cvr::chainCode Class Reference
[Shape Analysis]

Elements of a Chaincode. More...

#include <cvrChainCode.h>

List of all members.

Public Types
enum	direction {   UNKNOWN = -2, NOMOVE = -1, E = 0, NE,   N, NW, W, SW,   S, SE }
Public Member Functions
	chainCode (const direction &v=NOMOVE)
	chainCode (const int v)
	chainCode (const chainCode &other)
	chainCode (const int x, const int y)
	chainCode (const ipoint &here, const ipoint &next)
direction	getDirection () const
bool	isDirection () const
ipoint	getNext (const ipoint &here) const
ipoint	getPrevious (const ipoint &here) const
int	deltaX () const
int	deltaY () const
ipoint	delta () const
chainCode &	operator= (const direction &other)
chainCode &	copy (const direction &other)
chainCode &	copy (const chainCode &other)
chainCode &	operator= (const chainCode &other)
bool	compare (const chainCode &other)
bool	operator== (const chainCode &other)
bool	compare (const direction &other)
bool	operator== (const direction &other)
chainCode &	subtract (const chainCode &first, const chainCode &second)
chainCode	operator- (const chainCode &other) const
chainCode &	subtract (const chainCode &other)
chainCode &	operator-= (const chainCode &other)
chainCode &	add (const chainCode &first, const chainCode &second)
chainCode	operator+ (const chainCode &other) const
chainCode &	add (const chainCode &other)
chainCode &	operator+= (const chainCode &other)
chainCode &	divide (const int other)
chainCode	operator/ (const int other)
ubyte	getCanzlerCode (const chainCode &nextChainCode) const
Static Public Attributes
Canzler Codes
Given two chain codes for a sequence of three adjacent pixels, the Canzler-Codes give you information about which borders of the middle pixel belong to the boundary. With the getCanzlerCode() you can obtain the corresponding coding for the pixel pointed by this chain code, if the next chain code is the one given. They are somehow similar to the so called "chain crack codes", but instead of specifying a direction of the boundary, they code which "crack codes" belong to the middle pixel between two chain codes. There are 16 Canzler-Codes, that can be obtained by the combination of the four values Top, Right, Bottom and Left, which specify that the border runs on the top, right, bottom and/or left edge of the pixel respectively.
static const ubyte	Nothing
static const ubyte	Top
static const ubyte	Right
static const ubyte	Bottom
static const ubyte	Left
Protected Member Functions
void	fromDeltas (const int x, const int y)
Protected Attributes
direction	value

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Detailed Description

Elements of a Chaincode.

The used directions follows the next diagram:

 NW   N   NE
    \ | /
 W -  x - E
    / | \
 SW   S   SE

The "int" value resulting from casting these chain codes is proportional to the angle with a proportionality constant of 45°, i.e. if 'c' is a chainCode object, then the equivalent direction in degrees is 45*int(c.getDirection()).

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Member Enumeration Documentation

enum cvr::chainCode::direction

Directions used in chain codes The used directions follows the next diagram:.

 NW   N   NE
    \ | /
 W -  x - E
    / | \
 SW   S   SE

The "int" value resulting from casting these chain codes is proportional to the angle with a proportionality constant of 45°, i.e. if 'c' is a chainCode object, then the equivalent direction in degrees is 45*int(c.getDirection()).

Enumerator:

UNKNOWN	Unknown.
NOMOVE	No Move.
E	East (or Right).
NE	North-East (or Right-Up).
N	North (or Up).
NW	North-West (or North-West).
W	West (or West).
SW	South-West (or Left-Down).
S	South (or Down).
SE	South-East (or Right-Down).

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Constructor & Destructor Documentation

cvr::chainCode::chainCode

(

const direction &

v = NOMOVE

)

[inline]

Left has value 8 (the fourth bit).

default constructor

cvr::chainCode::chainCode

(

const int

v

)

[inline]

constructor to cast an integer

cvr::chainCode::chainCode

(

const chainCode &

other

)

[inline]

copy constructor

cvr::chainCode::chainCode	(	const int	x,
		const int	y
	)			[inline]

Constrcutor.

This constructor creates a chainCode object using the sign of the parameters to calculate the direction. Image-coordinates are used, i.e. a positive "y" implies a change towards "south", and a positive x implies a change towards "east".

References fromDeltas().

cvr::chainCode::chainCode	(	const ipoint &	here,
		const ipoint &	next
	)			[inline]

Constructor.This constructor creates a chainCode object using two points.

References fromDeltas(), cvr::point< T >::subtract(), cvr::point< T >::x, and cvr::point< T >::y.

