cv::LineIterator Class Reference

Class for iterating over all pixels on a raster line segment. More...

#include <opencv2/imgproc.hpp>

Public Member Functions
	LineIterator (const Mat &img, Point pt1, Point pt2, int connectivity=8, bool leftToRight=false)
	Initializes iterator object for the given line and image. More...
uchar *	operator* ()
	Returns pointer to the current pixel. More...
LineIterator &	operator++ ()
	Moves iterator to the next pixel on the line. More...
LineIterator	operator++ (int)
	Moves iterator to the next pixel on the line. More...
Point	pos () const
	Returns coordinates of the current pixel. More...

Public Attributes
int	count
int	elemSize
int	err
int	minusDelta
int	minusStep
int	plusDelta
int	plusStep
uchar *	ptr
const uchar *	ptr0
int	step

Detailed Description

Class for iterating over all pixels on a raster line segment.

The class LineIterator is used to get each pixel of a raster line connecting two specified points. It can be treated as a versatile implementation of the Bresenham algorithm where you can stop at each pixel and do some extra processing, for example, grab pixel values along the line or draw a line with an effect (for example, with XOR operation).

The number of pixels along the line is stored in LineIterator::count. The method LineIterator::pos returns the current position in the image:

// grabs pixels along the line (pt1, pt2)
// from 8-bit 3-channel image to the buffer
LineIterator it(img, pt1, pt2, 8);
LineIterator it2 = it;
vector<Vec3b> buf(it.count);

for(int i = 0; i < it.count; i++, ++it)
    buf[i] = *(const Vec3b*)*it;

// alternative way of iterating through the line
for(int i = 0; i < it2.count; i++, ++it2)
{
    Vec3b val = img.at<Vec3b>(it2.pos());
    CV_Assert(buf[i] == val);
}

Constructor & Destructor Documentation

LineIterator()

cv::LineIterator::LineIterator	(	const Mat &	img,
		Point	pt1,
		Point	pt2,
		int	connectivity = 8,
		bool	leftToRight = false
	)

Initializes iterator object for the given line and image.

The returned iterator can be used to traverse all pixels on a line that connects the given two points. The line will be clipped on the image boundaries.

Parameters

img	Underlying image.
pt1	First endpoint of the line.
pt2	The other endpoint of the line.
connectivity	Pixel connectivity of the iterator. Valid values are 4 (iterator can move up, down, left and right) and 8 (iterator can also move diagonally).
leftToRight	If true, the line is traversed from the leftmost endpoint to the rightmost endpoint. Otherwise, the line is traversed from pt1 to pt2.

Member Function Documentation

operator*()

uchar* cv::LineIterator::operator*

(

)

Returns pointer to the current pixel.

operator++() [1/2]

LineIterator& cv::LineIterator::operator++

(

)

Moves iterator to the next pixel on the line.

This is the prefix version (++it).

operator++() [2/2]

LineIterator cv::LineIterator::operator++

(

int

)

Moves iterator to the next pixel on the line.

This is the postfix version (it++).

pos()

Point cv::LineIterator::pos

(

)

const

Returns coordinates of the current pixel.

Member Data Documentation

count

int cv::LineIterator::count

elemSize

int cv::LineIterator::elemSize

err

int cv::LineIterator::err

minusDelta

int cv::LineIterator::minusDelta

minusStep

int cv::LineIterator::minusStep

plusDelta

int cv::LineIterator::plusDelta

plusStep

int cv::LineIterator::plusStep

ptr

uchar* cv::LineIterator::ptr

ptr0

const uchar* cv::LineIterator::ptr0

step

int cv::LineIterator::step

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

• opencv2/imgproc.hpp