vigra - NeighborCode Class Reference

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| 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

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

- vigra/pixelneighborhood.hxx

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python vigra 1.11.1 (Fri May 19 2017)