C

DoubleLayerSubtreePlacer

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The DoubleLayerSubtreePlacer arranges the subtrees of a local root alternating in two layers.

Remarks

Layout Style

This ISubtreePlacer arranges nodes from top to bottom. It places the subtrees in two horizontal layers below the root. They are distributed in an alternating fashion, i.e., adjacent subtrees are in different layers.

This subtree placer is especially useful for leaves with a large width.

Default Values of Properties

NameDefaultDescription
layerSpacingRatio0.33
The distance between the two layers of subtrees is a third of the distance between the root and the upper layer.
rootAlignmentSubtreeRootAlignment.TRAILING
spacing20

See Also

Developer's Guide

Members

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Constructors

DoubleLayerSubtreePlacer

()
Creates a new instance of this class.

Parameters

Properties

alignPorts

: boolean
Gets or sets whether nodes are placed so that the source and target port of an edge are aligned.

Dependent on the SubtreeRootAlignment type the subtree root is moved in a way that the edge connecting the root to one of its children is straightened.

This setting only applies to the following SubtreeRootAlignments:

final

Property Value

true if the ports are to be aligned, false otherwise

Default Value

The default value is: false
Ports are not aligned.

Sample Graphs

ShownSetting: false

layerSpacingRatio

: number
Gets or sets the ratio of the spacing between the root and the children in the upper layer and the spacing between the two layers of subtrees.
Negative ratios will lead to node overlaps.
final

Property Value

the ratio to determine the spacing between the two layers of subtrees

Default Value

The default value is: 0.33
The distance between the two layers of subtrees is a third of the distance between the root and the upper layer.

Sample Graphs

ShownSetting: 0.33

rootAlignment

: SubtreeRootAlignment
Gets or sets the SubtreeRootAlignment that defines how the root node is aligned with its children and their shapes.
conversionfinal

Property Value

the SubtreeRootAlignment value specifying the location relative to the subtrees

Throws

Exception ({ name: 'ArgumentError' })
if the given root alignment is null

Default Value

The default value is: SubtreeRootAlignment.TRAILING

spacing

: number
Gets or sets the spacing between subtrees.
The spacing needs to be non-negative.
final

Property Value

the distance between subtrees

Throws

Exception ({ name: 'ArgumentError' })
if the given spacing is negative

Default Value

The default value is: 20

Sample Graphs

ShownSetting: Spacing 20 using SingleLayerSubtreePlacer

transformation

: SubtreeTransform
Gets the modification matrix that defines the direction of the subtree.
conversionfinal

Property Value

the modification matrix

Default Value

The default value is: SubtreeTransform.NONE

Methods

createFromSketchComparator

(): function(LayoutEdge, LayoutEdge): number
Creates an edge comparison which takes the initial coordinates of the nodes into account.
This comparison defines the order of the outgoing edges of a node before the actual placement of the node's subtree is calculated.
final

Return Value

function(LayoutEdge, LayoutEdge): number
the comparison for the edges

createProcessor

(
treeLayout: TreeLayout
graph: LayoutGraph
currentRoot: LayoutNode
): ISubtreePlacerProcessor
Creates an optional ISubtreePlacerProcessor for pre- and post-processing.
This method is called by TreeLayout before arranging the SubtreeShapes. If no pre- or post-processing is needed, this method may return null.
final

Parameters

treeLayout: TreeLayout
the current TreeLayout instance
graph: LayoutGraph
the input graph
currentRoot: LayoutNode
the root node handled by this ISubtreePlacer

Return Value

ISubtreePlacerProcessor
a ISubtreePlacerProcessor instance or null

determineChildConnectors

(localRoot: LayoutNode, connectorMap: IMapper<LayoutNode, ParentConnectorDirection>)
Provides the direction of the connector to the SubtreeShape for each child node.
This method is called by TreeLayout before the SubtreeShapes for the children of the local root node are calculated. The direction specifiers are stored in the given map for all child nodes of the local root.
final

Parameters

localRoot: LayoutNode
the local root node
connectorMap: IMapper<LayoutNode, ParentConnectorDirection>
the IMapper<K, V> that is used for storing the direction specifiers of the child nodes

placeSubtree

(
nodeShapeProvider: IMapper<LayoutNode, SubtreeShape>
subtreeShapeProvider: IMapper<LayoutNode, SubtreeShape>
graph: LayoutGraph
localRoot: LayoutNode
parentConnectorDirection: ParentConnectorDirection
): SubtreeShape
Arranges the SubtreeShapes of the local root and its children and routes the edges that connect them.

This method is the main method of the tree layout algorithm. It is called by TreeLayout in each recursion step to place the local root in relation to its children. Their shapes will be merged into one SubtreeShape, which is returned by this method.

The SubtreeShape for the local root can be obtained from the nodeShapeProvider. subtreeShapeProvider contains the SubtreeShapes assigned to the child nodes.

Due to the order in which the tree nodes are processed, it is guaranteed that at the time of the invocation of this method the SubtreeShape of every descendant node has already been calculated.

final

Parameters

nodeShapeProvider: IMapper<LayoutNode, SubtreeShape>
the IMapper<K, V> for obtaining an initial shape of the root node
subtreeShapeProvider: IMapper<LayoutNode, SubtreeShape>
the IMapper<K, V> for accessing the pre-calculated shapes of the subtrees
graph: LayoutGraph
the input graph
localRoot: LayoutNode
the root of the subtree that should be arranged by this method
parentConnectorDirection: ParentConnectorDirection
the direction specifier for the connector of the local root node to its parent node

Return Value

SubtreeShape
the combined shape of the whole subtree