ilog.views.graphlayout.springembedder

Class IlvSpringEmbedderLayout

java.lang.Object

ilog.views.graphlayout.IlvGraphLayout

ilog.views.graphlayout.springembedder.IlvSpringEmbedderLayout

Deprecated.

Beginning with JViews 8.5, use the class IlvUniformLengthEdgesLayout instead.

public class IlvSpringEmbedderLayout
extends IlvGraphLayout

The main class for the Spring Embedder Layout algorithm.

The Spring Embedder Layout algorithm can be used to lay out any type of graph. It often provides a drawing with no edge crossings or few edge crossings for small- and medium-sized graphs. The nodes are placed inside a rectangle which is controlled by the layoutRegion parameter. It is important to specify a layout region that is in proportion to the number and size of the nodes.

This algorithm is based on an analogy between graph drawings and mechanical systems: Nodes correspond to point masses and edges correspond to springs. Attractive and repulsive forces between each pair of nodes are defined depending on the distance between the nodes and the connectivity of the graph. The algorithm searches a sort of minimal-energy configuration of the graph, computing iteratively the positions of the nodes.

Sample drawings produced with the Spring Embedder algorithm:

See the corresponding chapter of the User's Manual for details on the algorithm, the types of graphs for which this algorithm can be used, the features and limitations, code samples, parameters, and so on.

Note that the initial position of the nodes (at the moment you start the layout) does not affect the resulting layout However, nodes specified as fixed are not moved if you call the method setPreserveFixedNodes with a true argument.

CSS example:

SDM {
GraphLayout : true;
}

GraphLayout {
graphLayout : @#layout;
// optional settings for the graph layout renderer
}

Subobject#layout {
class : "ilog.views.graphlayout.springembedder.IlvSpringEmbedderLayout";
allowedTime : "3";
animate : "false";
coordinatesMode : "MANAGER_COORDINATES";
layoutOfConnectedComponentsEnabled : "false";
linkStyle : "STRAIGHT_LINE_STYLE";
memorySavings : "false";
minBusyTime : "3";
seedValueForRandomGenerator : "3";
springConstant : "3.0";
useSeedValueForRandomGenerator : "false";
}

CSS specification of per-node and per-link layout parameters:

The following table lists the per-object rendering properties of the GraphLayout renderer:

Property	Type	Default	Description
GraphLayout	IlvGraphLayout	null	Lets you define a different graph layout algorithm for each subgraph. If one is not specified, the same algorithm is applied recursively to all subgraphs.
LayoutFixed	String	false	Deprecated, replaced by Fixed.
Fixed	String	false	Lets you specify that the node or link must not be moved or reshaped by the layout algorithm.
LayoutGroup	String	null	Lets you apply the algorithm to different groups of objects, one group after the other.
LayoutIgnored	boolean	false	If true, the object is ignored by the layout.

The per-node and per-link layout parameters are specified in the style sheet through the CSS rules for nodes and links, not through the CSS rule for graph layout. For instance:

link.tag {
LinkStyle : "ORTHOGONAL_STYLE";
}

Note that the names of the node and link layout parameters use an initial capital, unlike the regular properties. See also the documentation of the class IlvGraphLayoutRenderer.

See Also:

IlvUniformLengthEdgesLayout

Property Summary

Properties

Modifier and Type	Property and Description
long	allowedTime Deprecated. Sets the upper limit for the duration of the layout algorithm.
boolean	animate Deprecated. If the argument is true, specifies that layout algorithms that support the animation mechanism will require the graph model to redraw the graph after each iteration or step.
java.lang.String	class Deprecated. Default constructor.
int	coordinatesMode Deprecated. Sets the coordinates mode to be used during layout.
boolean	layoutOfConnectedComponentsEnabled Deprecated. Sets whether the generic connected component layout mechanism is enabled.
int	linkStyle Deprecated. Sets the style of the shape of the links.
boolean	memorySavings Deprecated. Sets whether the layout algorithm uses the memory saving mode.
long	minBusyTime Deprecated. Sets the minimal time that the layout algorithm can be busy.
long	seedValueForRandomGenerator Deprecated. Sets the seed value for the random generator.
double	springConstant Deprecated. Sets the constant for the springs.
boolean	useSeedValueForRandomGenerator Deprecated. Sets whether the user-defined seed value should be used for the random generator.

