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details NeighborCode Class Reference VIGRA

Encapsulation of direction management for 4-neighborhood. More...

#include "vigra/pixelneighborhood.hxx"


Public Types

enum  Direction {
  Error = -1, East = 0, North, West,
  South, DirectionCount, CausalFirst = North, CausalLast = West,
  AntiCausalFirst = South, AntiCausalLast = East
}

Static Public Methods

unsigned int nearBorderDirectionCount (AtImageBorder b)
Direction nearBorderDirections (AtImageBorder b, int index)
Diff2D const & diff (Direction code)
Diff2D const & diff (int code)
Diff2D const & relativeDiff (Direction fromCode, Direction toCode)
Diff2D const & relativeDiff (int fromCode, int toCode)
int dX (Direction code)
int dY (Direction code)
int dX (int code)
int dY (int code)
Direction code (Diff2D const &diff)
bool isDiagonal (Direction)
Diff2D const & right ()
Diff2D const & top ()
Diff2D const & left ()
Diff2D const & bottom ()
Diff2D const & east ()
Diff2D const & north ()
Diff2D const & west ()
Diff2D const & south ()


Detailed Description


Encapsulation of direction management for 4-neighborhood.

This helper class allows the transformation between Freeman chain codes (East = 0, North = 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
    FourNeighborhood::NeighborCode::Direction d = FourNeighborhood::NeighborCode::East;
    FourNeighborCode::Direction d = FourNeighborCode::East;
    FourNeighborhood::Direction d = FourNeighborhood::East;

or you can fix 4-neighborhood by importing the entire namespace in your function:

    using namespace FourNeighborhood;

    Direction d = East;

If you want to pass 4-neighborhood codes as a template parameter, use the class FourNeighborhood::NeighborCode.

#include "vigra/pixelneighborhood.hxx"
Namespace: vigra::FourNeighborhood


Member Enumeration Documentation


enum Direction

 

Freeman direction codes for the 4-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.

Enumeration values:
Error   
East   
North   
West   
South   
DirectionCount   
CausalFirst   
CausalLast   
AntiCausalFirst   
AntiCausalLast   


Member Function Documentation


Diff2D const& bottom   [inline, static]

 

Offset to the bottom neighbor


Direction code Diff2D const &    diff [inline, static]

 

Transform Diff2D offset into corresponding direction code. The code Direction::Error will be returned if diff is not in the 4-neighborhood.


Diff2D const& diff int    code [inline, static]

 

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


Diff2D const& diff Direction    code [inline, static]

 

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


int dX int    code [inline, static]

 

X-component of diff()


int dX Direction    code [inline, static]

 

X-component of diff()


int dY int    code [inline, static]

 

Y-component of diff()


int dY Direction    code [inline, static]

 

Y-component of diff()


Diff2D const& east   [inline, static]

 

Offset to the east neighbor


bool isDiagonal Direction    [inline, static]

 

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


Diff2D const& left   [inline, static]

 

Offset to the left neighbor


unsigned int nearBorderDirectionCount AtImageBorder    b [inline, static]

 

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


Direction nearBorderDirections AtImageBorder    b,
int    index
[inline, static]

 

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


Diff2D const& north   [inline, static]

 

Offset to the north neighbor


Diff2D const& relativeDiff int    fromCode,
int    toCode
[inline, static]

 

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


Diff2D const& relativeDiff Direction    fromCode,
Direction    toCode
[inline, 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.)


Diff2D const& right   [inline, static]

 

Offset to the right neighbor


Diff2D const& south   [inline, static]

 

Offset to the south neighbor


Diff2D const& top   [inline, static]

 

Offset to the top neighbor


Diff2D const& west   [inline, static]

 

Offset to the west neighbor


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

© Ullrich Köthe (koethe@informatik.uni-hamburg.de)
Cognitive Systems Group, University of Hamburg, Germany

html generated using doxygen and Python
VIGRA 1.5.0 (7 Dec 2006)