com.tensegrity.graph.layout.edge
Class DefaultEdgeLayout

java.lang.Object
  com.tensegrity.graph.layout.edge.DefaultEdgeLayout

All Implemented Interfaces:

EdgeLayout, Layout

public class DefaultEdgeLayout

extends java.lang.Object

implements EdgeLayout

This EdgeLayout implementation arranges edges without moving any nodes. While most NodeLayout classes are not able to route edges alone but only together with the connected nodes, a layouter which only routes edges is an essential part of every application that supports runtime user-interaction.

This EdgeLayout implementation can be used to completely arrange edges or simply to refine the edges which have already been roughly arranged by a NodeLayout.

This class builds on a set of building blocks. Each building block handles a specific aspect of edge arrangement. The following layout building blocks are provided:

• Path detecting: Routing edges without overlapping nodes.
• Avoid overlaps: Shifting overlapped edge segments to make them recognizable.
• Bridge building: Building bridges at the crossing points between edges for better recognizing of the edge tracks.
• Segment leveling: Shifting of the edge segments on a common level to make relationships clearer and the graph more structured.
• Bend rounding: Rounding of the orthogonal edge bends.
• Label placement: Placement of labels on edges without overlapping nodes and other labels.

The required constants to configure an EdgeLayout instance are defined in class EdgeLayoutConstants.

Version:

$Id: DefaultEdgeLayout.java,v 1.80 2006/06/08 01:30:33 SharokhKhani Exp $

Author:

Sharokh Khani

Constructor Summary

DefaultEdgeLayout()
Constructs an EdgeLayout instance and initializes it with default attributes.

Method Summary

void	afterLayoutHandler() This method will be called after the arrangement of the graph is completed.
void	beforeLayoutHandler() This method will be called before performing layout to allow the layout class to do initialization work.
boolean	error() Returns true if an error has occurred; otherwise false.
AttributeSet	getEdgeAttributesTemplate() Returns the attribute set for edges which is initialized with default values.
java.lang.String	getErrorMessage() Returns the error-message if an error has occurred.
AttributeSet	getLayoutAttributesTemplate() This method return an AttributeSet which contains all properties supported by this Layout.
java.lang.String	getName() Returns the name of the Layout.
AttributeSet	getReport() This method submits a report about the last layout process.
void	init() An instance of this class may be used to arrange different graphs.
boolean	relayout(java.util.ArrayList edgesToReadgust, java.util.ArrayList hindrance, Boundary boundary) Arranges all specified edges, which may be arranged completely or simply readjusted, taking the current edge paths into consideration.
boolean	storePreferEdgePoints(java.util.ArrayList edges) Call this method to store additional edge points.
boolean	storePreferEdgePoints(LayoutableEdge edge, boolean doRemove) Call this method to store additional edge points for a specified edge.
void	updateAttributeSet(AttributeSet layoutAttributs) This method updates a given AttributeSet with the view of consistency.
void	useAttribute(AttributeSet layoutAttributs) This method can be used to configure a layout class.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultEdgeLayout

public DefaultEdgeLayout()

Constructs an EdgeLayout instance and initializes it with default attributes.

Method Detail

updateAttributeSet

public void updateAttributeSet(AttributeSet layoutAttributs)

Description copied from interface: Layout

This method updates a given AttributeSet with the view of consistency.
A tree layout class for example may change the attribute layer distance to radius if the user changes the arrangement type from plan to radial.

Notice: The given AttributeSet must contains valid properties supported by this Layout. Please see Layout.getLayoutAttributesTemplate() for more details.

Specified by:

updateAttributeSet in interface Layout

Parameters:

layoutAttributs - the attributes that are to be updated.

See Also:

Layout.getLayoutAttributesTemplate()

init

public void init()

Description copied from interface: Layout

An instance of this class may be used to arrange different graphs. Since the constructor of this class is called only once, this method must be called to allow a Layout instance to do initialization work before a new graph is assigned.

Specified by:

init in interface Layout

getName

public java.lang.String getName()

Description copied from interface: Layout

Returns the name of the Layout. This name will be used to identify a layout and must be unique.

Specified by:

getName in interface Layout

Returns:

String The name of this layout class.

useAttribute

public void useAttribute(AttributeSet layoutAttributs)

Description copied from interface: Layout

This method can be used to configure a layout class. The method Layout#getLayoutAttributesTemplate() can be used to obtained a copy of default AttributeSet that contains all properties supported by this Layout.