Method Summary

Methods inherited from class java.lang.Object

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

Property Detail

class

public java.lang.String class

Deprecated.

Default constructor.

CSS example: class : "ilog.views.graphlayout.springembedder.IlvSpringEmbedderLayout";

allowedTime

public long allowedTime

Deprecated.

Sets the upper limit for the duration of the layout algorithm.

When an iterative layout algorithm is used, the iterations can be stopped when this time is exceeded. Noniterative algorithms can also use this parameter as an upper limit for the computation time. The default value is normally 32000 (32 seconds). Subclasses that support this feature can use a different default value depending on their particular behavior. Layout algorithms that are stopped in this way set the result code of the layout report either to IlvGraphLayoutReport#STOPPED_AND_VALID or to IlvGraphLayoutReport#STOPPED_AND_INVALID.

When the connected components of disconnected graphs are laid out separately (see #supportsLayoutOfConnectedComponents()), the specified allowed time is considered as the total time for the layout of all the connected components plus the time for the connected components layout.

Note that the layout algorithm may not obey exactly the allowed time specification.

Note for implementers of layout algorithms: the method #performLayout(boolean, boolean, boolean) does NOT automatically stop the layout when the allowed time is exceeded. It is the sole responsibility of the implementation of the method #layout(boolean) to do this.

A RuntimeException is thrown if the layout does not support this mechanism.

CSS example: allowedTime : "3";

animate

public boolean animate

Deprecated.

If the argument is true, specifies that layout algorithms that support the animation mechanism will require the graph model to redraw the graph after each iteration or step.

The default value is false.

A RuntimeException is thrown if the layout does not support this option.

Note that to obtain a redraw of an IlvGrapher after each iteration or step, the method #performLayout(boolean, boolean, boolean) must be called with the value true for the redraw argument.

CSS example: animate : "false";

coordinatesMode

public int coordinatesMode

Deprecated.

Sets the coordinates mode to be used during layout.

Valid values are:

• ilog.views.graphlayout.IlvGraphLayout#MANAGER_COORDINATES - The geometry of the graph is computed using the coordinate space of the manager (that is, the attached IlvGrapher) without applying any transformation.

  This mode should be used if you visualize the graph at zoom level 1, or you do not visualize it at all, or the graph contains only fully zoomable objects. In all these cases there is no need to take the transformer into account during the layout.

  Note that in this mode the dimensional parameters of the layout algorithms are considered as being specified in manager coordinates.

• ilog.views.graphlayout.IlvGraphLayout#VIEW_COORDINATES - The geometry of the graph is computed in the coordinate space of the manager view. More exactly, all the coordinates are transformed using the current reference transformer.

  This mode should be used if you want the dimensional parameters of the layout algorithms to be considered as being specified in manager view coordinates.

• ilog.views.graphlayout.IlvGraphLayout#INVERSE_VIEW_COORDINATES - The geometry of the graph is computed using the coordinate space of the manager view and then applying the inverse transformation. This mode is equivalent to the "manager coordinates" mode if the geometry of the graphic objects strictly obeys the transformer. (A small difference may exist because of the limited precision of the computations.)

  On the contrary, if some graphic objects are either nonzoomable (see IlvGraphic#zoomable) or semizoomable (for example, links with a maximum line width), this mode gives different results than the manager coordinates mode. These results are optimal if the graph is visualized using the same transformer as the one taken into account during the layout.

  Note that in this mode the dimensional parameters of the layout algorithms are considered as being specified in manager coordinates.

The default value is IlvGraphLayout#INVERSE_VIEW_COORDINATES.

This option is useful only if the attached graph model is an IlvGrapherAdapter (or a subclass). Otherwise, it has no effect. Note: the coordinates mode of the layout is used only while this layout is running. If layout is not running, operations on the grapher adapter use the coordinates mode that was set on the grapher adapter directly (see IlvGrapherAdapter#setCoordinatesMode).

