Implementation of the Planar-Straight layout algorithm. More...

#include <ogdf/planarlayout/PlanarStraightLayout.h>

Inheritance diagram for ogdf::PlanarStraightLayout:

Public Member Functions
	PlanarStraightLayout ()
	Constructs an instance of the Planar-Straight layout algorithm.

	~PlanarStraightLayout ()

Optional parameters
bool	sizeOptimization () const
	Returns the current setting of option sizeOptimization.

void	sizeOptimization (bool opt)
	Sets the option sizeOptimization to `opt`.

double	baseRatio () const
	Returns the current setting of option baseRatio.

void	baseRatio (double ratio)
	Sets the option baseRatio to `ratio`.

Module options
void	setAugmenter (AugmentationModule *pAugmenter)
	Sets the augmentation module.

void	setShellingOrder (ShellingOrderModule *pOrder)
	Sets the shelling order module.

void	setEmbedder (EmbedderModule *pEmbedder)
	Sets the module option for the graph embedding algorithm.

Public Member Functions inherited from ogdf::PlanarGridLayoutModule
	PlanarGridLayoutModule ()
	Initializes a planar grid layout module.

virtual	~PlanarGridLayoutModule ()

void	callFixEmbed (GraphAttributes &AG, adjEntry adjExternal=nullptr)
	Calls the grid layout algorithm with a fixed planar embedding (general call).

void	callGridFixEmbed (const Graph &G, GridLayout &gridLayout, adjEntry adjExternal=nullptr)
	Calls the grid layout algorithm with a fixed planar embedding (call for GridLayout).

Public Member Functions inherited from ogdf::GridLayoutModule
	GridLayoutModule ()
	Initializes a grid layout module.

virtual	~GridLayoutModule ()

virtual void	call (GraphAttributes &GA) override final
	Calls the grid layout algorithm (general call).

void	callGrid (const Graph &G, GridLayout &gridLayout)
	Calls the grid layout algorithm (call for GridLayout).

const IPoint &	gridBoundingBox () const

double	separation () const
	Returns the current setting of the minimum distance between nodes.

void	separation (double sep)
	Sets the minimum distance between nodes.

Public Member Functions inherited from ogdf::LayoutModule
	LayoutModule ()
	Initializes a layout module.

virtual	~LayoutModule ()

void	operator() (GraphAttributes &GA)
	Computes a layout of graph `GA`.

Private Member Functions
void	computeCoordinates (const Graph &G, ShellingOrder &lmc, NodeArray< int > &x, NodeArray< int > &y)

virtual void	doCall (const Graph &G, adjEntry adjExternal, GridLayout &gridLayout, IPoint &boundingBox, bool fixEmbedding) override
	Implements the algorithm call.

Private Attributes
std::unique_ptr< AugmentationModule >	m_augmenter
	The augmentation module.

double	m_baseRatio
	The option for specifying the base ratio.

std::unique_ptr< ShellingOrderModule >	m_computeOrder
	The shelling order module.

std::unique_ptr< EmbedderModule >	m_embedder
	The planar embedder module.

bool	m_sizeOptimization
	The option for size optimization.

Additional Inherited Members
Protected Member Functions inherited from ogdf::PlanarGridLayoutModule
virtual void	doCall (const Graph &G, GridLayout &gridLayout, IPoint &boundingBox) override
	Implements the GridLayoutModule::doCall().

bool	handleTrivial (const Graph &G, GridLayout &gridLayout, IPoint &boundingBox)
	Handles the special cases of graphs with less than 3 nodes.

Protected Attributes inherited from ogdf::GridLayoutModule
IPoint	m_gridBoundingBox
	The computed bounding box of the grid layout.

Detailed Description

Implementation of the Planar-Straight layout algorithm.

The class PlanarStraightLayout implements a straight-line drawing algorithm for planar graphs. It draws a planar graph on a grid of size at most (2n-4) * (n-2) without edge crossings.

The algorithm runs in several phases. In the first phase, the graph is augmented by adding edges to achieve a certain connectivity (e.g., biconnected or triconnected). Then, a shelling order of the the resulting graph is computed. Both phases are implemented by using module options, so you can replace them with different implementations. However, you have to make sure, that the connectivity achieved by the augmentation module is sufficient for the shelling order module (or the input graph already has the required connectivity).

The implementation used in PlanarStraightLayout is an improved version of an algorithm presented in:

Goos Kant: Drawing Planar Graphs Using the Canonical Ordering. Algorithmica 16(1), pp. 4-32, 1996.

Precondition

The input graph needs to be planar and simple (i.e., no self-loops and no multiple edges).

Optional parameters

Option	Type	Default	Description
sizeOptimization	bool	true	If this option is set to true, the algorithm tries to reduce the size of the resulting grid layout.
baseRatio	double	0.33	This option specifies the maximal number of nodes placed on the base line. The algorithm tries to place as many nodes as possible on the base line, but takes at most max(2, baseRatio * size of external face) many.

Module options

Instances of type PlanarDrawLayout provide the following module options:

Option	Type	Default	Description
augmenter	AugmentationModule	PlanarAugmentation	Augments the graph by adding edges to obtain a planar graph with a certain connectivity (e.g., biconnected or triconnected).
embedder	EmbedderModule	SimpleEmbedder	Planar embedding algorithm applied after planar augmentation.
shellingOrder	ShellingOrderModule	BiconnectedShellingOrder	The algorithm to compute a shelling order. The connectivity assured by the planar augmentation module has to be sufficient for the shelling order module!

