vtkSpanTreeLayoutStrategy Class Reference

#include <vtkSpanTreeLayoutStrategy.h>

Inheritance diagram for vtkSpanTreeLayoutStrategy:

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Collaboration diagram for vtkSpanTreeLayoutStrategy:

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List of all members.

Detailed Description

vtkSpanTreeLayout is a strategy for drawing directed graphs that works by first extracting a spanning tree (more accurately, a spanning forest), and using this both to position graph vertices and to plan the placement of non-tree edges. The latter are drawn with the aid of edge points to produce a tidy drawing.

The approach is best suited to "quasi-trees", graphs where the number of edges is of the same order as the number of nodes; it is less well suited to denser graphs. The boolean flag DepthFirstSpanningTree determines whether a depth-first or breadth-first strategy is used to construct the underlying forest, and the choice of strategy affects the output layout significantly. Informal experiments suggest that the breadth-first strategy is better for denser graphs.

Different layouts could also be produced by plugging in alternative tree layout strategies. To work with the method of routing non-tree edges, any strategy should draw a tree so that levels are equally spaced along the z-axis, precluding for example the use of a radial or balloon layout.

vtkSpanTreeLayout is based on an approach to 3D graph layout first developed as part of the "tulip" tool by Dr. David Auber at LaBRI, U.Bordeaux: see www.tulip-software.org

This implementation departs from the original version in that: (a) it is reconstructed to use Titan/VTK data structures; (b) it uses a faster method for dealing with non-tree edges, requiring at most two edge points per edge (c) allows for plugging in different tree layout methods (d) allows selection of two different strategies for building the underlying layout tree, which can yield significantly different results depending on the data.

Thanks:: Thanks to David Duke from the University of Leeds for providing this implementation.

Examples:: vtkSpanTreeLayoutStrategy (Examples)

Definition at line 69 of file vtkSpanTreeLayoutStrategy.h.


Public Types
typedef vtkGraphLayoutStrategy	Superclass
Public Member Functions
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)
void	Layout ()

virtual void	SetDepthFirstSpanningTree (bool)
virtual bool	GetDepthFirstSpanningTree ()
virtual void	DepthFirstSpanningTreeOn ()
virtual void	DepthFirstSpanningTreeOff ()
Static Public Member Functions
static vtkSpanTreeLayoutStrategy *	New ()
static int	IsTypeOf (const char *type)
static vtkSpanTreeLayoutStrategy *	SafeDownCast (vtkObject *o)
Protected Member Functions
	vtkSpanTreeLayoutStrategy ()
	~vtkSpanTreeLayoutStrategy ()
Protected Attributes
vtkGraphLayoutStrategy *	TreeLayout
bool	DepthFirstSpanningTree

Member Typedef Documentation

typedef vtkGraphLayoutStrategy vtkSpanTreeLayoutStrategy::Superclass

Reimplemented from vtkGraphLayoutStrategy.

Definition at line 74 of file vtkSpanTreeLayoutStrategy.h.

Constructor & Destructor Documentation

vtkSpanTreeLayoutStrategy::vtkSpanTreeLayoutStrategy ( ) [protected]

vtkSpanTreeLayoutStrategy::~vtkSpanTreeLayoutStrategy ( ) [protected]

Member Function Documentation

static vtkSpanTreeLayoutStrategy* vtkSpanTreeLayoutStrategy::New ( ) [static]

Create an object with Debug turned off, modified time initialized to zero, and reference counting on.

Reimplemented from vtkObject.

virtual const char* vtkSpanTreeLayoutStrategy::GetClassName ( ) [virtual]

Reimplemented from vtkGraphLayoutStrategy.

static int vtkSpanTreeLayoutStrategy::IsTypeOf ( const char * name ) [static]

Return 1 if this class type is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkGraphLayoutStrategy.

virtual int vtkSpanTreeLayoutStrategy::IsA ( const char * name ) [virtual]

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkGraphLayoutStrategy.

static vtkSpanTreeLayoutStrategy* vtkSpanTreeLayoutStrategy::SafeDownCast ( vtkObject * o ) [static]

Reimplemented from vtkGraphLayoutStrategy.

void vtkSpanTreeLayoutStrategy::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)			`[virtual]`

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkGraphLayoutStrategy.

virtual void vtkSpanTreeLayoutStrategy::SetDepthFirstSpanningTree ( bool ) [virtual]

If set, base the layout on a depth-first spanning tree, rather than the default breadth-first spanning tree. Switching between DFT and BFT may significantly change the layout, and choice must be made on a per-graph basis. Default value is off.

virtual bool vtkSpanTreeLayoutStrategy::GetDepthFirstSpanningTree ( ) [virtual]

If set, base the layout on a depth-first spanning tree, rather than the default breadth-first spanning tree. Switching between DFT and BFT may significantly change the layout, and choice must be made on a per-graph basis. Default value is off.

virtual void vtkSpanTreeLayoutStrategy::DepthFirstSpanningTreeOn ( ) [virtual]

If set, base the layout on a depth-first spanning tree, rather than the default breadth-first spanning tree. Switching between DFT and BFT may significantly change the layout, and choice must be made on a per-graph basis. Default value is off.

virtual void vtkSpanTreeLayoutStrategy::DepthFirstSpanningTreeOff ( ) [virtual]

If set, base the layout on a depth-first spanning tree, rather than the default breadth-first spanning tree. Switching between DFT and BFT may significantly change the layout, and choice must be made on a per-graph basis. Default value is off.

void vtkSpanTreeLayoutStrategy::Layout ( ) [virtual]

Perform the layout.

Implements vtkGraphLayoutStrategy.