NeighborCode Class Reference

Encapsulation of direction management for the 8-neighborhood. More...

#include <vigra/pixelneighborhood.hxx>

Inheritance diagram for NeighborCode:

Public Types
enum	Direction {   Error = -1, East = 0, NorthEast, North,   NorthWest, West, SouthWest, South,   SouthEast, DirectionCount, CausalFirst = NorthEast, CausalLast = West,   AntiCausalFirst = SouthWest, AntiCausalLast = East }

Static Public Member Functions
static Diff2D const &	bottom ()
static Diff2D const &	bottomLeft ()
static Diff2D const &	bottomRight ()
static Direction	code (FourNeighborhood::Direction d)
static Direction	code (Diff2D const &diff)
static Diff2D const &	diff (Direction code)
static Diff2D const &	diff (int code)
static int	dX (Direction code)
static int	dX (int code)
static int	dY (Direction code)
static int	dY (int code)
static Diff2D const &	east ()
static bool	isDiagonal (Direction code)
static Diff2D const &	left ()
static unsigned int	nearBorderDirectionCount (AtImageBorder b)
static Direction	nearBorderDirections (AtImageBorder b, int index)
static Diff2D const &	north ()
static Diff2D const &	northEast ()
static Diff2D const &	northWest ()
static Diff2D const &	relativeDiff (Direction fromCode, Direction toCode)
static Diff2D const &	relativeDiff (int fromCode, int toCode)
static Diff2D const &	right ()
static Diff2D const &	south ()
static Diff2D const &	southEast ()
static Diff2D const &	southWest ()
static Diff2D const &	top ()
static Diff2D const &	topLeft ()
static Diff2D const &	topRight ()
static Diff2D const &	west ()

Detailed Description

Encapsulation of direction management for the 8-neighborhood.

This helper class allows the transformation between Freeman chain codes (East = 0, NorthEast = 1 etc.) and the corresponding Diff2D instances and back.

You can either use the chain codes by explicit qualification:

// the following three lines are equivalent
EightNeighborhood::NeighborCode::Direction d = EightNeighborhood::NeighborCode::East;
EightNeighborCode::Direction d               = EightNeighborCode::East;
EightNeighborhood::Direction d               = EightNeighborhood::East;

or you can fix 8-neighborhood by importing the entire namespace in your function:

using namespace EightNeighborhood;

Direction d = East;

If you want to pass 8-neighborhood codes as a template parameter, use the class EightNeighborhood::NeighborCode.

#include <vigra/pixelneighborhood.hxx>
Namespace: vigra::EightNeighborhood

Member Enumeration Documentation

enum Direction

Freeman direction codes for the 8-neighborhood. East = 0, North = 1 etc. DirectionCount may be used for portable loop termination conditions. CausalFirst and CausalLast are the first and last (inclusive) neighbors in the causal neighborhood, i.e. in the set of neighbors that have already been visited when the image is traversed in scan order. AntiCausalFirst and AntiCausalLast are the opposite.

Enumerator
Error
East
NorthEast
North
NorthWest
West
SouthWest
South
SouthEast
DirectionCount
CausalFirst
CausalLast
AntiCausalFirst
AntiCausalLast

Member Function Documentation

static unsigned int nearBorderDirectionCount ( AtImageBorder  b )

static

The number of valid neighbors if the current center is at the image border.

static Direction nearBorderDirections ( AtImageBorder  b, int  index  )

static

The valid direction codes when the center is at the image border. index must be in the range 0...nearBorderDirectionCount(b)-1.

static Diff2D const& diff ( Direction  code )

static

Transform direction code into corresponding Diff2D offset. (note: there is no bounds checking on the code you pass.)

static Diff2D const& diff ( int  code )

static

Equivalent to diff(static_cast<Direction>(code)). (note: there is no bounds checking on the code you pass.)

static Diff2D const& relativeDiff ( Direction  fromCode, Direction  toCode  )

static

Get the relative offset from one neighbor to the other. For example, relativeDiff(East, West) == Diff2D(-2,0). (note: there is no bounds checking on the code you pass.)

static Diff2D const& relativeDiff ( int  fromCode, int  toCode  )

static

Equivalent to relativeDiff(static_cast<Direction>(fromCode), static_cast<Direction>(toCode)). (note: there is no bounds checking on the code you pass.)

static int dX ( Direction  code )

static

X-component of diff()

static int dY ( Direction  code )

static

Y-component of diff()

static int dX ( int  code )

static

X-component of diff()

static int dY ( int  code )

static

Y-component of diff()

static Direction code ( FourNeighborhood::Direction  d )

static

Transform 4-neighborhood code into 8-neighborhood code.

static Direction code ( Diff2D const &  diff )

static

Transform Diff2D offset into corresponding direction code. The code Direction::Error will be returned if diff is not in the 8-neighborhood.

static bool isDiagonal ( Direction  code )

static

Check whether a code refers to a diagonal direction. Useful if you want to abstract the differences between 4- and 8-neighborhood.

static Diff2D const& right ( )

static

Offset to the right neighbor

static Diff2D const& topRight ( )

static

Offset to the topRight neighbor

static Diff2D const& top ( )

static

Offset to the top neighbor

static Diff2D const& topLeft ( )

static

Offset to the topLeft neighbor

static Diff2D const& left ( )

static

Offset to the left neighbor

static Diff2D const& bottomLeft ( )

static

Offset to the bottomLeft neighbor

static Diff2D const& bottom ( )

static

Offset to the bottom neighbor

static Diff2D const& bottomRight ( )

static

Offset to the bottomRight neighbor

static Diff2D const& east ( )

static

Offset to the east neighbor

static Diff2D const& northEast ( )

static

Offset to the northEast neighbor

static Diff2D const& north ( )

static

Offset to the north neighbor

static Diff2D const& northWest ( )

static

Offset to the northWest neighbor

static Diff2D const& west ( )

static

Offset to the west neighbor

static Diff2D const& southWest ( )

static

Offset to the southWest neighbor

static Diff2D const& south ( )

static

Offset to the south neighbor

static Diff2D const& southEast ( )

static

Offset to the southEast neighbor

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

• vigra/pixelneighborhood.hxx