Running Time

The computation of the layout takes time O(n), where n is the number of nodes of the input graph.

Definition at line 113 of file PlanarStraightLayout.h.

Constructor & Destructor Documentation

◆ PlanarStraightLayout()

ogdf::PlanarStraightLayout::PlanarStraightLayout ( )

Constructs an instance of the Planar-Straight layout algorithm.

◆ ~PlanarStraightLayout()

ogdf::PlanarStraightLayout::~PlanarStraightLayout ( )

inline

Definition at line 118 of file PlanarStraightLayout.h.

Member Function Documentation

◆ baseRatio() [1/2]

double ogdf::PlanarStraightLayout::baseRatio ( ) const

inline

Returns the current setting of option baseRatio.

This option specifies the maximal number of nodes placed on the base line. The algorithm tries to place as many nodes as possible on the base line, but takes at most max(2, m_baseRatio * size of external face) many.

Definition at line 143 of file PlanarStraightLayout.h.

◆ baseRatio() [2/2]

void ogdf::PlanarStraightLayout::baseRatio ( double ratio )

inline

Sets the option baseRatio to ratio.

Definition at line 146 of file PlanarStraightLayout.h.

◆ computeCoordinates()

void ogdf::PlanarStraightLayout::computeCoordinates	(	const Graph &	G,
		ShellingOrder &	lmc,
		NodeArray< int > &	x,
		NodeArray< int > &	y
	)

private

◆ doCall()

virtual void ogdf::PlanarStraightLayout::doCall	(	const Graph &	G,
		adjEntry	adjExternal,
		GridLayout &	gridLayout,
		IPoint &	boundingBox,
		bool	fixEmbedding
	)

overrideprivatevirtual

Implements the algorithm call.

A derived algorithm must implement this method and return the computed grid layout in gridLayout.

Parameters

G	is the input graph.
adjExternal	is an adjacency entry on the external face, or 0 if no external face is specified.
gridLayout	is assigned the computed grid layout.
boundingBox	returns the bounding box of the grid layout. The lower left corner of the bounding box is always (0,0), thus this IPoint defines the upper right corner as well as the width and height of the grid layout.
fixEmbedding	determines if the input graph is embedded and that embedding has to be preserved (true), or if an embedding needs to be computed (false).

Implements ogdf::PlanarGridLayoutModule.

◆ setAugmenter()

void ogdf::PlanarStraightLayout::setAugmenter ( AugmentationModule * pAugmenter )

inline

Sets the augmentation module.

The augmentation module needs to make sure that the graph gets the connectivity required for calling the shelling order module.

Definition at line 159 of file PlanarStraightLayout.h.

◆ setEmbedder()

void ogdf::PlanarStraightLayout::setEmbedder ( EmbedderModule * pEmbedder )

inline

Sets the module option for the graph embedding algorithm.

Definition at line 165 of file PlanarStraightLayout.h.

◆ setShellingOrder()

void ogdf::PlanarStraightLayout::setShellingOrder ( ShellingOrderModule * pOrder )

inline

Sets the shelling order module.

Definition at line 162 of file PlanarStraightLayout.h.

◆ sizeOptimization() [1/2]

bool ogdf::PlanarStraightLayout::sizeOptimization ( ) const

inline

Returns the current setting of option sizeOptimization.

If this option is set to true, the algorithm tries to reduce the size of the resulting grid layout.

Definition at line 131 of file PlanarStraightLayout.h.

◆ sizeOptimization() [2/2]

void ogdf::PlanarStraightLayout::sizeOptimization ( bool opt )

inline

Sets the option sizeOptimization to opt.

Definition at line 134 of file PlanarStraightLayout.h.

Member Data Documentation

◆ m_augmenter

std::unique_ptr<AugmentationModule> ogdf::PlanarStraightLayout::m_augmenter

private

The augmentation module.

Definition at line 174 of file PlanarStraightLayout.h.

◆ m_baseRatio

double ogdf::PlanarStraightLayout::m_baseRatio

private

The option for specifying the base ratio.

Definition at line 171 of file PlanarStraightLayout.h.

◆ m_computeOrder

std::unique_ptr<ShellingOrderModule> ogdf::PlanarStraightLayout::m_computeOrder

private

The shelling order module.

Definition at line 175 of file PlanarStraightLayout.h.

◆ m_embedder

std::unique_ptr<EmbedderModule> ogdf::PlanarStraightLayout::m_embedder

private

The planar embedder module.

Definition at line 173 of file PlanarStraightLayout.h.

◆ m_sizeOptimization

bool ogdf::PlanarStraightLayout::m_sizeOptimization

private

The option for size optimization.

Definition at line 170 of file PlanarStraightLayout.h.

The documentation for this class was generated from the following file:

include/ogdf/planarlayout/PlanarStraightLayout.h

OpenGraph DrawingFramework

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Precondition

Optional parameters

Module options

Running Time

Constructor & Destructor Documentation

◆ PlanarStraightLayout()

◆ ~PlanarStraightLayout()

Member Function Documentation

◆ baseRatio() [1/2]

◆ baseRatio() [2/2]

◆ computeCoordinates()

◆ doCall()

◆ setAugmenter()

◆ setEmbedder()

◆ setShellingOrder()

◆ sizeOptimization() [1/2]

◆ sizeOptimization() [2/2]

Member Data Documentation

◆ m_augmenter

◆ m_baseRatio

◆ m_computeOrder

◆ m_embedder

◆ m_sizeOptimization

Open
Graph Drawing
Framework