each link acts like a constraint (with the same priority as the link) that forces that the target node is placed in a higher level than the source node.

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.

In recursive layout mode (see IlvHierarchicalLayout.setRecursiveLayoutMode(boolean)), both nodes of the relative level 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 relative level constraint containing nodes of different subgraphs.

Since:

JViews 5.0

See Also:

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

Constructor Summary

Constructors

Constructor and Description
IlvRelativeLevelConstraint(IlvInputStream stream) Creates a new IlvRelativeLevelConstraint from an IlvInputStream.
IlvRelativeLevelConstraint(IlvRelativeLevelConstraint source) Creates a new IlvRelativeLevelConstraint by copying an existing one.
IlvRelativeLevelConstraint(Object lowerNodeOrGroup, Object higherNodeOrGroup, float priority) Creates a new IlvRelativeLevelConstraint .

Method Summary

Modifier and Type	Method and Description
IlvHierarchicalConstraint	copy() Copies the constraint.
Object	getHigherSubject() Returns the subject of this constraint that is placed at the levels with higher index than the other subject.
Object	getLowerSubject() Returns the subject of this constraint that is placed at the levels with lower index than the other subject.
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

IlvRelativeLevelConstraint

public IlvRelativeLevelConstraint(Object lowerNodeOrGroup,
                                  Object higherNodeOrGroup,
                                  float priority)

Creates a new IlvRelativeLevelConstraint . The following example shows how to use the constraint:

 layout.addConstraint(
    new IlvRelativeLevelConstraint(node1, node2, priority)); 
 

This forces node2 to be placed at a level with higher index than node1.

In order to apply the constraint to a groups of nodes, you can use this:

 layout.addConstraint(
     new IlvRelativeLevelConstraint(
         new IlvNodeGroup(nodeVector1),
         new IlvNodeGroup(nodeVector2),
         priority)); 

This forces the nodes of nodeVector2 to be placed at a level with higher index than the nodes of nodeVector1.

Parameters:

lowerNodeOrGroup - A node, or a group of type IlvNodeGroup that is placed in levels below the second node or group.

higherNodeOrGroup - A node, or a group of type IlvNodeGroup that is placed in levels above the first node or group.

priority - The priority of the constraint.

See Also:

IlvHierarchicalLayout.addConstraint(IlvHierarchicalConstraint)

IlvRelativeLevelConstraint

public IlvRelativeLevelConstraint(IlvRelativeLevelConstraint source)

Creates a new IlvRelativeLevelConstraint by copying an existing one.

Parameters:

source - The origin of the copy.

IlvRelativeLevelConstraint

public IlvRelativeLevelConstraint(IlvInputStream stream)
                           throws IOException,
                                  IlvReadFileException

Creates a new IlvRelativeLevelConstraint 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 IlvRelativeConstraint

Parameters:

stream - The output stream.

Throws:

IOException - standard IO error.

getLowerSubject

public final Object getLowerSubject()

Returns the subject of this constraint that is placed at the levels with lower index than the other subject. The subject is either the constraint node, or the instance of IlvNodeGroup that describes a group of nodes.

getHigherSubject

public final Object getHigherSubject()

Returns the subject of this constraint that is placed at the levels with higher index than the other subject. The subject is either the constraint node, or the instance of IlvNodeGroup that describes a group of nodes.