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Member Function Documentation

chainCode& cvr::chainCode::add

(

const chainCode &

other

)

[inline]

add the angles of the other chain code to this chainCode and leave the result in this instance.

Returns a reference to the instance

chainCode& cvr::chainCode::add	(	const chainCode &	first,
		const chainCode &	second
	)			[inline]

add the angles of the first and second chain codes

Referenced by operator+().

bool cvr::chainCode::compare

(

const direction &

other

)

[inline]

compare with another object

bool cvr::chainCode::compare

(

const chainCode &

other

)

[inline]

compare with another object

Referenced by operator==().

chainCode& cvr::chainCode::copy

(

const chainCode &

other

)

[inline]

become other object

chainCode& cvr::chainCode::copy

(

const direction &

other

)

[inline]

become other object

Referenced by operator=().

ipoint cvr::chainCode::delta

(

)

const [inline]

returns point with changes in both direction, x and y.

int cvr::chainCode::deltaX

(

)

const [inline]

returns change in x.

For example, if the value is NW, deltaX() returns -1.

int cvr::chainCode::deltaY

(

)

const [inline]

returns change in y.

For example, if the value is NW, deltaY() returns -1.

chainCode& cvr::chainCode::divide

(

const int

other

)

[inline]

divide chain code equivalent angle with an integer.

The result will be left in this instance and a reference to it will be returned

References value.

Referenced by operator/().

void cvr::chainCode::fromDeltas	(	const int	x,
		const int	y
	)			[inline, protected]

compute chain code from x and y deltas

Referenced by chainCode().

ubyte cvr::chainCode::getCanzlerCode

(

const chainCode &

nextChainCode

)

const [inline]

return the Canzler Code for the pixel pointed by this chainCode if the second chainCode is the one given as parameter.

The result a the bitwise OR of some of the codes Top, Bottom, Left and Right.

Parameters:

nextChainCode

the next chain code of this one in the chain code sequence.

Returns:

the canzler bit-coding for the edges of the pixel pointed by this chainCode which are part of the boundary. The values returned are bit or of the constants Left, Top, Right and Bottom.

direction cvr::chainCode::getDirection

(

)

const [inline]

returns direction of this chain element

ipoint cvr::chainCode::getNext

(

const ipoint &

here

)

const [inline]

returns next point with start point "here" and using this chainCode.

ipoint cvr::chainCode::getPrevious

(

const ipoint &

here

)

const [inline]

returns previous point with start point "here" and using this chainCode.

bool cvr::chainCode::isDirection

(

)

const [inline]

Possible Direction.returns true if this object contains one of the eight posible directions, and false otherwise.

chainCode cvr::chainCode::operator+

(

const chainCode &

other

)

const [inline]

add the angles of this and the other chain code

References add().

chainCode& cvr::chainCode::operator+=

(

const chainCode &

other

)

[inline]

add another chain code

chainCode cvr::chainCode::operator-

(

const chainCode &

other

)

const [inline]

subtract the angle equivalent of the other chainCode from *this

References subtract().

chainCode& cvr::chainCode::operator-=

(

const chainCode &

other

)

[inline]

subtract another chain code

References subtract().

chainCode cvr::chainCode::operator/

(

const int

other

)

[inline]

divide chain code angle with integer.

References divide().

chainCode& cvr::chainCode::operator=

(

const chainCode &

other

)

[inline]

become other object

References copy().

chainCode& cvr::chainCode::operator=

(

const direction &

other

)

[inline]

become other object

References copy().

bool cvr::chainCode::operator==

(

const direction &

other

)

[inline]

compare with another object

References compare().

bool cvr::chainCode::operator==

(

const chainCode &

other

)

[inline]

compare with another object

References compare().

chainCode& cvr::chainCode::subtract

(

const chainCode &

other

)

[inline]

subtract the angle equivalent of the other chain code from this one.

The result will be left in this instance, and a reference to it will be returned.

chainCode& cvr::chainCode::subtract	(	const chainCode &	first,
		const chainCode &	second
	)			[inline]

subtract the angles of the first and second chain code elements and leave the result here!

Referenced by operator-(), and operator-=().

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Member Data Documentation

const ubyte cvr::chainCode::Bottom [static]

Right has value 2 (the second bit).

const ubyte cvr::chainCode::Left [static]

Bottom has value 4 (the third bit).

const ubyte cvr::chainCode::Nothing [static]

Nothing has the value 0.

const ubyte cvr::chainCode::Right [static]

Top has value 1 (the first bit).

const ubyte cvr::chainCode::Top [static]

Nothing has the value 0.

direction cvr::chainCode::value [protected]

Attribute containing the chain code.

Referenced by divide().

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

• cvrChainCode.h