cv::LineIterator Class Reference

Line iterator. More...

#include <opencv2/imgproc.hpp>

Public Member Functions
	LineIterator (const Mat &img, Point pt1, Point pt2, int connectivity=8, bool leftToRight=false)
	initializes the iterator More...
uchar *	operator* ()
	returns pointer to the current pixel More...
LineIterator &	operator++ ()
	prefix increment operator (++it). shifts iterator to the next pixel More...
LineIterator	operator++ (int)
	postfix increment operator (it++). shifts iterator to the next pixel 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

Line iterator.

The class is used to iterate over all the pixels on the raster line segment connecting two specified points.

The class LineIterator is used to get each pixel of a raster line. It can be treated as 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 the iterator

creates iterators for the line connecting pt1 and pt2 the line will be clipped on the image boundaries the line is 8-connected or 4-connected If leftToRight=true, then the iteration is always done from the left-most point to the right most, not to depend on the ordering of pt1 and pt2 parameters

Member Function Documentation

operator*()

uchar* cv::LineIterator::operator*

(

)

returns pointer to the current pixel

operator++() [1/2]

LineIterator& cv::LineIterator::operator++

(

)

prefix increment operator (++it). shifts iterator to the next pixel

operator++() [2/2]

LineIterator cv::LineIterator::operator++

(

int

)

postfix increment operator (it++). shifts iterator to the next pixel

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