CSS example: coordinatesMode : "MANAGER_COORDINATES";

Allowed values:

MANAGER_COORDINATES

VIEW_COORDINATES

INVERSE_VIEW_COORDINATES

layoutOfConnectedComponentsEnabled

public boolean layoutOfConnectedComponentsEnabled

Deprecated.

Sets whether the generic connected component layout mechanism is enabled. If enabled on a layout class that supports this mechanism (see #supportsLayoutOfConnectedComponents()), the method #performLayout(boolean, boolean, boolean) cuts the attached graph model into connected components and lays out each connected component separately. Then the connected components are placed using the layout instance returned by the method #getLayoutOfConnectedComponents().

Notice that the connected component layout is not used if the graph is connected.

A RuntimeException is thrown if the layout does not support this mechanism.

The default value is the value returned by the method #isLayoutOfConnectedComponentsEnabledByDefault().

CSS example: layoutOfConnectedComponentsEnabled : "false";

linkStyle

public int linkStyle

Deprecated.

Sets the style of the shape of the links. Valid values are STRAIGHT_LINE_STYLE (the links are given a straight-line shape) and NO_RESHAPE_STYLE (no reshape is performed on the links).

This feature can be useful if the graph contains links that have intermediate points and are not straight-line links, for instance IlvPolylineLinkImage links with intermediate points.

Note that when the graph attached to the layout is of type IlvGrapher, the effect of the link reshaping depends on the type of the links and the connectors installed at the node. For all link styles, we recommend using links of type IlvPolylineLinkImage and either no link connector or any link connector except IlvFreeLinkConnector. Other link or connector types may cause an IlvInappropriateLinkException during layout. You can use the method IlvGraphLayoutUtil#EnsureAppropriateLinks before layout or when the exception is caught to convert all links and link connectors to an appropriate type.

The default value is STRAIGHT_LINE_STYLE.

CSS example: linkStyle : "STRAIGHT_LINE_STYLE";

Allowed values:
STRAIGHT_LINE_STYLE		Straight-line links
NO_RESHAPE_STYLE		No link reshape

memorySavings

public boolean memorySavings

Deprecated.

Sets whether the layout algorithm uses the memory saving mode. If the argument is true, indicates that the layout algorithm is to use the implementation that consumes less memory.

The default value of the parameter is false.

This option should not have any effect on the resulting layout. However, the implementation of the method #layout is solely responsible for the resulting layout.

A RuntimeException is thrown if the layout does not support this option.

CSS example: memorySavings : "false";

minBusyTime

public long minBusyTime

Deprecated.

Sets the minimal time that the layout algorithm can be busy. This is the time between two calls of #layoutStepPerformed() when the method #callLayoutStepPerformedIfNeeded() is used.

The objective is to avoid the overhead of #layoutStepPerformed() becoming too high if the method is called too often. Internal routines of layout algorithms usually call #callLayoutStepPerformedIfNeeded(), which calls #layoutStepPerformed() if the time since the last call was at least the minimal busy time.

The default value is 50 (milliseconds).

CSS example: minBusyTime : "3";

seedValueForRandomGenerator

public long seedValueForRandomGenerator

Deprecated.

Sets the seed value for the random generator. The default value is 0. The user-defined seed value is used only if you call setUseSeedValueForRandomGenerator(boolean) with a true argument.

A RuntimeException is thrown if the layout does not support this mechanism.

CSS example: seedValueForRandomGenerator : "3";

See Also:

useSeedValueForRandomGenerator

springConstant

public double springConstant

Deprecated.

Sets the constant for the springs. The constant must be positive; if negative, the value is not changed. Recommended values range from 6. to 18.. A better range is from 12. to 16..

CSS example: springConstant : "3.0";

useSeedValueForRandomGenerator

public boolean useSeedValueForRandomGenerator

Deprecated.

Sets whether the user-defined seed value should be used for the random generator.

A RuntimeException is thrown if the layout does not support this mechanism.

CSS example: useSeedValueForRandomGenerator : "false";

See Also:

seedValueForRandomGenerator