The level index is a special case of a level range constraint
(see Level range constraints (HL)). It forces
the node to one particular level. For your convenience, you can
specify the level index of a node directly by the method:
void setSpecNodeLevelIndex(Object node, int index)
You pass a single node as the first argument (not a node group).
The default index value is
-1
. If the default value is used, or if a node is set to a negative
level index, the level index is considered to be unspecified. In
this case the layout algorithm automatically calculates an
appropriate level index during the leveling phase of the algorithm.
To obtain the specified level index for a
node, use the method:
int getSpecNodeLevelIndex(Object node)
However, this method returns the value that was set by
setSpecNodeLevelIndex
. If the level index was specified by allocating a corresponding
level range constraint that has the same meaning,
getSpecNodeLevelIndex
still returns
-1
.
Warning
Using arbitrarily large level indexes is not recommended. For
instance, if you set the level index of a node to
100000
, the layout algorithm creates 100,000 levels even if the graph
has far fewer nodes. It causes the layout algorithm to become
slow.