Specified by:

useAttribute in interface Layout

Parameters:

layoutAttributs - The attributes that are to be used in the next layout process.

beforeLayoutHandler

public void beforeLayoutHandler()

Description copied from interface: Layout

This method will be called before performing layout to allow the layout class to do initialization work.

Specified by:

beforeLayoutHandler in interface Layout

storePreferEdgePoints

public boolean storePreferEdgePoints(java.util.ArrayList edges)

Description copied from interface: EdgeLayout

Call this method to store additional edge points. An EdgeLayout should take the current edge paths into consideration because in most cases the edge paths will have already been arranged by a NodeLayout.

Specified by:

storePreferEdgePoints in interface EdgeLayout

Parameters:

edges - a List containing the edges of which the additional points are to be stored.

Returns:

true if the layout was successful; otherwise false.

storePreferEdgePoints

public boolean storePreferEdgePoints(LayoutableEdge edge,
                                     boolean doRemove)

Description copied from interface: EdgeLayout

Call this method to store additional edge points for a specified edge. An EdgeLayout should take the current edge paths into consideration because in most cases the edge paths will have already been arranged by a NodeLayout.

Specified by:

storePreferEdgePoints in interface EdgeLayout

Parameters:

edge - the edges of which the additional points are to be stored.

doRemove - specifies whether the existing points should be overwritten or not

Returns:

true if the layout was successful; otherwise false.

relayout

public boolean relayout(java.util.ArrayList edgesToReadgust,
                        java.util.ArrayList hindrance,
                        Boundary boundary)

Description copied from interface: EdgeLayout

Arranges all specified edges, which may be arranged completely or simply readjusted, taking the current edge paths into consideration.

Specified by:

relayout in interface EdgeLayout

Parameters:

edgesToReadgust - All edges that should be rearranged. The elements the ArrayList are from type EdgeMap.

hindrance - A list of hindrances. Each hindrance is an integer array of length 5 containing a node boundary and its identifier, as shown here:

• left position of the node.
• top position of the node.
• right position of the node.
• bottom position of the node.
• the identifier of the node.

boundary - the total available area that can be used by the edge layout

Returns:

true if the layout was successful; otherwise false.

afterLayoutHandler

public void afterLayoutHandler()

Description copied from interface: Layout

This method will be called after the arrangement of the graph is completed. It allows the layout class to do post-initialization work.

Specified by:

afterLayoutHandler in interface Layout

getLayoutAttributesTemplate

public AttributeSet getLayoutAttributesTemplate()

Description copied from interface: Layout

This method return an AttributeSet which contains all properties supported by this Layout. The provided AttributeSet can be modified to configure this Layout.The method Layout.useAttribute(AttributeSet) will be used to put a modified copy of this AttributeSet.

Specified by:

getLayoutAttributesTemplate in interface Layout

Returns:

Returns a the default AttributeSet of this Layout if any; otherwise null.

getEdgeAttributesTemplate

public AttributeSet getEdgeAttributesTemplate()

Description copied from interface: EdgeLayout

Returns the attribute set for edges which is initialized with default values.
Notice: The default edge attributes are not to be confused with layout attributes. The layout attributes configure the layout as a whole. But some layout classes also allow the configuration of edges for alternate treatment.

Specified by:

getEdgeAttributesTemplate in interface EdgeLayout

Returns:

Returns a the default AttributeSet for nodes if any; otherwise null.

error

public boolean error()

Description copied from interface: Layout

Returns true if an error has occurred; otherwise false. You can use Layout.getErrorMessage() to obtain a description text about the last occurred error.

Specified by:

error in interface Layout

Returns:

Returns true if an error has occurred; otherwise false.

getErrorMessage

public java.lang.String getErrorMessage()

Description copied from interface: Layout

Returns the error-message if an error has occurred. You can use Layout.error() to find out whether an error has occurred.

Specified by:

getErrorMessage in interface Layout

Returns:

Returns the error description

getReport

public AttributeSet getReport()

Description copied from interface: Layout

This method submits a report about the last layout process. It provides detail information accordingly.A report contains typically the calculation durations of different processing steps.

Specified by:

getReport in interface Layout

Returns:

Returns an AttributeSet which contains the report.